ISSN:0003-2654    

DOI:10.1039/AN99520FX005

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

ANALAO 120(2) 231 -582, 17N-28N (1 995) FEBRUARY 1995I~ '""An a I y stIH I1The analytical journal of The Royal Society of ChemistryCONTENTSGUEST EDITORIALPAPERS ON 'CLEAN'ANALYTICAL METHODS17N Towards Environmentally Conscientious Analytical Chemistry Through Miniaturization, Containment andReagent Replacement-Miguel de la Guardia, Jaromir Ruzicka231 In-line, Titanium Dioxide-catalysed, Ultraviolet Mineralization of Toxic Aromatic Compounds in the WasteStream from a Flow Injection-based Resorcinol Analyser-Miguel de la Guardia, Karim D. Khalaf, BerweenA. Hasan, Angel Morales-Rubio, Vicente Carbonell237 Photocatalytic Treatment of Laboratory Wastes Containing Aromatic Amines-Edmondo PramauroAlessandra Bianco Prevot, Vincenzo Augugliaro, Leonard0 Palmisano243 Seasonal and Areal Variations of Polycyclic Aromatic Hydrocarbon Concentrations in Street DustDetermined by Supercritical Fluid Extraction and Gas Chromatography-Mass Spectrometry-Yu Yang,Wolfram Baumann249 Costs, Laboratory Safety, Productivity and Faster Research Octane Number and Motor Octane NumberDeterminations in Industrial Chemistry Laboratories-J.M. Andrade, S. Muniategui, P. Lopez, D. Prada255 Spectrophotometric Determination of Copper(ii), Nickel(ii), and Cobalt(ii) as Complexes with SodiumDiethyldithiocarbamate in the Anionic Micellar Media of Dodecylsulfate Salts-M. P. San Andres, M. LMarina, S. Vera261 Quality Concepts and Practices Applied to Sampling. An Exploratory Study-Michael Thompson, MichaelH. Ramsey271 A Horwitz-like Function Describes Precision in a Proficiency Test-Michael Thompson, Philip J.Lowthian273 Orthogonal Array Design as a Chemornetric Method for the Optimization of Analytical Procedures. Part 3.Five-level Design and its Application in a Polarographic Reaction System for Selenium Determination-WeiGuang Lan, Ming Keong Wong, Kok Kay Chee, Yoke Min SinOrthogonal Array Design as a Chemometric Method for the Optimization of Analytical Procedures. Part 4.Mixed-level Design and its Application to the High-performance Liquid Chromatographic Determination ofPolycyclic Aromatic Hydrocarbons-Wei Guang Lan, Kok Kay Chee, Ming Keong Wong, Hian Kee Lee,Yoke Min Sin289 Chemornetric Evaluation of the Solvent Properties of Liquid Organic Salts-Salwa K.Poole, Colin F. Poole295 Development of a Novel Methodology in the Determination of Magnesium from Chlorophyll a by AtomicAbsorption Spectrometry Using Chemornetric Experimental Design-Pedro W. Araujo, KeyhandokhtKavianpour, Richard G. Brereton299 H-Point Standard Additions Method for Analyte Determination in Ternary Mixtures-J. Verdu Andres, F.Bosch Reig, P. Campins Falco305 Simultaneous Determination of Several Amino Acids With Multivariate Calibration Methods by Using aContinuous-flow System-J. Saurina, S. Hernandez-Cassou31 3 Application of the Partial Least-squares Calibration Method to the Simultaneous Kinetic Determination ofPropoxur, Carbaryl, Ethiofencarb and Formetanate-J. M. Garcia, A. I. Jimenez, J. J. Arias, Karim DKhalaf, Angel Morales-Rubio, Miguel de la Guardia31 9 Application of Near-infrared Reflectance Analysis to the Integrated Control of Antibiotic TabletProduction-Elena Dreassi, Giuseppe Cerarnelli, Luisa Savini, Piero Corti, Piero Luigi Perruccio, SilvanoLonardi325 Signal and Noise Analysis of Non-modulated Polarimeters Using Mueller Calculus Simulations-Uma Kale,Edward Voigtman331 Determination of Levamisole in Animal Tissues Using Liquid Chromatography-Thermospray MassSpectrometry-A. Cannavan, W.J. Blanchflower, D. G. Kennedy281Typeset and printed by Black Bear Press Limited,Cambridge, EnglandContinued on inside back cover33534134735135536 136737337738 138539 139540340741 341 942343 143744344745345746346747 1477Simultaneous Measurement of Lithium and Boron Isotopes as Lithium Tetraborate Ion by ThermalIonization Mass Spectrometry-Sarata K.Sahoo, Akimasa MasudaInvestigations Into the use of Inductively Coupled Plasma Mass Spectrometry for the Determination of Goldin Plant Materials-Cari A. Williams, Fadi R. Abou-Shakra, Neil I. WardQuantitative Analysis of Impurities in c-Caprolactam by Raman Spectroscopy-Christos G. Kontoyannis,Nicolaos Ch. Bouropoulos, Petros G. KoutsoukosQualitative and Semiquantitative Analysis of Annatto and its Content in Food Additives by PhotoacousticSpectrometry-Ulrich Haas, Carlos A. VinhaExtraction of Surfactants From Aqueous Media by Supercritical Fluid Extraction-M. Kane, J. R. Dean, S. M.Hitchen, C. J. Dowle, R.L. TranterSpeciation of Selenium and Arsenic Compounds in Natural Waters by Capillary Zone Electrophoresis AfterOn-column Preconcentration With Field-amplified Injection-Ke Li, Sam F. Y. LiTime-resolved Luminescence Detection of Europium(1ii) Chelates in Capillary Electrophoresis-MarttiLatva, Tim0 Ala-Kleme, Heidi Bjennes, Jouko Kankare, Keijo HaapakkaDetermination of Baclofen in Human Plasma and Urine by High-performance liquid chromatography withFluorescence Detection-Sedat Tosunoglu. Lale ErsoyReal-time Analysis of Multicomponent Chromatograms: Application to High-performance LiquidChromatography-Atsushi Yamamoto, Akinobu Matsunaga, Mikiya Ohto, Eiichi Mizukami, KazuichiHayakawa, Motoichi MiyazakiEnantiomeric Separation and Spectrofluorometric Detection of the Racemic Drugs,(f)-l-(2,6-Dimethylphenoxy)-2-propamine (Mexiletine) and (3RS)-4-Amino-3-hydroxybutanoic Acid(GABOB), Derivatized With 4-Fluoro-7-nitro-2,I ,3-benzoxadiazole on a Phenylcarbamylated CyclodextrinBonded Stationary Phase-Takeshi Fukushima, Masaru Kato, Tomofumi Santa, Kazuhiro lmaiDevelopment of Optically Active Fluorescent Edman-type Reagents-Toshimasa Toyo'oka, Yi-Ming LIULiquid-Liquid Extraction and Separation of Lanthanum(i1i) from Titanium@), Zirconium(iv), Hafnium(iv),Thorium(1v) and Uranium(vi)-N.G. Bhilare, V. M. ShindeDetermination of Free Selenomethionine in Nutritional Supplements by High-performance LiquidChromatography Coupled with Thermochemical Hydride Generation Atomic Absorption Spectrometry-G.Matni, R.Azani, M. R. Van Calsteren, M. C. Bissonnette, J . 3 . BlaisSalicylic Acid Functionalized Polystyrene Sorbent Amberlite XAD-2. Synthesis and Applications as aPreconcentrator in the Determination of Zinc(ii) and Lead(ii) by Using Atomic AbsorptionSpectrometry-Reena Saxena, Ajai K. Singh, Devendra P. S. RathoreAtomic Absorption Spectrometric Determination of Platinum and Rhodium in Cobalt OxideCatalyst-Barbara RozanskaDetermination of Trace Metals in Tea Using Both Microwave Digestion at Atmospheric Pressure andInductively Coupled Plasma Atomic Emission Spectrometry-Kathryn Lamble, Steve J. HillComparison of a Combined Helium-Argon Plasma With Pure Helium Plasmas for Gas ChromatographyWith Atomic Emission Detection-Antonio L. Pires Vaiente, Peter C.UdenNew Spectrofluorimetric Reagent, 2,3-Diamino-l,4-dibromonaphthalene, for the Determination of Seleniumin Biological Materials-Karin Johansson, Orjan Andersson, Ake OlinPyoverdin-doped Sol-Gel Glass for the Spectrofluorimetric Determination of lron(iii)-J. M. Barrero, C.Camara, M. C. Perez-Conde, C. San Jose, L. FernandezSolvent Extraction of Acenaphthene from Dodecane into Aqueous p-Cyclodextrin Medium and Applicationto Synchronous Spectrofluorimetric Determination in Kerosene-Masaki Tachi bana, Motohisa FurusawaDetermination of Three Aspirin Metabolites in Human Urine by Derivative SynchronousSpectrofluorimetry-Patricia Damiani, Maria Elida Ribone, Gabriela IbaAez, Alejandro C. OlivieriUpgrading a Rapid-scanning Spectrometer With Microcomputerized Data Acquisition and Treatment toMeasure Spectrokinetic Parameters of Photochromic Compounds-Jean-Jacques Meyer, Patrick Levoir,Roger DubestOptical Fibre Fluorosensor for Cadmium With Diethylaminoethyl-Sephadex as a Substrate-Jianzhong Lu,Zhujun ZhangOptical Oxygen Sensing Materials Based on the Room-temperature Phosphorescence Intensity Quenchingof Immobilized Erythrosin B-Marta Elena Diaz-Garcia, Rosario Pereiro-Garcia, Nieves Velasco-GarciaChemiluminescence Determination of Tetracyclines Based on Their Reaction With Hydrogen PeroxideCatalysed by the Copper Ion-X.R. Zhang, W. R. G. Baeyens, A. Van den Borre, G. Van der Weken, A. C.Calokerinos, S. G. SchulmanSensitized Determination of Sulfite Using Flow Injection With Chemiluminescent Detection-David A.Paulls, Alan TownshendFlow-injection Chemiluminometric Determination of Citrate Based on a Photochemical Reaction-TomasPerez-Ruiz, Carmen Martinez-Lozano, Virginia Tomas, Otilia ValInvestigation Into the Detection of Chlorine Species by Rhodamine 6G Chemiluminescence WithElectrochemical Modification-Gordon P.Irons, Gillian M. GreenwayContinued on facing pageNEWS AND ViEWS485 Determination of Total Base Number of Used Lubricating Oils From Marine Engines by FotentiometricTitration-Maria Purificacion Hernandez Artiga, Juan Antonio Muiioz Leyva, Ramon Cozar Sievert489 Kinetic Model of pH-based Potentiometric Enzymic Sensors. Part 4. Enzyme Loading and LifetimeFactors-Robert Koncki, Stanistaw Giqb495 Determination of Lead Using a Poly(viny1 chloride)-based Crown Ether Membrane-Suresh K.Srivastava,Vinod K. Gupta, Suresh Jain499 Nitrite-sensitive Liquid Membrane Electrodes Based on Metalloporphyrin Derivatives-De Gao, Jun Gu,Ru-Qin Yu, Guo-Dong Zheng503 Incorporation of Dodecyibenzenesulfonic Acid in a Poly(viny1 chloride) Matrix Chloride Ion-selectiveMembrane Based on Tertiary Ammoniu~Satoshi Nomura505 Use of Solid-phase Extraction Cartridges With Diff erentiai-pulse Cathodic Stripping Voltammetry at aHanging Mercury Drop Electrode: Determination of Nedocromil Sodium and Pentamidine lsethionate inUrine-Maria Valnice B. Zanoni, Josino C. Moreira, Arnold G. Fogg51 1 Square-wave Voltammetric Determination of Copper(i1) With a Nafion-Dimethylgtyoxime Mercury-filmElectrode--Jyh-Myng Zen, Nai-Yuen Chi, Fu-Shien Hsu, Mu-Jye Chung51 7 Application of Crown Ether Coated Piezoelectric Crystal as a Detector for Ion Chromat~r~~y-Yih-So~gJane, Jeng-Shong Shih523 ‘One-pot’ Electrochemical Determination of Copper and Formaldehyde in Electroless Copper Plating6aths-G. Bryan Balazs, Robert S.Glass, Leslie J. Summers529 Quantitative Determination of Cadmium, Zinc Thioneins Using Differential-pulse Polarography-AmaiiaMuiioz, Adela Rosa Rodriguez533 Inclusion Complexes and Stability Studies of an Organophosphorous Insecticide With Cyclodextrins:Sp~trop~~tometric and Kinetic Determination of Stability Constant-Yannis L. Loukas, Ekaterini A. Vyza,Aspasia P. Valiraki539 Spectrophotometric Determination of Alkaline Phosphatase and a-Fetoprotein in Human Serum With5,10,15,20-Tetrakis(4-phosphonooxyphenyl)porphin~Takanori Kawakami, Shukuro lgarashi543 Mechanism of Nitrite-cataiysed Oxidation of Chlorpromazine With Hydrogen Peroxide and/or DissolvedOxygen Used for the Determination of Nitrite-Bing Liang, Masaaki lwatsuki, Tsutomu Fukasawa549 Sp~troph~tometric Determination of Silver and Gold with 5-(2~4-Dihydr~xybenzylidene)rh~anine andCationic Surfactants-F.M. El-Zawawy, M. F. El-Shahat, A. A. Mohamed, M. T. M. Zaki555 Determination of Trace Amounts of Nickel by Chelating Ion Exchange and On-line Enrichment in FlowInjection Spectrophotometry-Rajesh Purohit, Surekha Devi561 Use of the Sequential injection Technique to Determine the Concentrations and Stoichiometries ofTrimeprazine and Perphenazine Complexed With Paf~adium(ii~ in Hydroc~toric Acid-Safah M. Sultan,Fakhr Eldin 0. Suliman, Bahruddin B. Saad565 Simultaneous Determination of Moly~enum and Tungsten Using a Flow Injection System and withoutPre-separation-Renmin Liu, Daojie Liu, Ailing Sun, Guihua Liu569 Simultaneous Determination of Copper and Zinc in the Hair of Children by pH Gradient Construction in aFlow injection System-Renmin Liu, Daojie Liu, Ailing Sun, Guihua Liu573 Spectrophotometric Determination of 1,4-Dihydroxyanthraquinone--Kan Jin-qing, Shi Yujun577 Screening of Calf Urine for 14Nortestosterone: Matrix Effect in Some Immonoassays-Maurizio PateofogoOriundi, Roberto Angeletti, E. Bastiani, Carlo ~ach~mann, Kristina E. Van~osthuyze, Carlos Van Peteghem581 CUMULATIVE AUTHOR INDEX19N Book Reviews21N Conference Oiary26N Courses27N Papers in Future IssuesCover picture: Can analytical science be environmentally conscientious? (see Guest Editorial). Backgroundphotograph kindly supplied by The Building Research Establishment, Garston, Watford

ISSN:0003-2654    

DOI:10.1039/AN99520BX007

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

Analyst, February 1995, Vol. 120 17N Guest Editorial ~ Towards Environmentally Conscientious Analytical Chemistry Through Miniaturization, Containment and Reagent Replacement The present state of the art in chemistry is immersed in an ecological period. After the development of the ancient chemical practices (the archaeological and alchemical periods) and from the foundation of chemistry as a science, chemistry progressed from chemology , chemurgy and iatrochemistry to a scientific discipline. Thus, the evolution of chemistry has been introverted; through the search for new chemical principles and through technological developments with applications to other areas, chemistry has focused on itself. However, further development of science and technology needs now also to pay attention to the interaction between man and the biosphere , and resulting environmental implica- tions.Therefore, analytical chemistry is moving from its former interest in inorganic analysis and organic analytical chemistry to bioanalysis and environmental studies. The traditional interest in the qualitative, quantitative and structural compo- sition of matter needs to be supplemented by yet another aspect, which will include the impact of its own activities on the environment. Although environmental analysis in itself is an important .step in the direction of ecological chemistry, the present focus on measurement of the influence of human activities does not address the negative aspect of current practices in analytical and research laboratories. This problem is likely to increase in the future, since the growing demand on analytical services increases the amount of chemical waste generated.Indeed, already requirements for the quality control of chemical and pharmaceutical production are expanding due to novel control activities, such as GMP (good manufacturing practices) and requirements of I S 0 9000. In addition, tighter regulations on chemical waste disposal create an unprecedented demand on additional assays to be carried out. As a result, large numbers of assays produce a considerable volume of highly diversified, often very toxic, chemical waste. As a majority of chemical assays are, and will remain, reagent-based, and since many reagents are toxic and/or carcinogenic, corrective action needs to be taken.It might be tempting to propose that alternative, more environmentally acceptable, reagentless chemistries ought to be developed. Yet, considering the past efforts of generations of chemists that were needed to develop present assays, it is not realistic to hope that such a replacement can be made within the immediate future. Also, the majority of EPA- and FDA-certified analytical methods use corrosive and toxic chemicals, with no currently available alternatives. Owing to the diversity of analytical methods, waste from the analytical laboratory is often complex, composed of relatively small individual volumes, but of a large variety of chemicals, the mixtures of which are expensive to dispose of. In contrast to large-scale industrial chemical processes (such as dry cleaning, paint formulation or the synthesis of bulk chemicals), the volume of waste is not substantially reduced when only a single method of processing is improved upon. Therefore , reagent replacement is not the most effective approach.A solution to this problem is to redesign existing reagent chemistries in such a way that the consumption of reagents, of sample material and waste production is minimized through miniaturization and that all solution handling tasks are fully contained and automated. This process will be driven not only by our environmental consciousness, but also by economy, since the costs of reagents and waste disposal are steadily increasing. The redesign of reagent-based assays will be carried out in many ways, through the use of (a) robotics, (6) miniaturized chromatographies, (c) flow techniques, such as flow injection and sequential injection, and (d) advances in sensor technol- ogy.Of these techniques, flow-based methodologies (e.g., chromatography, electrospray mass spectroscopy and stopped-flow injection) have the most significant potential, since in flow techniques, in contrast to batch methods, containment and washout is inherent and their miniaturization is not hindered by the difficulty of reproducibly dispensing microlitre volumes. Though the ideal goal should indeed be replacement of toxic chemicals by harmless ones, an initial goal is to reduce the use of toxic chemicals by a factor of ten. This realistic target will have a considerable positive impact, not only on the environ- ment and the economy of performing millions of assays daily, but also on the education of future generations of (analytical) chemists.As analytical chemistry progressively turns into what might be viewed as Chemical Instrumental Science, through redesign of its tools, it will have a considerable impact on how environmentally responsible the entirety of chemical research will become. Pollution prevention, as conceptualized in the US by the EPA, may take many routes. Although the main focus has been on the (petro)chemical industry and on manufacturing, where alternative chemistries are being sought, the approach must be different for the analytical and research laboratory. In the US Dr. Joe Breen from the EPA had the vision to propose that there is much that analytical chemists can do.In Europe, it was the Scientific Committee of the Flow Analysis Confer- ence in Toledo that made an award to the contribution focused on clean methods of analytical chemistry. There are, however, large differences between an ideal and real situation both in the USA and in Europe, where analytical and research laboratories remain a source of pollution. Because of this, it is important to turn the tide so that analytical chemists will contribute to the development of a ‘clean analytical chemistry’, which will avoid the unwanted effects of our activities. The term ‘conscientious analytical method’ could become a term to describing the efforts taken to reduce the undesirable side effects of the tools of the trade. Indeed, it is time to enhance the role of analytical chemistry to take a lead towards the preserving of our environment rather than to measure its deterioration. Such an approach will be yet another reason- able compromise between science and society, based on the co-operation of analytical chemists working on both sides of the Atlantic. Miguel de la Guardia and Jaromir Ruzicka

ISSN:0003-2654    

DOI:10.1039/AN995200017N

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

Analyst, February 1995, Vol. 120 19N Book Reviews Solid-state NMR I: Methods and II: Inorganic Matter * Edited by P. Diehli E. Fluck, H. Gunther, R. Kosfeld and J. Seelig. NMR Basic Principles and Progress. Volumes 30 and 31. Pp. x + 282 (Volume I); x + 216 (Volume 11). Springer-Verlag. 1994. Price DM248.00; sFr24.00; OS1934.00. ISBN 3-540-571 89-2 (Volume I); 3-540-571 90-6 (Volume II) Nuclear magnetic resonance (NMR) spectra of solids cannot be measured in the same way as those from liquids and solutions. This is because the presence in solids of anisotropic interactions which in liquids are exactly averaged by the rapid thermal motion of the molecules. Chemical applications of NMR rely greatly on the fact that the precise value of the radiofrequency absorbed by the various nuclei in an organic molecule depends on the chemical environments giving rise to distinct ‘chemically shifted’ lines.The parameters derived from the spectrum of a liquid (positions, widths, intensities and multiplicities of lines, relaxation rates and mechanisms) provide information on the structure, conformation and molecular motion. By contrast, conventional NMR of solids, instead of sharp spectral lines, gives broad humps that conceal most of the information of interest to a chemist. The development of magic-angle-spinning (MAS) NMR initiated a new era in the structural study of solids. The technique has greatly enhanced our knowledge of a wide range of materials used in the chemical, physical, biological and earth sciences and in the technology of glass and ceramics.However, it took nearly 20 years for MAS to become a routine tool for structural investigation. This is because of the difficulty in spinning the sample at the very high speeds required and insufficiently high magnetic fields. However, the introduction of Fourier-transform NMR, cross-polarization and superconducting magnets, during the 1960s and 1970s, greatly improved sensitivity. Many new techniques have appeared since Schaefer and Stejskal combined MAS and cross-polarization for the 13C NMR of organics. For example, double-rotation (DOR) NMR, in which the sample is rotated around two different axes simultaneously, can monitor the nature of phase transitions, while spin-echo double resonance (SEDOR) determines the relative spatial disposition of spins.Solid-state NMR is developing very rapidly and there is a constant need for up-to-date information about recent achievements. The general textbooks by Mehring and Fyfe were published more than 10 years ago, while the various monographs refer to specialized problems, and as such are of little interest to the general scientific audience. Volumes 30 and 31 of the series NMR Basic Principles and Progress refnedy the problem. Not that they are addressed to begin- ners, but they need to be read, with great profit, by all those who work in solid-state chemistry or physics and are familiar with basic NMR techniques. The 62-page opening chapter of NMR volume 30, entitled ‘Introduction to Solid-state NMR’, by Grimmer and Blumich is written in this spirit. The explanation of the fundamental techniques is very clear.Although the chapter necessarily covers mostly old ground, many modern examples are included. I note that the authors were able to dispense with the spherical tensor formalism, which chemists often find taxing. Laupr2tre’s ‘High-Resolution *3C NMR Investigations of Local Dynamics in Bulk Polymers at Temperatures Below and Above the Glass Transition Temperature’ is a useful mono- graph for everyone working with polymers. The chapter by Raftery and Chmelka on ‘Xenon NMR Spectroscopy’ is excellent. 129Xe NMR has recently found a number of uses in various fields (particularly heterogeneous catalysis), and the authors themselves have greatly contributed to this develop- ment. I am particularly impressed by their 129Xe 2D exchange spectrum (Fig. 19) and by the description of very exciting experiments that use optical pumping to probe the surfaces of solids.In the chapter ‘NMR as a Generalized Incoherent Scatter- ing Experiment’ Fleischer and Fujara draw on the analogy between stimulated echos in NMR and incoherent quasi- elastic neutron scattering. The chapter, which will have greater appeal to the physicist than to the chemist, is illustrated by some elegant experiments. The final contribu- tion, ‘NMR Imaging of Solids’, by Bliimler and Bliimich is an up-to-date exposition of a rapidly growing field with applica- tions mainly in chemical engineering. The various ideas described in this chapter will also be of interest to scientists working in medical imaging. ‘these two volumes are certainly very welcome and will be indispensable to most solid-state NlMR spectroscopists’.NMR volume 31 opens with the chapter by Engelhardt and Koller ‘2% NMR of Inorganic Solids’. Engelhardt has been pursuing fundamental 29Si and 27Al studies of silicates and aluminosilicates, particularly zeolites since 1980, and in 1987 published an excellent monograph on the subject (in collabor- ation with Michel). This chapter is, of course, more up to date than that book. Clays and amorphous silicates are also discussed, and a good account is given of Fyfe’s elegant two-dimensional 29Si studies of purely siliceous zeolites, which led to an unambiguous assignment of 29Si resonances to individual crystallographic sites for silicon in a number of materials. Pfeifer’s ‘NMR of Solid Surfaces’ is devoted to three topics: firstly, NMR studies of Brensted acid sites in zeolites, carried out mainly by the author’s group in Leipzig over the last 20 years are crucial to the understanding of the catalytic acidity of zeolites.No fewer than five different kinds of hydroxyls in zeolitic and AIP04 molecular sieves have been identified, and the NMR spectra correlated with infrared spectra; secondly, 27Al NMR studies of extra-framework aluminium are closely related to Lewis acidity; and thirdly, molecular transport measurements, using the pulsed field gradient method, provide a direct measure of diffusion coefficients of adsorbed species, superior to that given by volumetric measurements. Sebald’s chapter deals with ‘MAS and CP/MAS NMR of Less Common Spin-1/2 Nuclei’.89Y, 109Ag, 183W, 103Rh and 57Fe have low gyromagnetic ratios and are thus difficult to measure. However, they are important to a number of new materials, such as ceramics, high-temperature super- conductors, homo- and heteropolytungstates and hete- rogeneous catalysts. Nuclei with large chemical-shift anisotro- pies (119Sn, 199Hg, 207Pb, 195Pt and 205Tl) present spectro- scopic problems of their own, but their study provides useful structural information, especially for organometallic chem- istry. 113Cd is also an interesting nucleus. The author, who did much of the work in this field, correlates solid-state and solution spectra and summarizes the results with admirable clarity. Jager’s ‘Satellite Transition Spectroscopy of Quadrupolar Nuclei’ describes a useful method for deriving structural information on solids, particularly concerning quadrupolar parameters, from spinning sidebands which are often better resolved than the main resonance. A considerable gain in20N Analyst, February 1995, Vol.120 resolution is also found, especially for high-spin nuclei, when observing satellite transitions rather than the central transi- tion. Several applications to ‘difficult’ solids (such as glasses) are described. I wonder, however, whether the method really deserves the grand name of ‘spectroscopy’ (it is, after all, only one of many methods of NMR spectroscopy) or its own acronym (SATRAS). In the timely review ‘NMR-NQR Studies of High-Tempera- ture Superconductors’ Brinkmann and Mali summarize results in this field which involve mainly ‘NMR-unfriendly’ nuclei.The advanced methods described in this book will soon be more widely employed to resolve many hitherto inaccessible problems in solid-state chemistry and physics. The field is certain to flourish in the years to come. I do not know whether the publishers plan further volumes on solid-state NMR to cover subjects (such as double rotation, dynamic angle spinning, spin-echo double resonance, cross-polarization to and from quadrupole nuclei and rotational resonance, to name but a few) which have been left out of volumes 30 and 31. In any case, these two volumes are certainly very welcome and will be indispensable to most solid-state NMR spectro- scopists. Jacek Klinowski Department of Chemistry University of Cambridge, UK Efficiency in Research, Development and Production: The Statistical Design and Analysis of Chemical Experi- ments By Leslie Davies.Royal Society of Chemistry. Pp. xii + 180. 1993. Price f19.50. ISBN 0-85186-137-7. This book describes well some of the statistical techniques that have grown in the field of analytical chemistry. An easy to read book whose context covers the basics of error, accuracy and precision estimation, analysis of variance, experimental design and optimization procedures. The essentials of statis- tical analysis are dealt with in Chapter 2, which contains many worked examples and in-text exercises. Everything you would expect to find for the analytical chemist in terms of basic parametric testing can be found in this chapter.The main strength of this book and where it differs from other popular statistical texts is its in-depth approach to experimental design. Seven good chapters take the reader through the rationale of experimental design, factorial designs at two levels, fractional factorial designs at two levels, fractional factorial designs in sequence and factorial experiments at three levels. Again each chapter makes good use of worked examples and the fractional factorial approach is perhaps one of the best elucidations of the technique currently available to analytical chemists. In a more limited way, optimization forms the basis of chapters 4 , l l and 9 and although brief it was good to see a short chapter dedicated to Taguchi experimental design methodology. The book contains appendices of the necessary statistical tables and a valuable critique of current computer packages suitable for statistical data processing. Each chapter is augmented with a reference section and there is a very usable reference subject index at the rear of the book.To one who read the book cover to cover tne structure of the chapters seemed a little illogical with the Statistical Analysis chapter breaking up the Factorial Design chapters. In addition the optimization chapters have not been dealt with as a group. Nevertheless, to the reader who wants to access techniques and get going quickly with data analysis, there is a good contents list and one soon finds ones way around the chapters. A compact book of 180 pages, this book is bursting with information on how to statistically process data.Its great strength for me was its approach to experimental design which is a subject of growing importance but for which few good practical texts exist. Strongly recommended for its experimen- tal design, this book also offers a good readable source of basic statistical methods such as error and significance testing and deals suitably with optimization procedures. Reasonably priced and well produced by the RSC. S. J. Haswell School of Chemistry University of Hull, UK Computer-En hanced Analytical Spectroscopy Edited by Charles L. Wilkins. Modern Analytical Chem- istry. Volume 4. Pp. xviii + 308. Plenum. 1993. Price US$89.50. ISBN 0-306-44456-9. This is a collection of 12 papers presented at a symposium held in June 1992 on the application of chemometrics to analytical spectroscopy.They will probably be of more interest to people concerned with instrument and software design than to practising Analysts. Most of the usual chemometric methods make an appear- ance (principal components, neural networks, Kalman filters, maximum entropy and others). Each paper discusses its authors’ experience in applying such methods to a particular type of spectroscopy and a single or limited set of problems within that type. There are no general reviews covering all the possible methods for a problem or type of spectroscopy, nor all the applications of a chemometric method. Except for one paper on UVNIS spectroscopy most of the problems are either of structure determination or identifica- tion of ‘unknowns’ from a library.As is usual with chemome- trics most of the work is empirical, with concentration on the statistics and computing rather than on the underlying chemistry or the assignment of the spectral features. Excep- tions are a paper on computational chemistry which discusses the progress in ab initio calculation of vibrational spectra and the use of molecular mechanics to determine the conformation of adsorbed species in surface enhanced Raman spectroscopy and a paper on the prediction of fragmentation patterns in mass spectra. ‘focuses on statistics and computing rather than on the underlying chemistry’ A theme that appears in several papers is the need for instruments that are sufficiently robust for ‘field’ examination of samples, e.g., for identification of pollutants. Such instru- ments may have poorer resolution and calibration than laboratory instruments and the idea is to overcome this by chemometrics rather than by better engineering of the instruments. Analysts involved in these fields may be interes- ted to review this work and consider whether this approach is acceptable. Particular attention needs to be given to the libraries and training sets to ensure that the question ‘is this a controlled or forbidden substance?’ is not confused with ‘given that this is a forbidden substance, which forbidden substance is it?’. Andrew Coutts Rhone- Poulenc Rorer Essex, UK

ISSN:0003-2654    

DOI:10.1039/AN995200019N

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

Analyst, February 1995, Vol. 120 21N Conference Diary Date Conference Location Contact 6-10 9-10 13-16 24 28-31 28-30 28-30 29-30 April 3-6 10-13 23-25 26-28 May 3 7-10 PITTCON ’95, Pittsburgh Conference On Analytical Chemistry and Applied USA Spectroscopy Advances in Genetic Screening and Diagnosis of Human Diseases USA New Orleans, San Fransisco, Trace Elements, Free Radicals, Cytokines, Chromosomal Analysis and Tumour Markers in Clinical Medicine and Biochemistry Kuwait City, Kuwait The L.H. Sutcliffe Magnetic Resonance Symposium, covering ESR and NMR Scanning 95 Seventh Annual International Microscopy Meeting 3rd Symposium on Analytical Sciences Applications of Modern Mass Spectrometric Methods to Plant Science Research Atomic Spectrometry Updates 7th Instrumental Analysis Symposium Annual Chemical Congress (with Analytical Session) 6th International Symposium on Pharmaceutical and Biomedical Analysis 6th International Symposium on Chiral Discrimination New Techniques in Bioanalysis Handling of Environmental and Biological samples in Chromatography Guildford, UK California, USA Paris, France Swansea, UK Bristol, UK Madrid, Spain Edinburgh, UK St. Louis, USA St.Louis, USA Bradford, UK Lund, Sweden Pittsburgh Conference, Suite 332,300 Penn Centre Boulevard, Pittsburgh, PA 15235-9962, USA Ben Keddy, Cambridge Healthtech Institute, Bay Colony Corporate Center, 1000, Wirter Street, Suite 3700, Waltham, MA 02154, USA Tel: +1 617 487 7989. Fax: +1617 487 7937 Hussain Dashti, Department of Surgery, Faculty of Medicine, Kuwait University, P.O.Box 24923, Safat, Kuwait Fax: +965 531 8454 Dr. D. G. Gillies, Department of Chemistry, University of Surrey, Guildford, Surrey, UK GU2 5XH Mary K. Sullivan, Foundation for Advances in Medicine and Science, P.O. Box 832, Mahwah, NJ 07430 0832, USA Tel: +1 201 818 1010. Fax: +1 201 818 0086 The Scientific Committee-3rd SAS, 7 rue d’Argout, 75002 Paris, France Tel: +33 1 42 33 47 66 Dr. R. P. Newton, Biochemistry Group, School of Biological Sciences, University College, Swansea, Wales, UK SA2 8PP Tel: +44 (0)1792 295 377. Fax: +44 (0)1792 295 447 J. R. Dean, Department of Chemical and Life Sciences, University of Northumbria at Newcastle, Ellison Building, Newcastle upon Tyne, UK NE1 8ST Tel: +44 (0)191 227 3517. Fax: +44 (0)191227 3519 7a Jomadas de Analisis Instrumental (JAI) Expoanalitica & Biocienca, Arda Reina Ma Cristina, Palacio no. 1, 08004-Barcelona, Spain Tel: +34 3 423 3101.Fax: +34 3 423 6348 Dr. J. F. Gibson, The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Tel: +44 (0)171437 8656. Fax: +44 (0)171 734 1227 Shirley Schlessinger, 400, East Randolph Street, Suite 1015, Chicago, Illinois 60601, USA Tel: +1312 527 2011. Shirley Schlessinger, 400, East Randolph Street, Suite 1015, Chicago, Illinois 60601, USA Tel: +1 312 527 2011. A. J. Crooks, ‘Cartref, 35 Queensbury Road, Salisbury, Wiltshire, UK SP1 3PH Tel: +44 (0)1722 334974. Mrs. M. Frei-Hausler, Postfach 46, CH-4123 Allschwil 2, Switzerland Fax: +41 61 482 080522N Analyst, February 1995, Vol. 120 Date 7-1 1 7-1 1 9-12 14-18 16-18 21-26 21-26 21-26 22-24 28-216 June 5-8 11-14 13-16 July 2-6 2-7 9-13 Conference Location 86th AOCS Annual Meeting & Expo Texas , USA Seventeenth International Symposium on Virginia, Capillary Chromatography and USA Electrophoresis Metal Compounds in Environmental and Life Jiilich , &Analysis, Speciation and Specimen Banking Germany EMAS 95 on Modern Developments and Applications in Microbeam Analysis France Fourth International Conference on Progress in Analytical Chemistry in the Steel and Metals Industry St Malo, Luxembourg CLEO '95: Conference on Lasers and Electro- Baltimore, Optics USA QELS '95: Quantum Electronics and Laser Science Conference USA Baltimore , ASMS Conference on Mass Spectrometry Atlanta, USA Eighth International Symposium on Polymer Analysis and Characterization (ISPAC-8) USA Sanibel Island, 19th International Symposium on Column Liquid Chromatography Austria Innsbruck , 5th Symposium on our Environment and 1st Asia-Pacific Workshop on Pesticides Singapore Convention City, 1995 International Symposium, Exhibit and Workshops on Preparative Chromatography, USA Ion Exchange, and AdsorptiodDesorption Processes Washington DC, ESIS 95-New Infrared Spectroscopy and Microspectroscopy: FTIR and Raman France Lyon, VII International Congress of Toxicology Seattle, USA 12th International NMR Meeting Manchester , UK 3rd International Symposium on Applied Mass Barcelona, Spectrometry in Health Sciences and 3rd Spain European Tandem Mass Spectrometry Conference Contact AOCS EducatiodMeetings Department, P.0. Box 3489, Champaign, IL 61826-3489, USA Tel: +1 217 359 2344. Fax: +1 217 351 8091 Dr. Milton L. Lee, Department of Chemistry, Brigham Young University, Provo, UT 84602- 4672, USA Tel: +1 801 378 2135. Fax: +1 801 378 5474 H. W. Durbeck, Institute of Applied Physical Chemistry, Research Center Julich (KFA), P.O. Box 1913, D-5170 Jiilich, Germany EMAS Secretariat, RIKILT-DLO, P.O. Box 230, 6700 AE Wageningen, The Netherlands R. Jowitt, British Steel plc, Technical, Teesside Laboratories, P.O. Box 11, Grangetown, Middlesbrough, Cleveland, UK TS6 6UB Fax: +44 (0)1642 460321 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, Tel: +1202 223 9034. Fax: +1202 416 6100 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, Tel: +1202 223 9034.Fax: +1 202 416 6100 ASMS, 815 Don Gaspar, Santa Fe, NM 87501, USA Tel: +1 505 989 4517. ISPAC Registration, 815 Don Gaspar, Sante Fe, NM 87501 USA Tel: + 1 505 989 4735. Fax: + 1 505 989 1073 HPLC '95 Secretariat, Tyrol Congress , Marktgraben 2, A-6020 Innsbruck, Austria Tel: +43 512 575600. Fax: +43 512 575607 DC 20036-1023, USA DC 20036-1023, USA. The Secretariat, 5th Symposium on our Environment, c/o Department of Chemistry, National University of Singapore, Kent Ridge, Republic of Singapore 0511 Fax: +65 779 1691 Mrs. Janet Cunningham, PREP '95 Symposium/ Exhibits Manager, Barr Enterprises, 10120 Kelly Road, P.O. Box 279, Walkersville, MD 21793, USA Tel: +1 301 898 3772. Fax: +1 301 898 5596 G.Lachenal, Laboratoire des Materiaux Plastiques et Biomateriaux, UniversitC Claude Bernard Lyon 1,43 Boulevard du 11 Novembre, 69622 Villeurbanne Cedex, France Jada Hill, The Sterling Group, 9393 W, 110th St., Suite, Overland Park, KS 66210, USA Tel: + 1 913 345 2228. Fax: + 1 913 345 0893 Dr. J. E. Gibson, Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Professor Emilio Gelpi, Palau de Congressos, Departamento de Convencions, Avda, Reina Ma Christina, 08004 Barcelona, SpainAnalyst, February 1995, Vol. 120 23N Date Conference Location 9-14 13th Australian Symposium on Analytical Darwin, Chemistry/4th Environmental Chemistry Australia Conference 9-15 SAC 95 Hull, UK 10-13 Vth COMTOX Symposium on Toxicology and Vancouver, Clinical Chemistry of Metals Canada 30-518 XXIInd International Conference on Phenomena in Ionized Gases August 5-10 13-17 20-25 27-21 9 27-119 27-119 27-30 Hoboken, USA 1995 International Symposium on Soil and Plant Analysis The Netherlands Wageningen, ICFIA '95,7th International Conference on Seattle, Flow Injection Analysis and JAFIA, Japanese USA Association for Flow Injection Analysis 12th International Symposium on Plasma Chemistry USA Minneapolis, CSI XXIX: Colloquium Spectroscopicum Leipzig, Internationale Germany 46th Annual Meeting of the International Society of Electrochemistry (ISE46) China Xiamen, Third International Conference on Magnetic Resonance Microscopy Germany Wiirzburg, EUROTOX September 1-4 CSI XXIX, Post-symposium ICP-MS and 11th German ICP-MS Users Meeting 3-6 Third International Meeting on Recent Advances in Magnetic Resonance Application to Porous Media 6th European Conference on the Spectroscopy of Biological Molecules 3-8 Prague, Czech Republic Contact 13AC/4EC, Symposium Secretariat, Convention Catalyst Int., GPO Box 2541, Darwin NT 0801, Australia Tel: +61 89 811 875.Fax: +6189 411 639 Analytical Division, The Royal Society of Chemistry, Burlington House, Piccadilly, London, UK W1V OBN Tel: +44 (0)171437 8656. Fax: +44 (0)171 734 1227 F. William Sunderman, Jr., M.D., Departments of Laboratory Medicine and Pharmacology, University of Connecticut Medical School, P.O. Box 1292, Farmington, CT 06034-1292, USA Tel: +1203 679 2328. Fax: +1 203 679 2154 E. E. Kunhardt, Physics Department, Stevens Institute of Technology, Hoboken, NJ 07030 USA Tel: +1201216 5099.Fax: +1201216 5638 Soil and Plant Analysis Council,, Georgia University Station, P.O. Box 2007, Athens, GA Tel: + 1 706 546 0425. Fax: + 1 706 548 4891 Gary D. Christian, Department of Chemistry, BG-10, University of Washington, Seattle, WA 98195, USA Tel: t-1206 685 3478. Fax: +1206 543 5340. E-Mail: christia@chem.washington.edu L. Graven, 315 Pillsbury Drive, SE, University of Minnesota, Minneapolis, MN 55455-0139, USA Tel: +1 612 625 9023. Fax: +1 612 626 1623 GDCh-Geschiiftsstelle, Abt. Tagungen, Varrentrappestr. 4042, Postfach 90 04 40, D-6000 Frankfurt am Main 90, Germany Tel: +49 69 791 7358. Fax: +49 69 791 7475 Secretariat, XLVIth ISE Annual Meeting, P.O. Box 1995, Xiamen University, Xiamen 361005, China Tel: +86 592 208 5349.Fax: +86 592 208 8054 Dr. A. Haas, Physikalisches Institute, Universitat Wurzburg, Am Hubland, D-97074 Wiirzburg, Germany Czech Medical Association J. E. Purkyng, EUROTOX '95, P.O. Box 88, Sokolska 31,120 26 Prague 2, Czech Republic Tel: +42 2 24 915195. Fax: +42 2 24 216836 30612-2007, USA Wernigerode, Germany Professor Lieselotte Moenke, Department of Chemistry, Martin-Lu ther University, Halle- Wittenberg, Institute of Analytical and Environmental Chemistry, Weinbergweg 16, D-06120 Halle, Germany Louvain la Neuve, Professor J. M. Dereppe, Universite de Louvain, Belgium Place L. Pasteur 1, B-1348, Louvain la Neuve, Belgium Villeneuve Professor J. C. Merlin, ECSBM '95, LASIR, UST d' Ascq, Lille Bit. C5,59655 Villeneuve d'Ascq Cedex, France France24N Analyst, February 199.5, Vol.120 Date 5-8 10-14 12-15 17-21 24-28 25-28 Conference Location October RSC Autumn Medting. Analytical and Faraday Sheffield, Symposium: Ions in Solution UK Ion-Ex ’95, The Fourth International Conference and Industrial Exhibition on Ion Exchange Processes Wrexham, UK 5th I- ‘-rnational Symposium on Drug Analysis Leuven, Belgium 30th Annual Meeting of the Federation of Analytical Chemistry and Spectroscopy USA Societies 11th Asilomar Conference on Mass Spectrometry-Molecular Structure USA Determination: Activation, Mass Analysis and Detection 5th Symposium on ‘Kinetics in Analytical Chemistry’ (KAC ’95) Russia Philadelphia, Pacific Grove, Moscow, 1-5 9-13 15-20 24-27 21st World Congress of the International Society for Fat Research (ISF) The Hague, The Netherlands ECASIA ’95 Montreux, Switzerland 22nd Annual Conference of the Federation of Analytical Chemistry and Spectroscopy USA Societies Cincinnati, BCEIA ’95-The International Sixth Beijing Conference and Exhibition on Instrumental Analysis Beijing, China November 5-10 1st Mediterranean Basin Conference on Cordoba, Analytical Chemistry Spain 5-10 OPTCON’95 San Jose, USA 14-15 International Conference for Chemical Manchester , Information Users UK December 17-22 International Symposium on Environmental Hawaii, Biomonitoring and Specimen Banking USA 20-21 2nd LCMS Symposium Cambridge, UK Contact Dr.J. F. Gibson, The Royal Society of Chemistry, Burlington House, Piccadilly , London, UK W1V OBN Tel: +44 (0)171437 8656. Fax: +44 (0)171734 1227 Ion-Ex ’95 Conference Secretariat, Faculty of Science, The North East Wales Institute, Connah’s Quay, Deeside, Clwyd, UK CH5 4BR Fax: +44 (0)1244 814305 Professor J.Hoogmartens, Institute of Pharmaceutical Sciences, Van Evenstraat 4, B-3000 Leuven, Belgium Tel: +32 16 32 34 40. Fax: +32 16 32 34 48 FACSS, P.O. Box 278, Manhattan, KS 66502-0003, USA Tel: +1301846 4797 Professor R. Graham Cooks, Department of Chemistry, 1393 Brown Building, Purdue University, West Lafayette, IN 47907, USA Dr. I. F. Dolmanova, Analytical Chemistry Division, Chemical Department, Lomonosov Moscow State University, 119899 Moscow, Russia Tel: +7 095 939 3346. Fax: +7 095 939 2579 Mrs. J. Wills, ISF Secretariat, P.O. Box 3489, Champaign, IL 61826-3489, USA Tel: +1217 359 2344.Fax: +1217 351 8091 EPEL-ECASIA 95, Department des Materiaud LMCH, CH-1015 Lausanne, Switzerland Fax: +4121693 3946 Joseph A. Caruso, FACSS National Office, 198 Thomas Johnson Dr., Suite S-2, Frederick, MD 21702, USA Tel: +1301694 8122. Fax: +1301694 6860 General Service Office, The International Sixth BCEIA, Room 585, Chinese Academy of Science Room, San Li He, Xi Jiao, P.O. Box 2143, Beijing 100045, China Professor Alfredo Sanz-Medel, Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, C/Julian Claveria, no. 8 33006 Oviedo, Spain Tel: +34 85 103474. Fax: +34 85 103480 Meetings Department, Optical Society of America, 2010 Massachusetts Avenue, NW, Washington, Tel: + 1 202 223 9034. Fax: + 1 202 416 6100 Dr.M. P. Coward, Chemistry Department, UMIST, P.O. Box 88, Manchester, UK M60 1QD Tel: +44 (0)161200 4491. Fax: +44 (0)161228 1250 DC 20036-1023, USA K. S. Subraimanian, Environmental Health Directorate, Health Canada, Tunney’s Pasture, Ottawa, Ontario, Canada K1A OL2 Tel: +1613 957 1874. Fax: +1613 941 4545 Dr. J. Oxford, Glaxo Research and Development, Park Road, Ware, Hertfordshire, UK SG12 ODJAnalyst, February 1995, Vol. 120 25N Date Conference Location 1996 January 8-13 1996 Winter Conference on Plasma Florida, Spectrometry USA 21-25 VIth Latin American Congress on Caracas, Chromatography Venezuela February 6 9 Fourth International Symposium on Bruges , Hyphenated Techniques in Chromatography Belgium (HTC 4); Hyphenated Chromatographic Analysers March 17-21 31414 April 23-36 May 7-9 June 16-21 July 8-12 47th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy USA Atlanta, 7th International Symposium on Supercritical Indianapolis, Fluid Chromatography and Extraction USA Analytica Conference '96 Munich, Germany VIIth International Symposium on Monte-Carlo, Luminescence Spectrometry in Biomedical Monaco Analysis-Detection Techniques and Applications in Chromatograph and Capillary Electrophoresis HPLC ' 9 6 20th International Symposium on High Performance Liquid Chromatography USA San Francisco, XVI International Congress of Clinical Chemistry UK London, September 1-7 Euroanalysis IX Bologna, Italy 15-20 21st International Symposium on Stut tgart , Chromatography Germany 30-4111 31st Annual Meeting of the Federation of Kansas City, Analytical Chemistry and Spectroscopy USA Societies Contact R.Barnes, Department of Chemistry, Lederle GRC Tower, University of Massachusettes, P.O. Box 34510, Amherst, MA 01003-4510, USA Tel: +1 413 545 2294. Fax: +1 413 545 4490 Irene Romero, Interep SA, P.O. Box 76343, Caracas 1070-A, Venezuela Dr. R. Smits, Royal Flemish Chemical Society (KVCV), Working Party on Chromatography, BASF Antwerpen N.V., Central Laboratory, Haven 725, Scheldelaan 600, B-2040 Antwerp, Belgium Tel: +32 3 561 2831. Fax: +32 3 561 3250 The Pittsburgh Conference, 300 Penn Center Boulevard, Suite 332, Pittsburgh, PA 15235-5503 USA Tel: +1412 825 3220. Fax: +1412 825 3224 Janet Cunningham, Barr Enterprises, 10120 Kelly Road, P.O. Box 279, Walkersville, MD 21793 USA Tel: +1301898 3772. Fax: +1301898 5598 Congress Center, Messegelande, D-80325 Munchen, Germany Tel: +49 89 5107 159. Fax: +49 89 5107 180 Prof. Dr. Willy R. G. Baeyens, University of Ghent, Pharmaceutical Institute, Department of Pharmaceutical Analysis, Harelbekestraat 72, B-9000 Ghent, Belgium Tel: +32 9 221 8951. Fax: +32 9 221 4175 Mrs. Janet Cunningham, Barr Enterprises, P.O. Box 279, Walkersville, MD 21793, USA Tel: +1301898 3772. Fax: +1301898 5596 Mrs. Pat Nielsen, XVIth International Congress of Clinical Chemistry, P.O. Box 227, Buckingham, UK MK18 5PN Fax: +44 (0)1280 6487 Professor Luigia Sabbatini, Euroanalysis IX, Dipartimento di Chimica, Universitg di Bari, Via Orabona, 4, 70126 Bari, Italy Tel: +39 80 242020. Fax: +39 80 242026 GDCh-Geschiiftsstelle, Abt. Tagungen, Varrentrappestr. 40-42, Postfach 90 04 40, D-6000 Frankfurt am Main 90, Germany Tel: +49 69 791 7358. Fax: +49 69 791 7475 FACSS, P.O. Box 278, Manhattan, KS 66502-0003, USA Tel: +1 301 846 4797

ISSN:0003-2654    

DOI:10.1039/AN995200021N

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

26N Analyst, February 1995, Vol. 120 Courses Date Conference Location April 4-5 Workshop in Chemical Information Retrieval Manchester, UK 4-7 Short Course on Chiral Resolution Rome, Italy 5 Nuclear Waste Disposal Loughborough, UK May 10 Education and Training of Chromatographers London, UK 18 Meat Authenticity: Introduction to Immunoassay Test Kits 21 Techniques for Polymer Analysis and Characterization 22-25 Modern Practice of Gas Chromatography 30-1/6 Sixteenth Annual Introductory HPLC Short Course June 7-12 4th Annual Course on Practical Methods of Digestion for Trace Analysis 6-8 5th Annual Flow Injection Atomic Spectrometry Short Course 16-20 Capillary Electrophoresis, Routine Method for Campden, UK Sanibel Island, USA Pens> USA Pens) USA vania, vania, Am herst, USA Amherst, USA Montpellier, the Quality Control of Drugs: Practical Approach France 26-30 Radioisotope Techniques Short Course Loughborough, UK July 17-19 Techniques Workshop (Chemometrics) Hull, UK Contact Dr.M. P. Coward, Chemistry Department, UMIST, P.O. Box 88, Manchester, UK M60 1QD Tel: +44 (0)161200 4491. Fax: +44 (0)161228 1250 Dr. S. Faniti, CNR, Istituto di Cromatografia, C.P.10,100016, Monterotondo Scalo, Roma, Italy Fax: +39 6 906 25 849 Dr. P. Warwick, Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire, UK LEll 3TU Tel: +44 (0) 1509 222585 Dr. D. Simpson, Analysis for Industry, Factories 2/3, Bosworth House, High Street, Thorpe-le- Soken, Essex, UK C016 OEA Tel: +44 (0)1255 861714. Fax: +44 (0)1255 662111 Training Department, Campden Food and Drink Research Association, Chipping Campden, Gloucester, UK GL55 6LD Tel: +44 (0)1386 840319.Fax: +44 (0)1386 841306 Dr. Petr Munk, Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA Tel: +1512 471 4179. Fax: +1512 471 8696 Sally Stafford, Hewlett-Packard, Little Falls Site, 2850 Centerville Road, Wilmington, DE 19808- 1610, USA Tel: +1302 633 8444 Bill Champion, DuPont Merck Pharmaceutical Company, PRF Building, Chambers Works, Deepwater, NJ 08023, USA Tel: +1 609 540 4826 Nancy Teranto, Questron Corporation, 4044 Quakerbridge Road, Mercerville, NJ08619 USA Tel: + 1 609 587 6898. Fax: + 1 609 587 0513 J. Tyson, Department of Chemistry, LGRC Tower, University of Massachusetts, Box 34510, Amherst, MA 01003-4510 USA Tel: +1413 545 0195. Fax: +1413 545 4846 Professor H. Fabre, Laboratory of Analytical Chemistry, Faculty of Pharmacy, 15 Avenue Charles Flahault 34060 Montpellier, France Tel: +33 67 54 45 20. Fax: +33 67 52 89 15 Dr. P. Warwick, Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire, UK LEll 3TU Tel: +44 (0)1509 222585 Dr. M. J. Adams, School of Applied Sciences, University of Wolverhampton, Wulfruna Street, Wolverhampton, UK WV1 1SB Tel: +44 (0)1902 322141. Fax: +44 (0)1902 322680 Entries in the above listing are included at the discretion of the Editor and are free of charge. If you wish to publicize a forthcoming meeting please send full details to: The Analyst Editorial Office, Thomas Graham House, Science Park, Milton Road, Cambridge, UK CB4 4WF. Tel: +44 (0)223 420066. Fax: +44 (0)223 420247.

ISSN:0003-2654    

DOI:10.1039/AN995200026N

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

Analyst, February 1995, Vol. 120 27N Future Issues will lnclude- Near-infrared reflectance spectroscopy in the determination of the physical state of primary materials in pharmaceutical production-Piero Corti, EIena Dreassi, Giuseppe Ceramelli, Luisa Savini and Piero Luigi Perruccio Sorption of yttrium hydroxyquinolinates by polyurethane foam and its use in analysis-S. V. Beltyukova, Nine1 A. Nazarenko and Svetlana V. Tsygankova Laser-induced fluorescence in the graphite furnace as a sensitive technique for the assessment of traces in North Arctic atmospheric aerosol samples-Jonas Enger, Yvonne Malmsten, Peter Ljungberg and Ove Axner Generalized method for the simultaneous multicomponent determinations through a single catalyst kinetic run by using the rate spectrum-Zhi-Cheng Gu and Xian-De Wang Determination of oligomer distribution of alkylphenol poly- ethoxylates and fatty alcohol polyethocylates by positive ion atmospheric pressure chemical ionization-mass spectrometry -S.Pattanaargsorn, S. Sangvanich, P. Petsom and S. Roengsumran Studies on the voltammetric behaviour of puerarin and its application-Hu Jingho and Li Qilong Copper, zinc and aluminium from dietary sources in the femur, brain and kidney of guinea pigs and a study of some elements in in vivo intestinal digesta by size exclusion chromatography-inductively coupled plasma-mass spec- trometry-Helen M. Crews, Linda M. W. Owen, Robert C. Massey and Nicholas J. Bishop Determination of ytterbium using europium modifier and graphite furnace atomic absorption spectrometry-Zhang Jie and Sixuan Guo Neutron activation analysis of environmental objects-G. M.Kolesov Inductively coupled plasma-atomic emission spectrometry analysis of low levels of selenium in natural waters-Rob L. Adkins, Nick Walsh, Mike Edmunds and Janice M. Trafford Inductively coupled plasma-atomic emission spectroscopic determination of rare earth elements in granites and breisens using thin layer chromatography preconcentration-Natalia S. Safronova, Svetlana S. Matveeve, Yury I. Fabelinsky and Valentin A. Ryabukhin Neutron activation analysis of platinum, palladium, iridium and gold in reference materials: A comparison between two methods-Claudio A. Noguiera and Ana M. G. Figueiredo Cyanide detection using an amperometric biosensor of tyrosi- nase with catechol substrate-Xiaoya Hu and Zongahou Leng Estimation of sampling bias between different sampling protocols on contaminated land-M.H. Ramsey, Ariadni Argyraki and Michael Thompson Effects of acute exercise on urinary losses and serum concentrations of copper and zinc of moderately trained and untrained men consuming a controlled diet-Richard A. Anderson, Noella A. Bryden, Marilyn M. Polansky and Patricia Deuster Ion probe measurements of trace elements in NIST SRM-610 Glass Standards-Richard W. Hinton, G. Witt-Eickschen and B. Harte Flow injection of tetracyclines by electrocatalytic oxidation at a nickel-modified glassy carbon electrode-P. Southwell- Keely, W. Oungpiptat and P. W. Alexander Voltammetric behaviour of vitamin B1 (thiamine) at a glassy carbon electrode and its determination in multivitamin tablets using anion-exchange liquid chromatography with ampero- metric detection under basic conditions-J.P. Hart, Michael D. Norman and Stephen Tsang Epithermal neutron activation analysis of mosses used to monitor heavy metal deposition around an iron smelter complex-M. V. Frontasyeva and E. Steinnes Catalytic determination of iodide using the promethazine- hydrogen peroxide redox reaction-Masaaki Iwatsuki, Ashraf A. Mohamed, M. F. El-Shahat and Tsutomu Fukasawa Two approaches to the study of radiocaesium partitioning and mobility in agricultural soils from the Chernobyl area- Miquel Vidal, Maria Roig, Anna Rigol, Montserrat Llaurado, Gemma Rauret, Jan Wauters, Agnes Elsen and Adrien Cremers Gas chromatographic-mass spectrometric determination of chlorophenols in the urine of sawmill workers with past use of chlorophenol-containing anti-stain agents-Helena Kontsas, Christina Roesenberg, Pirkko Pfami and Paavo Jappinen COPIES OF CITED ARTICLES The Royal Society of Chemistry Library can usually supply copies of cited articles. For further details contact: The Library, Royal Society of Chemistry, Burlington House, Piccadilly, London W1V OBN, UK. Tel: +44 (0)71-437 8656. Fax: +44 (0)71-287 9798. Telecom Gold 84: BUR210. Electronic Mailbox (Internet) LIBRARY@RSC.ORG. If the material is not available from the Society’s Library, the staff will be pleased to advise on its availability from other sources. Please note that copies are not available from the RSC at Thomas Graham House, Cambridge.

ISSN:0003-2654    

DOI:10.1039/AN995200027N

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

Analyst, February 1995, Vol. 120 231 In-line, Titanium Dioxide-catalysed, Ultraviolet Mineralization of Toxic Aromatic Compounds in the Waste Stream from a Flow Injection-based Resorcinol Analyser* Miguel de la Guardia, Karim D. Khalaf, Berween A. Hasan, Angel Morales-Rubio and Vicente Carbonell Department of Analytical Chemistry, University of Valencia, 50 Dr. Moliner St., 461 00 Burjassot, Valencia, Spain A clean method was developed for the spectrophotometric determination of resorcinol. The method, based on the reaction between resorcinol and p-aminophenol (PAP), carried out in a flow system, involves an additional detoxification step based on the in-line TiOz-catalysed photodegradation of the indophenol dye formed and the remaining unreacted PAP. For this, after the measurement step the waste stream is merged with a Ti02 slurry (0.5 g 1-1 in 0.22 moll-1 HCI) and then passed through a UV photochemical reactor consisting of a PTFE tube (6 m X 0.8 mm La.) rolled on a UV lamp with a maximum irradiation wavelength of 254 nm.Under these conditions, the waste can be completely detoxified thus, providing 8 non-polluting method of analysis. Keywords: Flow analysis; resorcinol determination; spectrophotometry; photolysis; titanium dioxide Introduction Large amounts of phenolic compounds are produced as raw materials, providing different sources of environmental con- tamination. Other sources are refinery plants and the common use of a series of compounds, such as pesticides, which degrade to phenols, hence the determination of phenols in water is a priority task in order to control environmental pollution.Resorcinol is a phenolic compound used in tanning, manufacturing resins and dyes and in pharmaceutical formula- tions. It has many biological effects and can cause irritation of the skin and mucous membranes. The absorption of resorcinol can also cause methaemoglobinaemia, cyanosis, convulsions and death.' Resorcinol can be determined by different chromatographic techniques and many spectrophotometric methods have been reported for the determination of resorcinol in water samples. Among these methods, several reagents have been employed for the determination of resorcinol and other phenolic compounds, such as 4-aminoantipyrine (4-AAP), 3-methyl-2- benzothiothiazoline hydrochloride (MBTH) and p-amino- phenol (PAP), which produce coloured complex species which absorb at 410, 510 and 540 nm, respectively.2-3 In general, the analytical procedures developed have not taken into consideration that in addition to resorcinol, several of the reagents employed for its determination and the reaction products can be pollutants. However, it is essential to control the wastes from this kind of measurement in order to prevent laboratories engaged in this field of analysis from being additional sources of contamination.Hence, detoxi- fication of the waste must be taken into consideration as an * Submitted as a paper on Clean Analytical Methods. additional step in analyses of hazardous products that involve the use of toxic reagents. To decompose toxic products, different chemical, thermal, photochemical and microbiological methods, which have been proposed for the degradation of pollutants, could be incorpor- ated in the analytical measurements in order to develop clean analytical procedures.A variety of dangerous compounds can be destroyed by photodegradation processes carried out in the presence of Ti02 as a catalyst, providing photo-assisted catalytic pro- cedures, which are very efficient for the destruction of organic compounds. The formation of electron-hole pairs, under illumination with UV or visible radiation, effects the success- ful oxidation of several organic compounds on the TiOz surface Most photodegradation studies require the use of batch treatments which are tedious and difficult to automate. However, the development of flow injection (FI), now commonly applied in analytical chemistry,"J2 offers many possibilities for the automation of photodegradation processes.Previous studies carried out on in-line photochemical reactions demonstrated that PTFE tubing, instead of the typical quartz tubing, is very appropriate for providing sample irradiation13 and based on this post-column UV photochem- ical reactions have been employed in liquid chromato- graphy13J4 and for the determination of nitrogen in water by using an air-segmented flow system.15 In the photochemical degradation of pesticides using Ti02 as a catalyst, our earlier studies1618 indicated the possibility of using FI to carry out this kind of process in-line and faster than using the batch approach. This strategy could also be very useful in order to incorporate photodegradation reactors for the in-line detoxification of analytical wastes in order to provide cleaner analytical chemistry operations. Recently, we have developed a flow analysis spectropho- tometric method for the determination of resorcinol in waters3 by means of its reaction with p-aminophenol (PAP) to produce a complex compound that shows maximum absorp- tion at 540 nm.The method provides a limit of detection of 6.6 ng ml-1 (ppb) and a sample throughput of 300 h-1, and is a fast and convenient method for the determination of resorcinol in waters. In spite of all the advantages of the aforementioned method with regard to low limits of detection, reproducibility, economy and speed, it also has some disadvantages, which concern the final waste that certainly contains unreacted PAP and also the complex formed by the reaction between resorcinol and PAP.This mixture of phenolic compounds could be dangerous and hence detoxification of the final waste, by incorporating a photo-assisted catalytic unit after232 Analyst, February 1995, Vol. 120 the measurement cell, could prevent harmful environmental side-effects in laboratories that employ this spectrophoto- metric method. The aim of this work was to develop a clean analytical procedure for the spectrophotometric determination of resor- cinol by reaction with PAP, based on the in-line decomposi- tion of analytical wastes, and a series of studies were carried out in order to establish the optimum experimental conditions for the in-line degradation of resorcinol, PAP and the complex resulting from the reaction between resorcinol and PAP.Experimental Apparatus and Reagents A Hewett-Packard Model 8452A diode-array spectropho- tometer, with HP 89530A MS-DOS UV/VIS software, was used for the spectrophotometric measurements. A flow cell of 50 pl internal volume and 1 cm pathlength was employed for carrying out the FI absorbance measurements and to control the degradation of the organic molecules as a function of time. An ultraviolet lamp from Vilver Lourmet (Lyon, France), which provides UV radiation of 254 nm (220 V and 50 Hz), was employed as a light source to carry out the photo-assisted degradation. Two four-channel manifolds (see Fig. 1) were used. The first manifold [Fig.l(a)] was employed to study the hetero- geneous photocatalytic degradation of PAP, resorcinol and the reaction product between resorcinol and PAP. The other [Fig. l(b)], was used to carry out the spectrophotometric determination of resorcinol and the degradation of the waste simultaneously . In both manifolds, a Gilson Minipuls P2 peristaltic pump was used to transport the carrier streams, and a Rheodyne Type 50 rotary injection valve was incorporated in the flow UV lamp Resorcinol in NaOH TiO, +-I Detection U h = 190-800 nm I h = 540 NaOH TiO, 2 UV lamp h = 254 nrn I nm I U 1 Fig. 1 (a) Manifold for the study of the photo-assisted catalytic degradation of resorcinol, PAP and the reaction product between resorcinol and PAP. (b) Manifold for the flow-spectrophotometric determination of resorcinol with PAP.D, detector; R1 and Rz. reaction coils; and R3, photo-assisted catalytic degradation coil. injection system in order to inject standards and samples. In all instances, channel A was used to transport PAP and channel B to transport potassium metaperiodate. Channel C was employed to introduce standard solutions of resorcinol prepared in NaOH [Fig. l(a)], or to inject samples and standards into a sodium hydroxide carrier stream [Fig. l(b)]. Channel D was used to introduce a titanium dioxide slurry. Connections between any two channels were made with Y-shaped merging zones in order to ensure good mixing between reagents. Flexible vinyl tubing of 1.52 mm i.d. were used for the peristaltic pump, which allowed carrier flow rates from 0.5 to 4 ml min-1 in each channel to be obtained. The reaction coils were made of PTFE with an i.d.of 0.8 mm. All reagents were of analytical-reagent grade. Resorcinol was supplied by Aldrich (Steinheim, Germany), p-amino- phenol (PAP) by Fluka (Buchs, Switzerland), potassium metaperiodate and sodium hydroxide by Probus (Badalona, Spain) and titanium dioxide (anatase) powder, type P25, by Degussa (Frankfurt, Germany). From these reagents, appro- priate stock and working standard solutions were prepared as indicated in a previous paper .3 Titanium dioxide suspensions were prepared in distilled water or in acidified distilled water. General Procedure Using the manifold shown in Fig. 1(b), a 50 pg ml-1 PAP solution is continuously fed by channel A, while channel B is used to transport 0.0002 mol 1-1 K104 solution, in order to obtain the benzoquinoneimine form of PAP, by its oxidation, which is carried out in the reaction coil R1 (45 cm).A 0.006 moll-' NaOH solution is introduced by channel C in order to provide an appropriate alkaline medium for the reaction between resorcinol and PAP and also as a carrier for samples and standard solutions which are introduced by using a rotary valve with a loop of 500 p1. The reaction coil R2 (60 cm) provides the formation of the complex between the benzoqui- noneimine form of PAP and resorcinol. A Ti02 slurry is continuously introduced by channel D and mixed with the final waste obtained after the detector. The reaction coil R3 (600 cm), rolled on the UV lamp allows complete photodegra- tion of all the remaining toxic products, thus effecting detoxification of the waste.The carrier flow employed in all the channels is 0.8 ml min-1, which provides a sample throughput of 60 h-1 for an injection volume of 500 pl. Results and Discussion Photocatalytic Degradation of Resorcinol All the literature data indicate that photodegradation of organic compounds can occur in aqueous media owing to the presence of dissolved oxygen, which is necessary for the complete mineralization of the molecules. Therefore, a 40 pg ml-1 solution of resorcinol prepared in distilled water was subjected to photodegradation using the closed flow system indicated in Fig. 2(a), in which a 12 m PTFE coil was rolled around a UV lamp emitting at 254 nm in order to obtain a radial distribution of resorcinol and to be under the direct effect of the UV radiation.Fig. 2(b) shows that the absorption bands of resorcinol decrease gradually to zero when the solution is irradiated in the aforementioned manifold, the degradation yield of resorcinol being dependent on the irradiation time and hence complete mineralization of the high concentration of resorcinol assayed can be achieved in 17 min.Analyst, February 1995, Vol. 120 233 The degradation or resorcinol normally produces carbon dioxide and water according to the following equation: OH The complete mineralization of resorcinol is evidenced by the absence of the absorption bands after the irradiation time. However, a full degradation time of 17 min seems to be excessively long and not appropriate for use in flow systems, hence the decomposition of resorcinol was studied by using heterogeneous photo-assisted catalytic degradation in the presence of a Ti02 slurry in order to shorten the degradation time to be more suitable for the FI methodology, using the manifold indicated in Fig.l(a). The effects of several parameters on the degradation of resorcinol, such as Ti02 slurry concentration (from 0.5 to 2 g 1-1) prepared in different concentrations of HCI (from 0 to 7 rnol ]-I), flow rate of the streams (from 0.2 to 2 ml min-l) and length of the degradation coil R3 (from 6 to 18 m) were studied in the presence of potassium metaperiodate (0.0002 rnol 1-1) and sodium hydroxide (0.006 moll-1) in order to carry out the degradation under the same experimental conditions as used for the FI spectropho tome tric determination of resorcinol with PAP.The results obtained show that resorcinol can be degraded very rapidly under all conditions and it was confirmed, from the spectra of a solution of 20 pg ml-1 of resorcinol, before and after irradiation in the presence of TiOz (0.5 g 1-1, prepared in 0.22 rnol 1-1 HCI) at different flow rates, that quantitative degradation of this phenolic compound can be achieved using carrier flow values of the order of 0.4 ml min-1. 1.6 5 0.8 Time 1.5 200 250 300 WavelengtMnm \ v) 9 0.5 0 i 10 210 410 610 810 1010 1210 1410 Irradiation time/s Fig. 2 Photodegradation of resorcinol. (a) Closed flow system employed to study the degradation of resorcinol. (b) Change of the absorbance of a 40 mg 1-1 resorcinol solution as a function of irradiation time.A, 200 nm; B, 274 nm. The final spectra obtained for resorcinol solutions after photo-assisted catalytic degradation have absorption bands at 195 and 224 nm, which correspond to the absorption of sodium hydroxide and potassium metaperiodate solution. The absorp- tion band at 224 nm, which appeared during the degradation of resorcinol in the presence of KI04, does not correspond to the benzene ring,19 but to the potassium iodate produced during the oxidation process in the acidic medium. These aspects were confirmed experimentally by further investiga- tion of mixtures of potassium metaperiodate (0.0002 rnol I-I), NaOH (0.006 moll-1) and 0.5 g 1-1 solutions of Ti02 prepared in HC1 of different concentrations.After UV irradiation, the band at 224 nm began to appear and increased as the acidity of TiOz slurry increased. Further evidence about the nature of this band (224 nm) was obtained by studying the degradation of 20 pg ml-1 of resorcinol prepared in 0.006 moll-' NaOH, without KI04, in the presence of TiOz (0.5 g 1-1, prepared in 0.22 rnol 1-1 HCI); the spectrum obtained did not show the band at 224 nm, which indicates that this band appeared as a result of the reduction of KI04 to K103. Spectra obtained without KI04 showed a broad absorption band between 250 to 290 nm, which could correspond to the presence of unde- graded resorcinol, whereas in the presence of KI04 this broad band disappeared owing to the effect of KI04 on enhancing the complete degradation of resorcinol.Heterogeneous Photo-assisted Catalytic Degradation of p-Aminophenol The problems found in the photodegradation of PAP by means of simple UV irradiation agree with those reported previously for different procedures of degradation. Photolysis of PAP was studied at 77 K in an ethanolic solution and in an alkaline alcohol medium19 and it was confirmed that it gave compounds with different spectra assigned to p-H2NC6H40' and 'HNC6H40- radicals. On the other hand, PAP was pho tolysed2" in ethanol , diet h ylace tone-isopentane-e thanol and an aqueous alkaline solution at 77 K and electronic absorption spectra of the free radicals formed were measured. The UV irradiation of PAP in the mixture of organic solvents produced predominantly their cationic radical [H2NC6H40H]+' and the irradiation of the phenolate-type compound H2NC6H40-, which exists in alkaline solutions of H2NC6H40H, produced the neutral radical H2NC6H40'.A study carried out on the ozonization of PAP21 took into consideration the rate and the mechanism of the reaction 1.5 c [ 9 0.5 - 200 300 400 500 Wavelengthhm Fig. 3 UV spectra of 50 mg 1-1 of PAP prepared in distilled water before the heterogeneous photo-assisted catalytic degradation (1) and after degradation process (2) with 0.5 g 1-' T102 prepared in 0.22 rnol I-' HCI.234 Analyst, February 1995, Vol. 120 leading to the opening of the aromatic ring. In a dilute solution, the opening of the aromatic ring was achieved with an 03-to-phenol ratio of approximately 5 and the reaction rate depended on the amount of 03.Also, the degradation of PAP was influenced by pH. It has also been reported that organics containing nitrogen, such as amine or ammonium groups, are relatively difficult to oxidize because they exhibit a complex mechanism in which the degradation to inorganic compounds occurs very slowly in several steps, initially as ammonia and finally as nitrate.22 The heterogeneous photo-assisted catalytic degradation of PAP with a Ti02 slurry was subjected to an extensive study in the same way as for resorcinol. The results obtained showed that complete degradation of PAP, including the cleavage of the benzene ring, is a function of the irradiation time; Fig. 3 shows the absorption spectra of 50 pg ml-1 PAP before and after irradiation in the presence of a Ti02 slurry in 0.22 moll-' HCI . The results obtained indicate that 0.5 g I-' of Ti02 prepared in 0.22 rnol I-1 HCI, using a flow rate of 0.8 ml min-1, an R3 coil length of 12 m and room temperature give the best degradation results; 50 pg ml-1 of PAP can be completely mineralized, as can be concluded from the disappearance of the band at 252 nm (see Fig.3). Heterogeneous Photo-assisted Catalytic Degradation of the Indophenol Dye Formed Between Resorcinol and PAP The reaction of resorcinol (3) with PAP (1) takes place according to the following mechanism: OH 0 1 2 3 4 where PAP is oxidized by potassium metaperiodate to yield a very reactive benzoquinoneimine (2). The latter reacts very rapidly with resorcinol (3) in an alkaline medium through the electrophilic attack on C-4 of 3 to produce the corresponding indophenol dye (4), which shows an absorption maximum at 540 nm.The final waste from the above method contains a mixture of the indophenol dye formed between resorcinol and PAP and an excess of PAP. The heterogeneous photo-assisted catalytic degradation of the reaction product was studied in the same way as for resorcinol and PAP. The results obtained show that the use of UV irradiation without Ti02 has no effect on the mineralization of the indophenol dye, or on PAP, but on using the optimum conditions recommended for PAP degradation it can achieve complete destruction of all the compounds present in the final waste. Fig. 4 shows the absorption spectra of the indophenol dye produced from the reaction of 20 pg ml-1 of resorcinol and 50 pg ml-1 of PAP in the presence of 0.006 mol 1-1 NaOH and 0.0002 rnol 1-1 KI04, before and after UV irradiation at 254 nm in the presence of Ti02 (0.5 g 1-1 in 0.22 moll-1 HCI) and, as can be seen, the latter spectrum shows that the complete degradation of the indophenol dye, and also that of the excess of PAP, takes place under the previously indicated conditions.Method for the Determination of Resorcinol As mentioned before, the maximum flow rate that can be used is 0.8 ml min-1, when the photoreactor has an i.d. of 0.8 mm and a length of 6 m, which provides a very good degradation yield of the indophenol dye and the remaining PAP, and therefore the experimental conditions for the determination of resorcinol were modified to work at this flow rate; hence an R2 coil length of 60 cm was employed instead of the 300 cm employed previously.3 A series of standard solutions containing 2-8 pm ml-1 of resorcinol were prepared in 0.006 rnol 1-1 NaOH.The absorption measurements were carried out by using the manifold shown in Fig. l ( b ) , which was constructed in such a way as to permit the measurement of the absorption of the reaction product with PAP and also the complete mineraliza- tion of all the organic compounds that are present in the final waste from this method. The results obtained for calibration provided the regression line A = 0.007 + 0.0364 c, where A is the peak height of the FI recording, expressed in absorbance units, and c is the concentration of resorcinol in pg ml-1.The regression coefficient, r , corresponding to the above calibra- tion is 0.9993 and the limit of detection found under these conditions is 16 ng ml-1 of resorcinol, the relative standard deviation of four replicate analyses of a sample containing 4 pg ml-1 of resorcinol being 0.6% and the sample throughput 60 h-1. The above limit of detection is about double that found without incorporating the detoxification step, and the method provides a five times poorer sample throughput than that obtained under the optimum experimental conditions for the FI-spectrophotometric determination of resorcinol.3 However, the procedure developed provides a completely detoxified waste. 2.0 ,, I Conclusion From these studies it can be concluded that the procedure developed, although is slightly less sensitive and slower than the previous method,3 is clearly more environmentally accept- able, avoiding problems related to the toxicity of the laboratory wastes.It has been clearly established that the use of Ti02-catalysed UV mineralization of toxic aromatic com- pounds can be achieved in a flow stream, providing a simple means for the in situ detoxification of analytical wastes. 200 300 400 500 600 700 Wavelengthhm Fig. 4 UV/VIS spectra of the indophenol formed after the reaction of 20 mg I - * of resorcinol with 50 mg 1-1 of PAP in 0.006 rnol I-' NaOH and in the presence of 0.0002 rnol I - * KIOl before degradation (1) and after degradation (2) in the presence of TiOz. References 1 The Merck Index, Merck, Rahway, NJ, 10th edn..NJ, 1983. 2 Frenzel, W., and Oleksy-Frenzel, J., Anal. Chim. A m , 1992, 261, 253.Analyst, February 1995, Vol. 120 235 3 4 5 6 7 8 9 10 11 12 Khalaf, K. D., Hasan, B. A., Morales-Rubio, A., and de la Guardia, M., Talanta, 1994, 41, 547. Bard, J. A., Science, 1980,207, 139. Bard, J. A., J. Phys. Chem., 1982,86, 172. Gratzel, M., Energy Resources Through Photochemistry and Catalysis, Academic Press, New York, 1983. Izumi, I., Dunn, A. M., Wilbourn, 0. K., Fan, R. F., and Bard, J. A., J. Phys. Chem., 1980, 84,3207. Barbeni, M., Pramauro, E., Pelizzetti, E., Barfarelb, E., Gratzel, M., and Serpone, N., Now. J. Chem., 1984,8, 547. Barbeni, M., Marello, M., Pramauro, E., Pelizzetti, E., Vinceti, M., Borgarello, E., and Serpone, N., Chemosphere, 1987, 16, 1165. Serpone, N., Borgarello, E., Barbeni, M., Pelizzetti, E., Pichat, P., Hermann, M. J., and Fox, M. A., J. Photochem., 1987,36, 373 * RGiiEka, J., and Hansen, E., Flow Injection Analysis, Wiley, New York, 2nd edn., 1988. Valcarcel, M., and Luque de Castro, M. D., Flow Injection Analysis: Principles and Applications, Ellis Horwood, Chiches- ter, 1987. 13 Scholten, A. H. M. T., Welling, P. L. M., Brinkman, U. A. Th., and Frei, R. N., J. Chromatogr., 1980, 199, 239. 14 Vihlein, M., and Schwab, E., Chromatographia, 1982,15,140. 15 Kroon, H . , Anal. Chim. Acta, 1993,276, 287. 16 Pramauro, E., and de la Guardia, M., Richmac, 1991, IV (3) 63. 17 Peris-Cardells, E., Terol, J., Mauri, A. R., Pramauro, E., and de la Guardia, M., J. Environ. Sci. Health, 1993, 28,431. 18 Parreiio, R . , Morales-Rubio, A., and de la Guardia, M., J. Flow Anal., 1994, 11, 79. 19 Tsubomura, H., Kimura, K., Yamada, H., and Kato, M., Tetrahedron Lett., 1965, 47, 4217. 20 Kimura, K., Yoshinaga, K., and Tsubomura, H., J. Phys. Chem., 1976,71,4485. 21 Dore, M., Langlais, B., and Legube, B., Water Res., 1978, 12, 413. 22 Low, G. K., McEvoy, S. R., and Matthews, R. W., Environ. Sci. Technol., 1990,25,460. , Paper 410426IA Received July 12, I994 Accepted October 4, I994

ISSN:0003-2654    

DOI:10.1039/AN9952000231

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

Analyst, February 1995, Vol. 120 237 Photocatalytic Treatment of Laboratory Wastes Containing Aromatic Amines* Edmondo Pramauro and Alessandra Bianco Prevot Dipartimento di Chimica Analitica, Universita di Torino, Via P. Giuria 5, 10125 Torino, Italy Vincenzo Augugliaro and Leonard0 Palmisano Dipartimento di Ingegneria Chimica dei Processi e dei Materiali, Universita di Palermo, Viale delle Scienze, 90128 Palermo, Italy The photocatalytic degradation of several aniline derivatives present in aqueous solutions containing Ti02 suspensions was investigated. The process leads to the complete and fast decomposition (within about 1 h) of the pollutant molecules, promoted by oxidizing radical species formed at the irradiated semiconductor/water interface. The stoichiometric formation of C02 from the organic carbon was assessed, whereas other inorganic end-products were detected depending on the nature of the aniline substituents. Unstable hydroxyaromatic intermediates were also identified during the initial steps of the treatment.The primary degradation, which follows pseudo- first-order kinetics, changes with the aniline substituents and is strongly dependent on pH. Keywords: Photocatalysis; laboratory waste; degradation; pollutant; aromatic amine; aniline Introduction The problems related to the destruction of hazardous wastes are of actual interest, not only for people involved in industrial or agricultural activities, but also for those who operate in control laboratories, where more or less abundant stocks of contaminated solutions are usually produced and accumu- lated.Among the analytes and reagents of environmental con- cern, aromatic amines constitute a very important class, as they have been recognized as high priority pollutants. The presence of these compounds, generally at very low concen- tration levels, is often investigated in a large amount of environmental and waste samples. Aromatic amines can be also introduced as chemical reagents in analytical methods, usually as chelating ligands or coupling components in some spectrophotometric determina- tions. For example, the use of o-phenylenediamine and p-nitrosodiphenylamine (analysis of Pt metals), 2-aminoben- zenethiol (determination of Mo"'), benzidine (analysis of Cu and other metals) is mentioned in the literature.' Compounds such as 2,3-diaminonaphthalene (determination of selenium), N,N-diethyl-p-phenylenediamine (analysis of chlorine diox- ide), or N-( 1-naphthy1)-ethylenediamine (analysis of nitrite), are reported in current spectrophotometric methods applied to water and waste water analysis.2 When used as analytical reagents, the concentration of these compounds in the corresponding laboratory wastes may be relevant. The storage and successive destruction of such dangerous pollutants in authorized decontamination plants are usually expensive as they involve the meeting of very strict safety requirements.For this reason, the availability of suitable * Submitted as a paper on Clean Analytical Methods. procedures able to destroy the contaminants present in collected waste solutions immediately after the analytical determination steps, could offer a useful alternative.In this light, the photocatalytic method based on the use of suspen- ded semiconductor particles can be proposed as a relatively simple and low-cost procedure.3 When this approach is applied, either the complete decom- position of the target hazardous molecule or the absence of any toxic end-product must be assessed. Moreover, the identification of transient intermediates is also important as the possible formation of other toxic compounds during the process, even more dangerous than the initial substrate, cannot be excluded. For the above reasons, a very accurate analytical control of the reaction system becomes an essential requirement for a safe destruction of the pollutants.Here we report on the photocatalytic transformation of aniline and some para-derivatives, present at the mg 1-1 concentration level in aqueous solutions. The complete decomposition of such compounds was achieved in the presence of suspended Ti02 (anatase) particles, under simu- lated AM1 solar light. Sampling and analysis of the reaction system showed that a typical mechanism based on hydroxyla- tion and opening of the aromatic ring, with oxidation of the organic carbon to COZ, can be proposed. The nitrogen of the amino group is mainly transformed into nitrate and ammo- nium ion, whereas nitrite and cyanate anions were also identified during the treatment of 4-nitro- and 4-cyanoaniline, respectively. Moreover, halide ions were detected as typical end-products of haloanilines.Experimental Reagents and Materials The following high-purity aromatic amines were used as received: aniline, 4-methylaniline, 4-nitroaniline, 4-hydroxy- aniline (from Carlo Erba, Milan, Italy); 4-fluoroaniline, 4-bromoaniline, 4-cyanoaniline (from Fluka, Milan, Italy); 4-ethylaniline and 4-chloroaniline (from Aldrich, Milwaukee, WI, USA). Analytical-reagent-grade benzoic acid, sodium carbonate, sodium hydrogencarbonate, nitric acid, ammonium chloride, sodium nitrite and sodium hydroxide, were from Carlo Erba. Sodium p-hydroxybenzoate was purchased from Aldrich. Pure standards of the following compounds (Aldrich) were also used in the high-performance liquid chromatography (HPLC) experiments: 1,4-dihydroxybenzene (hydroqui- none) , 1,2-dihydroxybenzene (catechol), 1,3-dihydroxyben- zene (resorcine) , 1,2,4-trihydroxybenzene (hydroxyhydroqui- none) and 4-aminophenol. All solvents used were chromato- graphic grade (Lichrosolv, Merck, Elmsford, NY, USA).Doubly distilled water was filtered through 0.45 pm cellulose238 Analyst, February I995, Vol. 120 acetate membranes (HA, Millipore-waters, Milford, MA, USA) before use. Powdered Ti02 P25 Degussa (about 80% anatase form), having a surface area of 44 m2 g-1, was used in the photodegradation experiments. The powder was first ir- radiated for several hours in aerated aqueous dispersions in order to eliminate adsorbed organic matter and thoroughly washed with doubly distilled water to remove the inorganic ions. Subsequently, the filtered suspension was dried (at temperatures below approximately 75 "C) and resuspended by stirring before use.Stock solutions of each aniline derivative with concentra- tions ranging between 1 x 10-3 and 2 x 10-2 mol 1-1 (depending upon their solubilities) were prepared by dissol- ving the required amount of the compound in water. These solutions, protected from light, were stored at 5 "C. Irradiation Experiments Irradiations were performed in cylindrical Pyrex glass cells (4 cm id x 2.5 cm height) of 5 ml of aquous suspensions containing 2 x 10-4 mol 1-1 of each amine and the required amount of Ti02 powder (500 mg 1-I), using a 1500 W Xe lamp (Solarbox, from CO.FO.MEGRA, Milan, Italy) equipped with a 315 nm cutoff filter and simulating the AM1 solar radiation. The experiments were carried out under aerobic conditions, and the mean temperature within the cell was 60 "C.A simple scheme of the employed device is shown in Fig. 1. Analytical Determinations The concentrations of unreacted anilines were determined as follows: the cell irradiation was stopped at fixed times, the dispersion was filtered through 0.45 pm cellulose membranes (HA, Millipore), and the filtrate was immediately analysed by HPLC. Typically 50-100 pl of the filtered samples were injected into the chromatograph composed of an L6200 pump (Hitachi, Tokyo, Japan), an LA200 ultraviolet (UV) detector, and an RP-Cls 5 pm Lichrospher (Merck) 250 mm x 4 mm id column. Isocratic elution with acetonitrile-water (different solvent: water ratios were used depending on the analyte) was performed at 1 ml min-1.The amines were monitored at the wavelength of their maximum absorbance (in the range 225-270 nm), previously determined using a Uvikon 930 (Kontron, Zurich, Switzerland) spectrophotometer. The formation of C02 (one of the mineralization end- products) was followed by headspace gas chromatography (GC), according to a procedure described elsewhere.4 A Carlo Erba 4600 GC apparatus, equipped with a Hayesep Q 80/100 mesh (2 m x 6 mm id) packed column and a thermal conductivity detector, was used. The following working conditions were employed: flow rate, 30 ml min-1 (He hv Slurry \ Magnetic stirrer Fig. 1 Scheme of the cell used in the irradiation experiments (cutoff filters, present in the Solarbox between the lamp and the cell not shown).carrier); detector temperature, 150 "C (block) and 250 "C (filament); injector temperature, 130 "C; and column temper- ature, 110 "C. Blank runs, performed after long-term ir- radiation experiments indicated a very low C02 contribution of about 0.6 mmol 1-1, were used to correct the obtained data. The formation of halide anions (arising from the mineraliza- tion of haloanilines) was followed by suppressed ion chroma- tography, using a Biotronik IC5000 apparatus equipped with a 100 mm long X 4 mm id BTlAN column (Biotronik, Maintal, Germany). The eluent was a mixture of Na2C03 (1 mmoll-1) and NaHC03 (2 mmol 1-I), at a flow rate of 1 ml min-1. The formation of cyanate, nitrite and nitrate anions was followed by ion chromatography (IC), using a Metrohm 690 apparatus equipped with a Beckman (Fullerton, CA, USA) 110A pump and a Hamilton (Reno, NV, USA) PRP XlOO column (150 mm long X 4.1 mm id).The composition of the eluent employed was: benzoic acid 2 x 10-3 rnol 1-1 and sodium p-hydroxybenzoate 4 x 10-3 mol 1-1, dissolved in water-methanol (90 + 10 v/v), at pH 8.5. The elution was performed at a constant flow rate (1 ml min-1). For comparison purposes the nitrite analysis was also performed spectrophotometrically, using the Griess method.2 The absor- bance of the reddish azo-compound formed was measured at 525 nm, with a detection limit for NO2- of about 0.5 pg 1-1. The determination of ammonium ion was performed using the Nessler spectrophotometric method,2 measuring the absorbance of the corresponding reaction product at 400 nm against a blank.The calibration graph, prepared using NH4CI was linear in the NH4+ concentration range of 0.3-10 mg 1-1. Results and Discussion Substrate Decomposition (Primary Degradation) Irradiation of air-equilibrated aqueous solutions containing the investigated pollutants and the suspended semiconductor leads to the disappearance of these compounds. Starting from solutions containing 2 x 10-4 rnol 1-1 of substrate and 200 mg 1-1 of dispersed Ti02, at pH 5.5, the time required for complete decomposition of the investigated compounds was less than 1 h. These results are in agreement with previous findings concerning the destruction of other aromatic pollu- tants (having widely different chemical structures) present in water . 3 ~ 6 The sequence of events giving rise to the destruction process has been already examined in detail and is reported else- where.7-10 Basically, the Ti02 (anatase crystalline form) semiconductor has a bandgap energy (Ebg) of about 3.2 eV, with a corresponding light absorption threshold at 390 nm.This implies that, under simulated AM1 sunlight irradiation, only a small fraction (about 3%) of the incident light can be absorbed by the semiconductor particles promoting the electrons to the conduction band (CB) and leaving the corresponding valence band holes: A part of the charge carrier is lost through recombination, whereas a fraction of the carriers can rapidly migrate to the surface of the semiconductor particle, where they can be trapped as Tit1' (electrons) or as [TiIV-O- --TilV]-OH radicals (holes), giving rise to the following set of reactions, OZ(ads) indicating oxygen adsorbed on the Ti02 particles: 02(ads) -k e-(CB) + 02'-(ads) TP-OH- + h+ + TiIV/-OH TiIV-OH2 + h+ + TiiV/-OH + H+ (4) The -OH radicals are highly oxidizing species, capable of attacking the organic substrates.In aqueous acidic media (pHAnalyst, February 1995, Vol. 120 239 3) the 0 2 . - radical protonates forming the hydroperoxide radical HO2., which in turn gives rise to the formation of H202.11912 Absorption of UV light (A; 250-300 nm) by H202 or the interaction of this molecule with eTcBl can also originate -OH radicals. It was already clearly demonstrated that both molecular oxygen and water are essential components in photocatalytic reactions.13 Primary degradation kinetics The primary degradation of all the investigated compounds obeys pseudo-first-order kinetics, described by the following equation: -dcsubsldt = kobs csubs (5) where cs,bs is the concentration of each derivative and kobs is the observed first-order rate constant.According to eqn. (3, linear plots of -In clco versus time were obtained (see Fig. 2) from which slopes kobs can be evaluated. Table 1 reports the kobs values (together with the corresponding correlation coefficient, r) and the measured half-lifes (t3) of the examined compounds. It can be noted that the degradation kinetics vary depending on the substituent present on the aniline molecule. Alkyl groups and halogen atoms speed up the primary process, whereas the presence of nitrogen-containing substitu- ents reduces the reaction rate.All the corresponding kobs values are, however, grouped in a quite narrow range, with the sole exception of 4-hydroxyaniline. For this compound, in fact, primary degradation is significantly faster. Taking into account that the active species attacking the substrate are mainly radicals and that the reaction takes place at the semiconductorlwater interface or very near to it, the observed differences in reaction rates depend on the solute partitioning (between the bulk solution and the semiconduc- 2.0 I 1 tor surface), and on the presence of chemical groups or bonds more or less reactive towards the radicals. The increase of substrate hydrophobicity in alkyl- and haloanilines can favour their adsorption onto the particles, thus facilitating the reactions with adsorbed radical species.The formation of halide anions, which is more easy going from fluorine to bromine, could justify the rate sequence observed within the haloaniline group. The slower degradation rate of nitro- and cyanoaniline could be related to a lower reactivity of the corresponding aromatic rings towards the oxidizing radicals, due to the electrophilic nature of such substituents. However, the very fast degradation of 4-hydroxyaniline is not surprising as it has been already proven that hydroxylation of the aromatic ring favours further attack of the -OH species. Experiments performed at increasing pollutant concentra- tions showed a decrease in kobs. This effect, also reported in other photocatalytic studies, can be explained by assuming competition between reaction intermediates and substrate for the active sites of the semiconductor oxide.l4 Influence of p H on primary degradation The influence of pH on the photocatalytic degradation of aniline has been examined in detail. In particular, as expected, it was noted that a relevant decrease of the reaction rate occured at lower pH values (see Fig. 3). At pH 1.5, the half-life of aniline is about ten times longer than at pH 5.5, clearly indicating that the formation of the corresponding cation together with the presence of positively charged Ti02 particles (the isoelectric point is in the range 5-6 for this oxide) tends to repel the substrate from the catalyst surface. Moreover, the concentration of hydroxy radicals is lower in acid media and, thus, the primary degradation becomes strongly inhibited.Conversely, the pH increase favours the process because the yield of oxidizing radicals increases significantly in basic solutions. 0 5 10 15 20 25 30 Irradiation time/min Fig. 2 Kinetics of the primary degradation. A, 4-hydroxyaniline; B, 4-fluoroaniline; C, 4-ethylaniline, and D, aniline. Substrate concen- tration, 2 x moll-1; Ti02, 200 mg 1 - 1 ; cutoff filter, 315 nm; pH 5.5. Table 1 Kinetic parameters of primary degradation. Initial substrate concentration, 2 x 10-4 mol 1-1; Ti02, 200 mg I - I ; initial pH 5.5; cutoff filter, 315 nm Compound Aniline 4-Methylaniline 4-Ethylaniline 4-Fluoroaniline 4-Chloroaniline 4-Bromoaniline 4-Cyanoaniline 4-Nitroaniline 4-Hydrox yaniline tdmin 8.30 7.28 7.13 5.53 6.53 7.60 8.43 9.83 2.27 kobs x 102/min-l 8.35 9.50 9.70 12.50 11.50 9.11 8.21 7.04 31 .OO r [eqn.(511 0.998 0.997 0.999 0.990 0.9995 0.9995 0.999 0.9995 0.990 Photochemical contribution to the primary degradation The degradation of the investigated compounds in the absence of Ti02 was also investigated,, at fixed irradiation times, in order to evaluate the influence of the possible photochemical reactions. Depending on the structure of the examined compound and on the nature of the incident light, the photolytic contribution may be relevant, whereas the influ- ence of photolysis is strongly reduced if the 340 nm cutoff filter is used. Table 2 reports the percentage of substrate still present in the solution after 30 min irradiation when the semiconductor is absent.2.0 7 1.5 - - 2 p 1.0 3 0.5 0 15 30 45 Irradiation time/min Fig. 3 Variation of aniline degradation rate with the initial pH. A, pH 9.8; €3, pH 5.5; C , pH 3.2; and D. pH 1.5. Other experimental conditions as in Fig. 2.240 Analyst, February 1995, Vol. 120 Experiments performed on aniline under the above men- tioned conditions showed that the degradation becomes much slower and, in order to obtain reaction rates comparable with those measured using the 315 nm filter, the amount of Ti02 must be increased. Fig. 4 shows the effect of the semiconduc- tor concentration on primary degradation kinetics of aniline, at pH 5.5, using the 340 nm cutoff filter. It can be seen that the substrate half-life (about 5 min) is comparable to the previously reported value (about 8 min) after roughly doubl- ing the semiconductor concentration.However, a practical limit exists for the use of concentrated Ti02 suspensions in the reaction vessels owing to the relevant light scattering effects. Thus, in most practical systems the reported concentration of such a component is not higher than approximately 2 g 1-1. Formation of the Reaction End-products Although the transformation of each substrate occurs through the formation of (several) intermediate compounds, the formation of the end-products from the initial molecule is usually described by an over-all equation that remains valid after long-term irradiation. Working in the presence of an excess of oxygen and assuming complete mineralization, the following equation may be proposed for aniline: hv Ti02 C6H5-NH2 + 9 0 2 + 6 C02 + 3 H2O + H+ + N03- (6) Similar equations are valid for the other derivatives and, moreover, halide ions are obtained when haloanilines are degraded.However, the complete oxidation of nitrogen- containing groups present in aromatic molecules to N03- is not always found. Other inorganic end-products are usually detected together with this anion, indicating a more complex transformation scheme for these substituent groups in which reduction reactions involving nitrogen are probably operat- ing.15 Recent research work performed on a series of nrtroaromatic compounds clearly confirmed the presence of such reduction steps.16 Mineralization of organic carbon to COZ The complete oxidation of the organic carbon to C02 in less than 1 h was demonstrated for all the investigated compounds, thus indicating the feasibility of the proposed degradation method.However, the formation of C02 is a slow process if compared with primary degradation, and this implies that the reaction proceeds through the formation of other interme- diate organic species. In fact, after about 10 min irradiation, the amount of C02 formed does not exceed approximately one sixth of the stoichiometric value, whereas under the same irradiation conditions, more than one half of the initial substrate has been decomposed. The presence of some organic intermediates arising from the hydroxylation of the aromatic ring has been confirmed via HPLC analysis. Fig. 5 shows the CO2 formation profile for aniline and two alkyl derivatives.It can be seen that the presence of the alkyl groups slightly reduces the CO2 formation rate because, in addition to the aromatic ring, the alkyl chain must also be attacked by the active radicals. The formation of the stoi- chiometric amount of C02 (plateau region) is reached after about 45-50 min for aniline and at longer times for the alkyl derivatives. Conversely, the C02 formation rate is practically the same for derivatives having no alkyl substituents. Formation of halide ions It appears to be characteristic that hydroxyl radicals add to the halo-organic substrates displacing the corresponding halogen Table 2 Effect of photolytic processes after 30 min irradiation in Solarbox. Initial substrate concentration, 2 x 10-4 mol 1-1 Percentage of residual aromatic amine Compound h 3 315 nm h 2 340 nm Aniline 4-Me th ylaniline 4-Ethylaniline 4-Fluoroaniline 4-Chloroaniline CBromoaniline 4-Cyanoaniline 4-Nitroaniline 4-H ydroxyaniline 88.0 88.5 80.0 56.0 46.0 78.5 96.0 96.0 85 .O 97.5 97.0 94.5 81 .o 77.5 87.5 99.0 99.5 96.0 2.0 I I n C , 0 15 30 45 60 Irradiation time/min Fig.4 Effect of semiconductor concentration on aniline degradation at DH 5.5. A. 100: B. 200: and C. 450 DDm (semiconductor). 16 t % 8 Y- .el .:r 8 0 15 30 45 60 75 Irradiation timehiin Fig. 5 C, 4-ethylaniline. Other experimental conditions as in Fig. 2. Kinetics of C02 formation A, aniline; B, 4-methylaniline; and 2.0 1.5 I - - E po 1.0 0.5 : 0 20 40 60 80 Irradiation time/min Kinetics of halide anion (X-) formation. A, 4-fluoroaniline; Fig.6 B. 4-chloroaniline: and C. 4-bromoaniline.Analyst, February 1995, Vol. 120 24 1 radical, which is in turn transformed into the corresponding halide via the reduction of .X by the conduction band electrons: ax + e-CB + x- Fig. 6 shows that the stoichiometric formation of fluoride is faster than the formation of chloride, which is, in turn, faster than bromide. These findings are in agreement with the tendency of each halogen atom to form the corresponding anion. The kinetics of halide formation are comparable to those of COZ formation, both processes being faster than nitrogen mineralization. (7) Formation of nitrogen-containing inorganic products Most of the experiments were performed on aniline and it was found that the presence of a large excess of oxygen in the reaction cell is a fundamental parameter.In fact, very low amounts of nitrate were obtained working in closed cells (even after several hours irradiation), whereas oxidation became faster if the cells were opened at regular time intervals (typically every hour). It must be underlined that ammonium ion has also been detected in these experiments, thus indicating that oxidation-reduction processes of nitrogen take place simultaneously in the system (see Fig. 7). As the measured final pH in the irradiated cell is about 3.4 (starting from an initial pH of 5.5), there is practically no risk of ammonia loss during cell opening. Similar profiles were obtained for the other derivatives. For example, after approximately 500 min irradiation, the 'i - 1.5 c!! 0 150 300 450 600 750 Irradiation time/min Fig.7 Formation of nitrogen-containing products during the photo- catalytic degradation of aniline. A, NHZ; B, NO;; and C, NO; (closed cell). The dashed line at the top of the figure represents the stoichiometric amount of nitrogen. 2.25 F I - 0.75 J 0 150 300 450 600 Irradiation time/min Fig. 8 Nitrite formation during the photocatalytic transformation of 4-nitroaniline. A, NH:; B, NO,; and C, NO,. measured concentration of NO3- in the reaction solution was in the range 7-8 x 10-5 moll-' for aniline, 4-ethylaniline and 4-chloroaniline. After the same irradiation periods, the ammonium ion determined was in the range 6-7 X 10-5 moll-1, thus implying that about 25-30% of the total nitrogen must be present in other forms.These results are in agreement with those reported in studies concerning the photocatalytic transformation of other nitrogen-containing compounds and some authors suggested the possible formation of hydroxylamine as reaction pro- duct. 16717 Moreover, the formation of gaseous compounds (for example N2) from the oxidation of the above hypothesized intermediate cannot be excluded, but the detection of such products is difficult' under the reported experimental condi- tions. It must be noted that there is no evidence of nitrite formation (at least within the sensitivity limits of the applied analytical methods) during the degradation of the investigated compounds, with the sole exception of nitroaniline (see Fig. 8). This result is in agreement with recent studies concerning nitroaromatic compounds.14316 Another peculiar behaviour was exhibited by 4-cyanoani- line which, in addition to ammonium ion and nitrate, also 0 50 100 150 200 250 0 2 4 6 8 10 Irradiation time/min tdmin Fig. 9 (a) Degradation of A, 4-cyanoaniline and B, intermediate formation of cyanate ion. (b) Ion chromatography peaks: A, cyanate; and B. nitrate. r I - E 10 20 30 40 50 60 Irradiation time/rnin 10 0 tdmin Fig. 10 (a) Detection and evolution of hydroxyaromatic intermedi- ates during the photocatalytic degradation of aniline: A, 4-hydroxy- aniline; B, 1,3,4-trihydroxybenzene; and C, aniline. (b) HPLC peaks: A, aniline; B, 4-hydroxyaniline. and C. 1,3.4-trihydroxybenzene.242 Analyst, February 1995, VoL. 120 showed the presence of cyanate as an intermediate.This compound, which was not previously found in other reported experiments, confirms that the transformation cycle of nit- rogen is strongly dependent on the nature of the nitrogen atoms or groups present in the pollutant molecule. The concentration profile of this intermediate [illustrated in Fig. 9(a)] shows a maximum after about 100 min, when 4 cyanoaniline is no longer present in the system. After about 200 min cyanate is, in turn, completely degraded. The Fig. 9(b) shows the observed IC chromatographic peaks corre- sponding to nitrate and cyanate ions present in solution after 50 min irradiation. Presence of Hydroxyaromatic Intermediates The HPLC pattern of aqueous aniline after photo-oxidation [see Fig. 10(b)] shows a group of peaks at retention times shorter than that of the starting substrate, which completely disappear after about 55 min of irradiation.The possible chemical identity of some of these compounds was investi- gated by comparing their retention times with those of different pure standards and, in particular, peaks B and C were assigned to 4-hydroxyaniline and 1,2,4-trihydroxyben- zene, respectively. The presence of polyhydroxyaromatic compounds, already observed during the degradation of other previously investigated aromatic moIecules,13,14,18~*Y confirms the nature of the process. It is also known that, after the formation of trihydroxybenzenes, the reaction proceeds via the ring opening and the detection of the corresponding products becomes more difficult. The concentration profiles of the intermediates formed during the aniline transformation are shown in Fig.10(a). Blank experiments performed on solutions containing the corresponding pure standards (each at the concentration of the corresponding maximum) showed the same kinetic pro- file, thus supporting the previously proposed assignment. In some instances, for irradiation times in the range 10-20 min, the appearance of a transient yellowish colour was observed. As aromatic amines and phenolic products are simultaneously present at that time (as found during the analysis of the intermediates), coupling reactions between them can occur. However, these hypothesized intermediates are further degraded as the solution again becomes completely colourless after about 30 min of irradiation. Conclusion The experiments performed indicated that photocatalysis over suspended Ti02 particles is an accessible, suitable and cheap degradation method for the destruction of residual aromatic amines present in laboratory wastes. Under the reported conditions, all of the examined aniline derivatives were degraded in less than 1 h, irrespective of the nature of the substi tuen t present .The final products, arising from the more or less complete mineralization of the initial pollutant, are not dangerous and the detected intermediate compounds do not accumulate in the reaction vessel, but are themselves rapidly degraded by the radical species formed during the irradiation. The presence of abundant oxygen in the reaction cell is important, especially if a more complete oxidation of nitrogen is desired.The use of direct solar light or simulated solar light containing low percentages of the UV component (as in the experiments performed with the 340 nm cutoff filter) is also possible, taking into account that the degradation kinetics becomes slower in these situations. Optimization studies performed on larger volume photo- reactors are actually under investigation in order to scale up the proposed treatment method. Financial support from MURST (Rome), CNR, and EEC Contract STEP-CT90-0106-C (DSCN) is gratefully acknow- ledged. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 References Photometric Determination of Traces of Metals. Part I , ed. Sandell, E. B., and Onishi, H., Wiley, New York, 1978. Standard Methods for the Examination of Water and Wastewater, ed.Clesceri, L. S., Greenberg, A. E., and Rhodes Trussel, R., APHA-AWWA-WPCF, Washington D.C., 17th edn., 1989, ch. Ollis, D. F., Pelizzetti, E., and Serpone, N., in Photocatalysis. Fundamentals and Applications, ed. Serpone, N., and Pelizzetti, E., Wiley, New York, 1989, pp. 603-637. Pelizzetti, E., Minero, C., Maurino, V., Sclafani, A., Hidaka, H., and Serpone, N., Environ. Sci. Technol., 1989, 23, 1380. Mills, A., Davies, R. H., and Worsley, D., Chem. SOC. Rev., 1993, 417. Pelizzetti, E., Minero, C., and Pramauro, E., in Chemical Reactor Technology for Environmentally Safe reactors and Products, ed. De Lasa, H. J., Kluwer, Dordrecht, 1993, pp. 577-607. Howe, R. F., and Gratzel, M., J. Phys. Chem., 1987,91,3906. Lawless, D., Serpone, N., and Meisel, D., J. Phys. Chem., 1991, 95, 5166. Okamoto, K., Yamamoto, Y., Tanaka, H., Tanaka, M., and Itaya, A., Bull. Chem. SOC., Jpn., 1985, 58, 2015. Al-Ekabi, H., and Serpone, N., J. Phys. Chem., 1988,92,5726. Cundall, R. B., Rudham, R., and Salim, M. S., J. Chem. SOC., Faraday Trans. I , 1976, 72, 1642. Hermann, J . , and Pichat, P., J. Chem. Soc. Faraday Trans. I , 1980, 76, 1138. Barbeni, M., Pramauro, E . , Pelizzetti, E., Borgarello, E., Gratzel, M., and Serpone, N., Nouv. J. Chim., 1984, 8, 546. Augugliaro, V., Palmisano, L., Schiavello, M., Sclafani, A., Marchese, L., Martra, G., and Miano, F., 1. Appl. Catal., 1991, 69, 323. Low, G. K. C., McEvoy, S. R., and Matthews, R. W., Environ. Sci. Technol., 1991, 25, 460. Minero, C., Pelizzetti, E., Piccinini, P., and Vincenti, M., Chemosphere, 1994, 28, 1229. Mozzanega, H., Herrmann, J . M., and Pichat, P., J. Phys. Chem., 1979, 83, 2251. Barbeni, M., Morello, M., Pramauro, E., Pelizzetti, E., Vincenti, M., Borgarello, E., and Serpone, N., Chemosphere, 1987, 16, 1165. Pramauro, E., Vincenti, M., Augugliaro, V., and Palmisano, L., Environ. Sci. Technol., 1993, 27, 1790. 3, pp. 135-137; ch. 4, pp. 79-80; ch. 4, pp. 117-120. Paper 41064408 Received October 21, 1994 Accepted October 28, 1994

ISSN:0003-2654    

DOI:10.1039/AN9952000237

出版商:RSC    

年代:1995

数据来源: RSC

摘要:

Analyst, February 1995, Vol. 120 243 Seasonal and Areal Variations of Polycyclic Aromatic Hydrocarbon Concentrations in Street Dust Determined by Supercritical Fluid Extraction and Gas Chromatography-Mass Spectrometry* Yu Yang and Wolfram Baumannt Institute of Inorganic Chemistry and Analytical Chemistry, University of Mainz, 55099 Mainz, Germany Twenty-four street dust samples were collected from highways, urban streets, a gasoline station, pedestrian tunnels, a civil house and a car park building in some German cities. Polycyclic aromatic hydrocarbons (PAHs) were extracted from these samples with supercritical COz and determined by gas chromatography-mass spectrometry. The PAH concentrations showed distinct variations with the sampling area and the sampling season. In winter, the street dusts were contaminated by PAHs about 2-12 times more than in summer.Fluoranthene, pyrene and phenanthrene always exhibited the highest concentrations, independent of the total PAH concentration, and thus may be used as indicators of PAH pollution of street dusts. Keywords: Supercritical fluid extraction; supercritical carbon dioxide; polycyclic aromatic hydrocarbon; street dust Introduction Polycyclic aromatic hydrocarbons (PAHs) in the environment have received much attention because of both their continuous emission from combustion and their biological activities,' such as toxicity, mutagenicity and carcinogenicity. Most of the previous investigations on PAHs in the environment have been concentrated on airborne particles, and little work has been carried out on street dusts.2" As a first step in an analytical procedure for PAHs, extraction of the investigated environmental samples is necessary.Liquid-liquid (Soxhlet or sonication) extraction and subsequent separation by column chromatography or by adsorption onto special sorbents are widely employed for this purpose. However, such extractions often require large volumes of solvent, which may be toxic and/or expensive, and they often need several hours to even several days to yield acceptable although often incomplete recoveries of some target anal ytes. The recovery of many compounds from complex samples should increase with decreasing viscosity. This was the main impetus to developing procedures that incorporate supercritical fluid extraction (SFE) steps7 and subsequently, applications of this technique also to the determination of PAHs in environmental particulates have been reported.8-12 For laboratory work, generally the application of C02 is preferred over other available fluids as it is non-toxic and its critical point data are easily accessible: at 40 "C and 200 bar the density of C02 is of the order of that of non-polar organic liquids, as is the polarity.However, the viscosity is much * Submitted as a paper on Clean Analytical Methods. 't To whom correspondence should be addressed. lower. Therefore, C02 under these conditions has the solvent power of at least hexane but shows much better mass transfer characteristics as an extraction medium. Hence it should be the ideal solvent for PAHs in street dust.In addition to the aforementioned advantages of C02 as a non-polar solvent, it is a non-toxic and non-ecotoxic gas that does not necessarily create an additional load for the environment as it can be produced from the CO;! content of the atmosphere or from natural CO2 sources. These advan- tages of C02 as a low-viscosity, low polarity solvent and its physiological and ecological advantages make it an ideal candidate solvent for use in clean analytical methods. Extraction and determination in this investigation were performed by off-line SFE followed by gas chromatography-mass spectrometry (GC-MS) , which for the purpose of this work is a more flexible and simpler technique than on-line coupling to, e.g., GC,1* liquid chromatography13 or even supercritical fluid chromatography.14 Experimental Sampling and Samples Street dust samples were collected between April 1990 and December 1991 using a battery-powered vacuum cleaner from a farm road, a civil house, highways, urban streets, a gasoline station, a car park building, an industrial area and pedestrian tunnels in Mainz, Berlin , Frankfurt/Main, Hannover, Wies- baden and Mannheim. The dusts were sampled directly from the street side, unless stated otherwise. All samples were sieved through a 100 pm metal filter. Some samples were further classified into three classes: < 50, 50-100 and 100-500 pm. In the Mainz district some samples were collected from the same sampling site in different seasons of the year. Table 1. shows the sampling date and site for each sample.Samples were stored for different times (average 6 months) at -4 "C in small glass bottles closed by a PTFE foil capsule until analysis. In order to prepare well defined but similar model samples, real samples were extracted for 3-5 h with pure supercritical CO2 at 40 "C and 200 bar, and then a second time for another 3-5 h using supercritical COZ at 40 "C and 200 bar saturated with methanol (10% v/v). When used as blanks in the standard extraction procedures, such samples turned out to be real blanks (no PAHs were found in this matrix). A 1 g amount of this matrix was then spiked with 100-300 ng of each target PAH, mixed well and the solvent was allowed to evaporate at low temperature (4-10 "C). These model samples (blank matrix spiked with PAHs) were stable for several weeks in a refrigerator.Some were analysed again after ageing for 3 months and no significant change in the recovery was found.244 Analyst, February 1995, Vol. 120 Compounds The following PAHs were found in a first screening experi- ment on a real dust sample, using GC-MS in the scan mode, and were therefore followed in this study: acenaphthylene (Any), acenaphthene (Ane), fluorene (Flr), phenanthrene (Ph), anthracene (A), 2-methylphenanthrene (2-MePh), 2-methylanthracene (2-MeA), 1-methylphenanthrene (1- MePh), 2-phenylnaphthalene (2-PhyN), 3,6-dimethylphenan- threne (3,6-DiPh), 2,7-dimethylphenanthrene (2,7-DiPh), fluoranthene (F), pyrene (P), benzo[ghi]fluoranthene (BghiF), benz[a]anthracene (BaA), chrysene (Ch), anthracene-9,lO-dione (9,lO- Adio) 7H-benz[ delanthracen-7- one (7H-BA-7-0) and Benzo[b]naphtho[ 172-d]thiophene (BbNoThio).Standard PAHs were supplied by Promochem, Amchro Chromatography, Johnson Matthey, Aldrich and Merck. Table 1 Sampling date (year/month/day) and sampling site for each sample Sample No. Sampling date s1 s2 s3 s4 s5 S6 s7 S8 s9 s10 s11 s12 S13 S14 S15 S16 S17 S18 S19 s20 s2 1 s22 S23 S24 90/04/04 90/04/05 90/04/05 90/05/03 90/05/14 90/05/2 1 90/05/24 90/07/04 90/07/13 90/07/17 90/08/26 90/08/26 90/09/06 9011 011 0 91/01/10 91/01/10 91/01/15 91/03/25 91/04/15 91/05/09 9 1/05/15 91/05/15 91/05/15 9 1 / 12/27 Sampling site East Berlin. Heinrich-Mann-Strasse West Berlin, in front of Zoo railway station Hannover, in front of the main railway station Mainz, on the bridge over the main railway station, above S8 Mannheim, at the centre of the pedestrian subway to the main railway station station 16 km from Mainz), Spielbergstrasse pedcstrian subway, under the bridge over the main railway station Mainz-Mombach, industrial area, Rheinallee, under the railway bridge to Wiesbaden Mainz, Binger Strasse, on the crossway with the tramway Mainz-Lerchenberg, Koblenzer Strasse, under the A60 highway bridge strasse, on the A60 highway, above s11 parking lot 122-123 Mainz, Binger Strasse, in the DEA gas Stadecken-Elsheim (a small town Mainz, on a rail in a half-sided open Mainz-Lerchenberg, Koblenzer- Frankfurt airport, on the floor of Same as S9 Same as S11 Same as S 12 Same as S9 Same as S8 Wiesbaden, in the pedestrian tunnel in front of the main railway station, 2-10 m from the entrance (station side) Same as S9 Mainz-Bretzenheim, 300 m from Koblenzer Strasse, on a small farm road Same as S12 Same as S11 Mainz-Hartenberg, Jakob-Steffan- Strasse 39, dust from a flat on the second floor Procedures SFE The supercritical fluid extractions were performed using a laboratory-made SFE system.Fig. 1 shows the scheme of this experimental set-up, with all necessary instrumental details. The main parts are a membrane compressor controlled for any settable pressure between 60 and 200 bar (Nova Swiss Model 555.0020), a laboratory-made temperature-controlled water-bath, an extraction cell (Bischoff-type column, 12.5 cm x 2 cm i.d.) and a series of miniature columns (18 mm x 1.5 mm i.d., slurry packed with RP-18, 3 ym particles) which serve both as flow resistors and as sample collectors. The samples (1 or 3 g) were packed inside a piece of soft paper (e.g., Kleenex) and then positioned roughly in the centre of the extraction cell.The remaining cell volume was filled with glass balls. A 20 1 volume of C02 was used for all ex tractions. As an additional advantage, the series of miniature columns provided a pre-selection with sample precipitation in the different columns of the series, according to the solubility of the sample components at the pressure of the column considered. Details of this method were described pre- viously.1s For further GC-MS analysis, analytes from the single miniature columns were rinsed using about 1 ml of toluene by an HPLC pump (Bischoff Model 2200).This eluent could then be analysed by GC-MS. GC-MS A Hewlett-Packard H P 5890A gas chromatograph and a Hewlett-Packard HP 5970 mass spectrometer with electron impact ionization (70 eV) and helium as carrier gas were used. Separation was carried out with on-column injection onto a 50 m x 0.25 mm i.d. capillary column (Macherey-Nagel, SE-54-CB-0.25). Qualitative analyses were performed in the SCAN mode, from 35 to 350 u. Quantitative analyses were performed by MS in the selected ion monitoring (SIM) mode. For this purpose characteristic ions were observed that were monitored in nine groups of four to eight ions, with a dwell time of 50 ms for each ion. Table 2 shows the analytical SIM conditions. A certified PAH standard solution in toluene that contained 100-200 ng ml-1 of each PAH was used.Two internal standards (F-HCH and Mirex) were added at 144 and 168 ng ml-1 to each standard and to each sample solution. Fig. 1 Schematic diagram of the experimental set-up: CL, C 0 2 cylinder; MC, membrane compressor; PI, manometer with maxi- mum/minimurn pressurc-control switches; V1, pressure-regulating valve; P2, fine manometer; V2 and V3. needle valves; T, water-bath thermostat; E, extraction cell; COL, series of miniature columns; F, flow meter; and GC-MS, off-line transfer to GC-MS analysis.Analyst, February 1995, Vol. 120 245 Selectivity of Extraction Process Under the extraction conditions (40 "C, 200 bar) used, CO2 is a powerful eluent for non-polar PAHs. As the solubility of PAHs is very good under these conditions precipitation occurred only on the last three miniature columns of a series of nine or ten columns whereas more polar but still C02-soluble compounds precipitated on the first miniature columns.This behaviour is consistent with that found previously with non-polar or medium-polarity pesticides. 15 Hence, only three columns had to be eluted with toluene and the eluate was almost free from interfering compounds, owing to the selectivity of the extraction power of C02 and of the fractionated precipitation onto the miniature columns. Chromatographic Conditions The selected ion chromatogram was used to optimize the extraction steps and the chromatographic conditions, such as the temperature programme shown in Table 3. Fig. 2 shows an example of the selected ion chromatogram of a real dust sample.This chromatogram shows the high selectivity of the final procedure with respect to the non-polar Table 2 Selected ions, divided into nine groups, the retention times (tR) and the recoveries of which are given as average values with standard deviations, from each of three complete SFE-GC-MS experiments on model dust samples Compound* Any Ane Flr Ph A E-HCH 2-MePh 2-MeA 1-MePh 9,lO- Adio 3,6-DiPh 2,7-DiPh F P BghiF BbNoThio BaA Ch Mirex 2-PhyN 7H-BA-7-0 Ion mass 150/152 1521154 1631166 17611 78 1761178 18312 19 189/192 189/192 189/192 202/204 1801208 1911206 191/206 2001202 200/202 2241226 2321234 226/228 2261228 2021230 2721274 * For full names, see text. Group 1 2 3 4 5 6 7 8 9 tRlrnin 15.4 16.2 18.9 26.5 27.1 28.6 32.3 32.8 33.7 35.8 36.1 38.0 38.8 41.4 44.7 60.6 61.2 62.9 63.5 65.0 68.3 Recovery (% ) 91 k 11 85 k 9 9 6 f 11 102 f 11 98k 11 92 +- 10 84+ 10 92 k 10 86 f 9 99+ 11 96+ 11 9 4 f 11 93 k 12 90 k 12 62 f 8 60 f 7 6 4 k 8 61k8 71 + 19 ~- ~ Table 3 GC temperature programme TemperaturePC Timelmi n 0-4 4-4.71 4.71-5.5 1 5.5 1-20.89 20.89-41.72 41.73-54.22 54.23-57.3 57.3-70 Initial 90 90 140 180 200 225 250 270 Final 90 140 180 200 225 250 270 270 PAHs and some other non-polar compounds.Almost all peaks not marked were identified as polychlorinated biphenyls, which will not be discussed in this paper. Recovery The recoveries of PAHs were determined using the model samples described above, which were extracted with 30 1 of C02 under the above mentioned conditions. Table 2 gives the recoveries of all 19 PAHs with standard deviations, calculated from three independent complete extraction and determina- tion procedures.For smaller and more volatile PAHs the recoveries are nearly loo%, in contrast to the more polar or the larger PAHs, with recoveries as low as 60-70%. As with all analytical work on real matrices, the question arises of how the measured recoveries can be applied to the determination of PAHs in real samples. As mentioned above, the twofold extraction with methanol as modifier did not produce any further target analytes, and the same was true with hexane as the eluent. Hence applying the recoveries to the evaluation of data from real samples probably does not introduce additional errors. This speculation is further sup- ported by the fact that the very non-polar PAHs do not show a good interaction with the much more polar sites of dust, and so also will not sit in pores, etc.Further evidence for complete extraction comes from the fact that aged model samples also yielded around 100% recovery. This is also consistent with independent observations that only polar compounds or compounds with polar groups (pesticides) exhibit the problem of undissolvable residues. However, the PAH concentrations found in real dust samples in this study should provide good indications of the minimum PAH concentrations. Results Table 4 shows the results for the determination of each PAH in 24 samples. In all samples investigated, PAHs were found and the total concentration (sum of all 19 PAHs) varied from a few to a few hundred pg g-1, depending on sampling area and season.It is worth-while noting that the size distribution is approximately the same for all dust samples except for S8 and S18. These samples were collected from the frame of a rail in a pedestrian subway, which obviously retains smaller particles better than larger ones, which probably are blown off, as the subway is exposed to wind. Table 5 shows the particle mass distribution for four selected samples, sieved into three fractions. Of special interest is that the concentrations of fluoran- thene, pyrene and phenanthrene, although varying from i I 15 20 25 30 35 40 45 50 55 Timelmin Fig. 2 Typical selected ion chromatogram of a real dust sample.246 Analyst, February 1995, Vol. 120 sample to sample, are the highest in almost all samples.Hence they may be used as indicators of PAH pollution. Discussion Areal Variations of PAH Concentrations As there is a seasonal variation that is discussed in the next section, the discussion here is concentrated on the samples taken in spring. Table 4 reveals that there are samples with total PAH concentrations of less than 5 pg g-1 (S4, S5, S7, S21, S22 and S23), an intermediate group containing 6-16 yg g-1 ( S l , S2, S3 and S19) and another group containing 18-115 pg g-1 (S6, S18 and S20). As expected, the lowest values were found in a small town (S7), in the centre of a 150 m pedestrian tunnel ( S 5 ) and on a farm road (S21). However, one would not expect that samples S4, S22 and S23 would also show relatively small PAH loads as there was heavy traffic at these locations. This finding indicates that the PAHs possibly accumulate on dust particles and thus show lower than expected concentrations at locations where the mean standing time of dust particles is low owing to exposure to wind, which is the situation with S4, S22 and S23.However, the extremely highly loaded site S18 is a location where dust may stay and even accumulate for a long time. Of course, the gas station sample S6 shows a high PAH concentration, probably owing to direct pollution from spilled fuels. Seasonal Variations of PAH Concentrations The PAH concentration was observed at four sampling sites in Mainz at different times of the year. Fig. 3 shows the observed Table 5 Relative mass distributions (%) of four dust samples, classified into three size fractions Size fraction diametedpm Sample <50 50-100 100-500 s11 7.6 26.0 66.4 S14 7.9 36.5 55.6 S18 33.8 58.5 7.7 S19 10.4 28.8 60.8 Table 4 Concentrations (ng g-1, determined from one aliquot of each sample) of 19 individual PAHs and the total PAH concentration (rounded to two significant figures) in street dust from sampling sites S1-S24 PAH* Ane F1 r Ph A 2-MePh 2-MeA l-MePh 3,6-DiPh 2,7-DiPh F P BghiF BaA Ch 9,lO-Adio BpNoThio Total Any 2-PhyN 7H-BA-7-0 Any Ane F1 r Ph A 2-MePh 2-MeA 1-MePh 3,6-DiPh 2,7-DiPh F P BghiF BaA Ch 9.10-Adio BbNoThio Total 2-PhyN 7H-BA-7-0 S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 15 16 38 72 350 180 1300 2400 220 120 400 740 120 32 25 440 110 550 38 290 53 170 1200 2400 1100 1800 250 220 540 530 1500 1400 87 520 - 130 91 130 7400 12000 24 47 77 940 110 400 53 240 390 210 140 1600 1 400 290 400 1 200 290 180 130 8 100 17 57 40 320 73 260 24 270 270 91 180 760 670 39 140 210 230 53 36 3 700 8 73 64 480 71 110 20 35 180 98 72 260 160 3 9 19 20 48 1 1700 55 210 870 3 600 540 4 700 460 2 300 3 200 2 200 1500 2 900 3 300 200 640 1 600 2 700 310 70 31 000 29 36 -t 220 20 400 160 4700 22 410 58 1100 13 56 34 750 75 1600 28 510 18 280 280 1oOOO 200 7000 43 1100 91 1000 210 4600 100 3200 - 1100 - 340 1400 38000 6 48 84 1500 51 510 26 280 1 200 170 130 4 700 2 700 400 840 2 800 1600 530 180 18 ooo 14 40 40 340 48 210 29 110 220 150 150 61 0 690 140 170 550 150 120 77 3 900 S13 S14 S15 S16 S17 S18 S19 S20 S21 S22 110 9 880 40 630 94 1800 1900 320 160 1300 560 560 35 890 400 340 1300 270 160 370 130 3000 6000 2600 3500 260 400 480 790 460 2800 800 1800 2400 530 110 170 18000 21000 13 26 60 670 37 290 14 160 300 120 182 1110 870 130 140 460 230 110 38 4 900 17 27 41 10 54 1400 710 53 99 2600 1700 220 820 40000 13000 1900 130 2900 1900 310 130 11000 7300 1300 24 8900 620 650 180 970 3400 510 300 14000 8500 1200 120 1400 1600 380 53 820 880 82 1700 46000 16000 3300 1200 44000 14000 2600 130 1500 2400 400 360 6400 7600 530 630 10000 15000 670 86 23000 17000 1900 42 800 1300 330 6100 216000 115000 16000 10 610 1800 - 10 4.5 90 1500 170 600 25 290 960 150 110 5 200 3 200 340 910 2 200 1 800 450 160 18 OOO 12 13 110 25 110 52 860 740 180 54 120 360 32 17 65 210 110 330 26 72 11 76 480 840 390 810 31 150 210 170 250 580 88 260 - 110 22 65 3 100 4900 s11 s12 7 11 21 20 31 54 540 360 43 49 240 230 14 24 130 110 210 200 90 76 58 76 690 650 610 490 95 81 130 150 370 400 220 110 64 12 110 30 3700 3200 S23 S24 21 17 29 47 73 67 550 1400 73 67 250 360 9 4 140 540 360 390 110 160 150 43 790 1600 580 1300 130 260 130 160 400 450 160 670 27 28 4000 7600 24 - * For full names, see text.+ Dashes indicate below detection limit.Analyst, February 1995, Vol. 120 247 seasonal variations of PAH concentrations. Obviously, the concentrations reveal a trend: concentrations appear to be distinctly higher in winter than in summer, which could be explained by increased coal and oil combustion. Although there are no reports on the seasonal variations of PAH levels in street dust, the results here may be discussed with reference to some results on airborne particles.In Japan,s it was reported that PAHs in airborne particles were related to meteorological factors. Often, the concentrations of PAHs during night-time were higher than those during daytime, both in summer and in winter, and markedly higher concentrations were observed in winter when a surface inversion layer appeared. As another reason for a winter maximum of some PAHs in airborne dust, the use of studded tyres6 has been reported. l o t C D n I I 6/90 6/90 10190 12/90 2/91 419 1 619 1 Date Fig. 3 Seasonal variation of the PAH concentration of street dust from four different sampling sites. A , Mainz railway station; B, Mainz-Mombach; C, on highway A60; and D, under highway A60. 0, 0, 5 1000 800 600 400 200 0 The trend observed in this study is inconclusive as there are only very few data that show the discussed trend, and which also might be due to unknown singular and local effects.Abundance Distributions of PAHs It has already been mentioned that the concentrations of fluoranthene, pyrene and phenanthrene are much higher than those of all other PAHs in all the investigated dust samples. Fig. 4 shows the distributions of 15 PAHs in the four samples: S13 (Frankfurt airport parking), S17 (Mainz-Mombach indus- trial area), S22 (on the A60 highway) and S7 (from a small town). Basically, all PAH distributions in street dust samples have the same pattern with one interesting peculiarity: the relative amount of chrysene compared with the other dominant PAHs is distinctly smaller in the airport parking (S13) and in the Mainz-Mombach industrial area winter samples (S17) than in the other two samples.This holds true also for the samples S5, S19 and S24. In S5, S13, S17, S19 and S24 the chrysene: fluoranthene ratio is 0.07, 0.15, 0.22, 0.20 and 0.28, respec- tively, whereas it is between about 0.5 and 0.8 for the other samples investigated. However, the summer and autumn samples from the Mainz-Mombach sampling site (S9, S14 and S20) do not show such a low chrysene : fluoranthene ratio as does the winter sample S17 from this site. With reference to Table 1, one might speculate that the relative chrysene ratio is small at relatively dark and closed sampling sites, and is smaller in winter than in summer, independent of the absolute concentrations.The PAH distribution in street dust may be compared with distributions of PAHs in other relevant samples. The PAHs emitted from brown coal-fired residential stoves were ana- lysed by Grimmer et al. 16 and their abundance distribution was very similar to that found in street dust in this work. Other similar PAH abundance distributions have been found in urban dust," sediments,18 tobacco smoke condensates19 and in airborne particulate matter.20 ""V I 250 1 200 Fig. 4 S22 (on the highway A60); and (d) S7 (a village). Abundance of 15 PAHs in four street dust samples. ( u ) S13 (Frankfurt airport parking); ( h ) S17 (Mainz-Mombach industrial area): ( c )248 Analyst, February 1995, Vol. 120 A completely different type of abundance distribution was found in the gasoline station sample (S6), where the maximum distribution occurs for 2-MePh.This distribution is shown in Fig. 5, together with the respective distribution from diesel particulates.17 In contrast to the PAH distribution of the other samples, the gasoline station and diesel samples show very high relative concentrations of 2-MePh. Hence it might be concluded that the pollution in the gasoline station is a restricted local pollution caused by the emission from diesel cars. Conclusion An attempt has been made to replace non-polar solvents such as hexane by the non-toxic C 0 2 under supercritical condi- tions. It turned out that the properties of inexpensive C 0 2 are sufficient for this application. The high recoveries obtained indicate that C02 at 40 "C and 200 bar is a good substitute for non-polar organic solvents in this application.Hence extrac- tion of PAHs using supercritical C02 is considered to be a 3000 2000 loo0 n 50000 40000 30000 20000 10000 0 1' good simple, inexpensive step towards a 'cleaner' analytical laboratory. The authors are indebted to R. Nagel and T. Ternes for making available their GC-MS system. A grant to Y. Y. from the Gottlieb Daimler and Karl Benz Foundation and financial support from the Centre of Environmental Investigations of the University of Mainz are gratefully acknowledged. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 References Karcher, W., Fordham, R. J.. Dubois, J. J., Glaude, P. G. J. M., and Ligthart, J. A. M., Spectral Atlas of Polycyclic Aromatic Compounds, Including Data on Occurrence and Biological Activity, Reidel, Dordrecht, 1985. Takada, H., Onda, T., and Ogura, N., Environ. Sci. Technol., 1990,24, 1179. Takada, H., Onda, T., Harada, M., and Ogura, N., Sci. Total Environ., 1991, 107.45. Nuekomm, S., Vu Duc, T., and Barblan, C., Soz. - Praeventiv- med., 1975, 20, 65. Kobayashi, S., and Nishikawa, M., Nagasaki-ken Eisei Kogai Kenkyushoho, 1983,25, 11. Tamakawa, K., Matsumoto, K., Mishima, Y., Seki, T., and Tsunoda, A., Sendai-shi Eisei Shikenshoho. 1986,16,305. Hawthorne, S . B., Anal. Chem., 1990,62, 633A. Hawthorne, S. B., and Miller, D. J., Anal. Chem., 1987, 59, 1705. Hawthorne, S. B., and Miller, D. J.. J. Chromatogr., 1987,403, 63. Hawthorne, S. B., and Miller, D. J., J . Chromatogr. Sci., 1986, 24,258. Wright, B. W., Wright, C. W., Gale, R. W., and Smith, R. D., Anal. Chem., 1987,59, 38. Lohleit, M., Hillmann, R., and Bachmann, K., Fresenius' 2. Anal. Chem., 1991,339, 470. Unger, K. K., and Roumeliotis. P., J. Chromatogr., 1983,282, 519. Sugiyama, K., Saito, M., Hondo, T., and Senda, M., 2. Chromatogr., 1985, 332, 107. Schafer, K., and Baumann, W., Fresenius' 2. Anal. Chem., 1989,332, 884. Grimmer, G., Jacob, J., Naujack, K.-W., and Dettbarn, G., Anal. Chem., 1983, 55,892. Niles, R., and Tan, Y. L., Anal. Chim. Acta, 1989, 221, 53. Giger, W., and Blumer, M., Anal. Chem., 1974, 46, 1663. Lee, M. L., Novotny, M., and Bartle, K. D., Anal. Chem., 1976,48,405. Greaves, R. C., Barkley, R. M., and Sievers, R. E., Anal. Chem., 1985,57,2807. Paper 4103300 K Received June 3, 1994 Accepted July 18, I994 Fig. 5 PAH distribution in (a) a sample from a gasoline station (S6); and (b) in diesel particulates (from ref. 17).

ISSN:0003-2654    

DOI:10.1039/AN9952000243

出版商:RSC    

年代:1995

数据来源: RSC