ISSN:0935-6304    

DOI:10.1002/jhrc.1240180602

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractIn the present contribution, the performance of a number of commercially available selective and universal detectors that can be used in the analysis of sulfur components in natural gas is evaluated in terms of sensitivity, selectivity, reproducibility, quenching effect, stability, and compound dependence of the sulfur response. Investigated detectors include the sulfur chemiluminescnce, the flame photometric, the electron capture, the mass spectrometric, the thermal conductivity, and the flame ionization detector. The sulfur chemiluminescence detector was found to have the best overall performance,e.g., low picogram amounts of sulfur can be detected accurately and the linear dynamic range is more than five orders of magnitude. After careful optimization, the sulfur response of this detector was found to be almost compound independent. All other detectors, including the flame photometric and the electron capture detector, have more or less compound dependent responses.

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180603

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractWindow diagrams that optimize for the separation of only one or a few components in a complex mixture are applied to on‐line process analysis when speed of analysis is more important than a complete separation of all components in the sample. A window diagram based on retention indexes is the most useful for quickly evaluating the feasibility of a given pair of phases. The one with the most useful output is one based on partition ratios, as this can be used directly with the columns in hand. A PC‐based spreadsheet program with integral specific retention volume data for the common liquid phases is described as a tool for selecting the optimum ratio of lengths for the columns in h

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180604

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractEnantiomeric separation of some basic compounds, namely selegiline, amphetamine, and clenbuterol, was studied by capillary electrophoresis using an uncharged β‐cyclodextrin polymer added to the background electrolyte at pH 2.5. Both complexation and resolution were influenced by the concentration of the chiral polymer confirming our previous results obtained in our earlier work for a wide number of pharmaceutical compounds. In this further study, we examined the influence of different organic additives to the background electrolyte on the enantioselectivity of the chiral selector, also using an extended number of analytes. In most cases, the use of an organic additive resulted in a decrease of resolution. However opposite to that, in some cases,e.g.ephedrine, the organic solvent proved to be essential to achieve enantiomeric resolution. Furthermore the influence of the capillary temperature on the resolution of the analytes was evaluated. Increase of temperature had a deleterious effect on the resolution of the enantiomers. For ephedrine, however, relatively high temperature (50 °C) proved to be advantageous, for the resolution of the optical isom

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180605

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractA chiral stationary phase (CSP) derived from anthrone is quite effective for the chromatographic resolution of the enantiomers of a wide variety of compounds. Denoted CSP 4, the phase is a chiral 2,2,2‐trifluoro‐1‐(9‐anthryl)ethanol tethered to silica by an elevencarbon‐atom chain at the 10‐position of the anthryl ring. CSP 4 typically provides greater enantioselectivity than its fluoroalcohol predecessor and is synthetically much more

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180606

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractA rapid and effective procedure, developed for the determination of polar compounds in water, has been applied to hydroxycarbamates. In few minutes, it is possible to perform a catalyzed derivatization of such compounds directly in the aqueous medium, usingn‐hexyl chloroformate. Extraction withn‐hexane and injection into a benchtop GC‐MS system are the only two further steps to complete the analysis. Chemical ionization proved to be more effective than electron impact to produce valuable mass spectra in terms of selectivity and sensitivity. Linear quantitative responses were demonstrated over a two‐order‐of‐magnitude range. The minimum detectable concentration was 3 ppb for acetohydroxamic acid and 10 ppb for hydroxyurethane, obtained from Po river water samples spiked with the two hydroxycarbamat

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180607

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractOpen tubular supercritical fluid chromatography (SFC) with carben dioxide as the mobile phase has been investigated for the separation of four triterpene acids, two of which were structural isomers. These compounds, isolated fromDysoxylum pettigrewianum(Meliaceae), were chromatographed on three stationary phases with different selectivities. 30%‐biphenylmethylpolysiloxane and polyethylene glycol (Carbowax 20M) phases exhibited poor chromatographic selectivity for the compounds. The separation was improved by employing the shape selectivity of a liquid crystalline biphenylcarboxylate ester polysiloxane and utilizing simultaneous temperature and pressure programming. The elution order was explained on the basis of the molecular structures of the triterpene acids, and their interaction with the liquid crystal phas

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180608

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractTwo hyphenated techniques, gas chromatography–mass spectrometry and gas chromatography–atomic emission detection, have been used to identify the degradation products of the acaricide fluvalinate in a methanol solution of the commercially available formulation Mavrick, as well as in honey from beehives treated with this product. The major degradation products were 2‐chloro‐4‐trifluoromethylaniline (I), methyl 2‐[2‐chloro‐4‐trifluoromethylaniline]‐3‐methylbutanoate (II),N‐(2‐chloro‐4‐trifluoromethyl‐phenyl)valine (III), and 3‐phenoxybenzaldehyde (IV). Fluvalinate in honey is gradually degraded, 3‐phenoxybenzaldeh

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180609

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractVolatile compounds from biodegradable household waste and infected building materials have been studied by dynamic or equilibrium headspace sampling and concentration on Tenax TA followed by thermal desorption and HRGC‐MS. Equilibrium headspace sampling was also used to study vegetables stored for 14–18 days at ambient temperature. Over 200 compounds were tentatively identified. The concentration of organic sulfur compounds from garden waste was high enough to contribute to respiratory problems of waste handling personnel. Nitriles, alkyl nitro compounds, and alkyl nitrates were isolated from radish and carrot samples at low concentrations (10–50 ppb). Air monitoring in waste handling working environments may be required to ensure the safety of personnel. Branched aliphatic aldehydes, carboxylic acids, esters, and 2‐alkanones were found in the headspace of the infected building materials, indicating that volatile compounds may be useful for detection of microbial growth in bu

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180610

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0935-6304    

DOI:10.1002/jhrc.1240180611

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY