摘要:

A method is reported for the simultaneous determination of phosphate and silicate by flow injection analysis based on the different rate of formation of the heteromolybdic acids of the two anions. Measurements are based on the colour of the ion-pairs formed between the said molybdic acids and Rhodamine B. The method allows the determination of the two anions at a rate of 20 samples/h over the ranges 0.05–2.5 ppm (phosphate) and 0.8–15 ppm (silicate), which allows application to a variety of waters.

ISSN:0306-7319    

DOI:10.1080/03067319108026967

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Fluorescent probes, especially a newly synthesized N-substituted 1-cyanobenz[f]-isoindole quaternary ammonium fluorophore, were used as counter ions in a reaction detector for on-line ion-pair extraction of phenoxyacid herbicides. The probe was used in an on-line post-column set-up coupled to a reversed-phase chromatographic system. After separation on an C-8-bonded silica column using an aqueous methanol (pH 2.5) mobile phase, the herbicides were on-line deprotonated by post-column addition of a 10mM sodium phosphate buffer (pH 8.0), in which the probe was dissolved. Subsequently, the ion-pairs were extracted on-line with chloroform-1-butanol (80:20, v/v) and were monitored by fluorescence detection. Using this system, at least seven herbicides could be separated. The detection limits of 2,4-dichlorophe xyacetic acid and 2,4,5-trichlorophenoxyacetic acid were 400 pg (S/N = 3). The repeatability, based on peak height measurements, for 100ng injections was about 0.5%. Calibration curves were linear over the investigated range of 1–100ng, with correlation coefficients of 0.999 for the two analytes. Application to a drinking water sample is presented.

ISSN:0306-7319    

DOI:10.1080/03067319108026968

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A suitable indirect spectrophotometric method for the determination of sulphide in water, based on the reduction of 1,2-naphthoquinone-4-sulphonate (NS) has been developed. The excess of NS is spectrophotometrically determined based on the red colour produced in its reaction with sulphanilic acid at pH 4.0–6.5. Maximum colour intensity is obtained after 40 min and the apparent molar absorptivity at 470mm is 3.5×103I.mol−1.cm−1. The sulphide concentrations can be calculated by the difference in absorption of blanks and samples.

ISSN:0306-7319    

DOI:10.1080/03067319108026969

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The concentration efficiency of synthetic macroreticular resins, XAD-2 and XAD-7 and carbonaceous resins, XE-340, XE-347 and XE-348 was evaluated and compared using trace levels of eight radioactive model environmental contaminants present in aqueous medium. Influences of chemical functionalities of the solvents, physical characteristics of the sorbents, and pH of the aqueous medium on sorption of the model compounds were investigated under frontal dynamic chromatographic conditions. The elution behavior of these sorbates and desorption properties of the polymer adsorbents with respect to solvents of different polarities were studied.

ISSN:0306-7319    

DOI:10.1080/03067319108026970

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The objectives of this study were to identify, classify and categorize polychlorinated biphenyl (PCB) residues in samples collected from the Hamilton and Wheatley Harbour environmental compartments. The study is built around the use of a principal components analysis method, namely the soft independent modelling of class analogy (SIMCA) technique. This multivariate method is widely used for evaluating differences and observing similarities among multiple objects. The results obtained from this work confirm that the gas chromatographic data sets obtained with the samples provide a good approximation of the pattern derived from a determination of the composition of commercial Aroclors in water, sediment and biota samples. The data analysis technique provides insight into the origin of PCB contamination in environmental samples and indicates pathways for the environmental degradation or bioaccumulation of PCBs. This investigation contributes some evidence that multivariate reduction techniques are suitable for the investigation of complex data sets in environmental studies.

ISSN:0306-7319    

DOI:10.1080/03067319108026971

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The work described in this paper shows how we have investigated the utility of polar polyimide sorbents for the collection of polar and non-polar volatile organic compounds in ambient air. The results indicate that supercritical carbon dioxide can be used to recover a variety of compounds with a wide range of volatilities from polyimide sorbents and that these compounds can be effectively collected onto an adsorbent micro-trap after the expansion of the fluid prior to thermal desorption gas chromatographic analysis. Molecular sieve 3A was used and found to have a very high capacity for removal of water from the supercritical fluid extract stream. The sieve tended to adsorb polar compounds in the absence of water; the presence of water sometimes reduced analyte adsorption. The method was used to collect, recover, and analyze volatile organic compounds from the air of a laboratory building and was shown to be quite sensitive for appropriate compounds.

ISSN:0306-7319    

DOI:10.1080/03067319108026972

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

An analytical procedure utilizing solid phase extraction with octadecylsilane bonded to silica (C18) cartridges combined with gas chromatography/mass spectrometry (GC/MS) was developed to analyze semi-volatile chlorinated acids found in drinking water. A system has been designed which will enable the analysis of this class of compounds with minimum sample manipulation and detection limits in the low ng/L range. The overall accuracy and precision were comparable to other methods used for compliance purposes. Among the advantages of the developed methodology are its applicability for field sampling and at the same time, provides a simple and inexpensive mean for sample preservation.

ISSN:0306-7319    

DOI:10.1080/03067319108026973

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Urinary PAH-metabolite excretion by non-exposed volunteers, temporarily living on a PAH-poor and PAH-rich diet, respectively, as well as by occupationally PAH-exposed coke plant workers and road workers has been studied. Significant differences in the amount of the metabolites excreted in the urine were detected; the ratio of various metabolites was also found to be different. The mass excretion per liter of the metabolites from phenanthrene was found to be for the unexposed volunteers about 3.5μg/1, for coke plant workers about 70μg/l and for road workers about 35 μg/l. For the metabolites of chrysene the values were 0.03 μg/1 2.5 μg/l and 0.09μg/l, respectively, and for the total metabolites of benzo(a)pyrene: 0.006μg/l for unexposed persons, 0.37 μg/l for coke plant workers and 0.019 μg/l for road workers.

ISSN:0306-7319    

DOI:10.1080/03067319108026974

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A new method for the determination of 1,5-bis(2,4-dimethylphenyl)-3-methyl-1,3,5-triazopenta-1,4-diene (Amitraz) in honey by derivative spectrophotometry is proposed. Amitraz is extracted from aqueous honey solutions with CCI4and it is determined between 0.1 and 1.5 μg. ml−1from the first-derivative spectrum by measuring the peak amplitude at 332 nm (1D332), as the vertical distance from the peak to the baseline.

ISSN:0306-7319    

DOI:10.1080/03067319108026975

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

TROUBLESHOOTING IN DER HPLC (Fehlersuche in der HPLC) by N. Vonk, B. G. J. Baars and H. Schaller, Birkhauser Verlag, Therwill (Switzerland), 140 pages, ISBN 3-7643-2400-7, SFr 44.80.

ISSN:0306-7319    

DOI:10.1080/03067319108026976

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor