摘要:

A rapid screening method for the determination of carbaryl and propoxur using p-nitroaniline is described. Carbaryl and propoxur are determined spectrophotometrically: carbaryl forms a stable blue coloured species with diazotized p-nitroaniline in a fairly alkaline medium while propoxur forms a purple coloured species with the same reagent under similar conditions. The blue and purple coloured species are extracted into 3-methyl-1-butanol showing absorbance maxima at 605 and 540 nm, respectively. The relationship between absorbance and concentration is linear in the range of 0.12 - 0.96 ppm and 0.19–1.5 ppm, respectively for carbaryl and propoxur. The method can successfully be applied for the determination of carbaryl and propoxur to levels as low as 0.04 and 0.06 and 0.12 and 0.19 ppm in water and grain samples, respectively.

ISSN:0306-7319    

DOI:10.1080/03067319208027562

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Analysis of three oxygenated solvents (acetone, THF and 1,4-dioxane) in groundwater was conducted by dynamic thermal stripping followed by thermal desorption into a GC-MSD with monitoring of selected ions. This method has a significantly better practical quantitation limit than the current EPA method (13 vs. 150 μg/L for 1,4-dioxane). Using this method a plume of groundwater contaminated with 1,4-dioxane emanating from a former solvent disposal site was mapped. More than 10 years after disposal, concentrations of 1,4-dioxane greater than 3 mg/L were measured at points more than 300 m from the site.

ISSN:0306-7319    

DOI:10.1080/03067319208027563

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Phosphorus was determined in samples of glass from laboratory glassware, using a hydrofluoric digestion followed by colorimetry. Glass from such sources is shown to contain up to 0.002% of phosphorus. Experiments on storage of samples in glass bottles show that glassware may contribute significant phosphorus contamination to natural water samples, particularly seawater, as a result of partial dissolution of glass into the sample during storage. The release of phosphate from glassware into the sample is greater than the concentration expected from the P/Si ratio in glass and the silicate dissolution in the sample. This is attributed to the formation of a leached layer at the surface of the glass in contact with the water. Under the alkaline digestion conditions applied in this work for the total phosphorus determination, the dissolution of glass does not appear to be a source of measurable phosphate contamination. Nevertheless each analyst must satisfy himself that no phosphate contamination occurs under his particular working conditions with his own glassware.

ISSN:0306-7319    

DOI:10.1080/03067319208027564

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A thorough investigation on the denuder method for ambient NO2determination, based on the reaction with phenoxide ions has been made. A thermostatted sampling unit comprising an annular denuder coated with alkaline eugenol and a nylon pre-filter has been found to be suitable for ensuring quantitative sample collection and preventing interferences from nitrous acid as well as from gaseous and paniculate nitrate. Results of laboratory and field tests concerning the effect of humidity on collection efficiency, the oxidation of nitrite on the wall by O3/oxidants and the reliability of the method are reported and discussed.

ISSN:0306-7319    

DOI:10.1080/03067319208027565

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Infrared, solid-state13C NMR and liquid-state1H NMR spectra were recorded as a means of investigating structural components in the high-molecular part of pulp mill effluent and different stages of the chlorine bleaching process. Comparison was made with the spectra of kraft lignin, native lignin, and humic substances. The1H and13C spectra of mill sample fractions showed that there are no marked differences in the structure of high-molecular-weight fractions before and after the purification plant. However, comparison of the13C spectra of mill samples with the spectra of native and kraft lignin showed that lignin undergoes a pronounced change in the bleaching process. The13C NMR spectrum of the purification plant outflow sample closely resembled the spectra of the humic reference materials. The most significant difference in the infrared spectra of the chlorolignin fractions and reference humic materials was the presence of strong C—CI absorption bands in the chlorolignin spectra and their absence from the spectra of humic samples.

ISSN:0306-7319    

DOI:10.1080/03067319208027566

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Microcystins as cyanobacterial (blue-green algal) toxins are found from toxic waterblooms in freshwater lakes and reservoirs for drinking water all over the world.

ISSN:0306-7319    

DOI:10.1080/03067319208027567

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The potential of infrared spectroscopy for detection and speciation of cyanides in aqueous solution has been assessed. The non-invasive technique has good prospects for speciation of many metal cyanides and other cyaniferous ions, and sensitivities of 10-100 mg 1−1can be achieved readily. An additional species, thought to be an aquo- or hydroxo-cyano complex, was observed to be present in association with ferricyanide ion in strongly alkaline solutions.

ISSN:0306-7319    

DOI:10.1080/03067319208027568

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A pulse dilution system in which small volumes of gas are injected into an air flow, by means of a standard 6-port G. C. valve, is described. This system is shown to produce the expected dilution, and to be able to produce gas mixtures whose concentrations can be varied by an order of magnitude simply by varying the injection frequency.

ISSN:0306-7319    

DOI:10.1080/03067319208027569

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0306-7319    

DOI:10.1080/03067319208027561

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor