摘要:

A sensitive method for the spectrophotometric determination of osmium at the ppb level is described. The method is based on the formation of a brown-coloured complex by heating the reaction mixture containing Os(VIII), pyrocatechol and a hydroxyamidine at pH 8.5 over a boiling water bath, with subsequent extraction of the coloured species into chloroform. The molar absorptivity of the coloured species with N-hydroxy-N,N′-diphenylbenzamidine is 3.95 × 1061 mol−1cm−1at λmax= 410 nm. The method is free from interferences for almost all ions tested.

ISSN:0306-7319    

DOI:10.1080/03067319208027395

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An enzymatic method was developed for the determination of ammonia concentrations in lake water. Lake water samples containing ammonia were mixed with a glutamate dehydrogenase (GIDH), reduced nicotinamide adenine dinucleotide phosphate (NADPH) and 2-oxoglutarate. The decrease in the absorbance intensity caused by the disappearance of NADPH by this reaction was measured at 340 nm. There was a linear relationship (r= 0.9997) between peak height and ammonia concentration over the range 0–29 μM. The detection limit was 0.29 μM for a sample volume of 250 μl. Interference of amino acids and urea at concentrations of 50 mg l−1was negligible. Good agreement was found between the enzymatic method and indophenol blue colorimetry.

ISSN:0306-7319    

DOI:10.1080/03067319208027396

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A wide variety of agricultural soils from different regions of India such as paddy, wheat, mustard, potato, cotton, tea, tomato, sugarcane, grape and urban soils were surveyed for the residual levels of persistent organochlorine insecticide residues in 1988 and 1989. DDT and HCH concentrations were found to be higher in upland soils and lower in paddy field soils. These results indicate the large application of HCH and DDT compounds for agricultural purposes in India. In urban soil DDT levels were higher than HCHs reflecting the use of the former insecticide in relatively large amounts for vector control. Among DDT compounds,p,p′-DDE showed higher percentage in paddy and upland soils. On the other hand,p,p′-DDT contributed to higher levels in urban soils. The β-HCH was detected as the dominant isomer in both agricultural and non agricultural soils. The levels and percentage compositions of DDTs and HCHs revealed the extent of environmental contamination caused by the continuous usage of persistent organochlorine insecticides in large quantities in tropical areas like India.

ISSN:0306-7319    

DOI:10.1080/03067319208027397

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A minimum acceptable volume of blood for the simultaneous determination of the lipid and chlorinated hydrocarbon content was established at 50 ml. At that volume the coefficients of variation for lipid and chlorinated hydrocarbon residue determinations were > 10 and 20% respectively. Comparing chlorinated hydrocarbon levels in whole blood with serum and plasma from the same blood pool, indicated that approximately 25% of the tri-to penta chlorobiphenyls were found in the serum and 40% in the plasma. In contrast, 55–83% of the hexa-to octachlorobiphenyls were found in the serum and plasma. From among the organochlorine pesticides, between 80–110% of the trans-nonachlor and DDTs appeared in the serum and plasma, but for others this range was considerably lower (40–71%). In general no appreciable differences were observed in the recoveries of some chlorinated hydrocarbons from fortified blood and serum.

ISSN:0306-7319    

DOI:10.1080/03067319208027398

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The present study has shown that cyanopropyl- (CN) bonded silica may be applicable for the fractionation by high pressure liquid chromatography (HPLC) of mass and mutagenic activity of organic extracts from some incinerator emissions. Dichloromethane-extractable organics from particles emitted by two different municipal waste incinerators and by a pilot-scale rotary kiln incinerator that was combusting polyethylene plastic were fractionated by HPLC, and the mutagenicity of the collected fractions was determined by means of a microsuspension mutagenicity assay with Salmonella TA98. The CN-bonded silica column provided high (80–100%) mass and mutagenicity recoveries for most emission extracts, and it fractionated the mutagenic activity. The results suggest that the emissions from municipal waste incinerators contain a high amount of direct-acting (-S9) mutagenic activity that is resolvable by HPLC using CN-bonded silica. Sub-fractionation of selected mutagenic HPLC fractions and subsequent analysis by gas chromatography-mass spectroscopy can be used to identify mutagenic species within complex incinerator emissions. The coupling of microsuspension bioassays to HPLC fractionation should be a useful tool for this type of analysis.

ISSN:0306-7319    

DOI:10.1080/03067319208027399

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A differential pulse polarographic method has been developed for the simultaneous low level determination of nickel and cobalt in the presence of furildioxime in natural waters. The nature of the electrode processes was studied with cyclic voltammetry. Limits of determination of 0.4 μg/L and 0.15 μg/L were achieved for nickel and cobalt respectively

ISSN:0306-7319    

DOI:10.1080/03067319208027400

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Tissue and blood samples were collected from muskoxen harvested in 1989 on Victoria Island, Northwest Territories. Liver and kidney were tested for trace elements and toxic metals, and fat and serum were tested for residues of organochlorine pesticides. Copper, manganese, and zinc levels were in the range considered adequate for sheep and cattle. Selenium levels in the muskoxen (liver mean value, 0.10 μg g−1, kidney mean value, 0.36 μg g−1) would be considered deficient in sheep and cattle. No elevated levels of toxic metals (arsenic, cadmium, lead, mercury) were found. All fat samples tested contained hexachlorobenzene (mean value, 45.4 ng g−1) and 97% of the fat samples contained trace levels of α-hexachlorocyclohexane (mean value, 5.1 ng g−1). Twelve percent of the serum samples contained hexachlorobenzene (mean value, 2.8 ng g−1). Hexachlorobenzene levels in the fat of some unweaned calves exceeded tolerance levels set in Canada for food animals.

ISSN:0306-7319    

DOI:10.1080/03067319208027401

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Procedures are presented for qualitative screening and subsequent quantitation of residues of explosives and related compounds found at sites contaminated by open burning/open detonation (OB/OD) disposal of munitions. Methods are reported for recovery of explosives and polycyclic aromatic hydrocarbons (PAHs) from soil via sonic extraction into acetonitrile; and explosives from water via trapping onto C18 disposable cartridges. Complimentary HPLC procedures were used for identification and quantification of these compounds. A qualitative HPLC gradient method was developed, and used to screen samples for a wide range of explosives and PAHs. Quantitation of explosives and their environmental reduction products was accomplished using HPLC isocratic methods. Recoveries of explosives and degradation products doped into sandy loam soil were greater than 90%. Corresponding recoveries from aqueous samples were comparable for the nitroaromatics, but were poorer for the nitramines. Criteria of detection for individual munition residues ranged from 0.067 mg 1−1to 0.37 mg 1−1.

ISSN:0306-7319    

DOI:10.1080/03067319208027402

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The influence of sample acidification on the speciation of iron in aqueous solutions has been investigated. When hydrochloric acid is used, iron(II) is transformed into several moieties, believed to be chloro-complexes, whose chromatographic properties are quite different from those of the parent iron(II) species. This process is favored by high (>0.5 M) HCl concentrations.

ISSN:0306-7319    

DOI:10.1080/03067319208027403

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In mud waste and slag waste produced during the extraction of tin by different processes 25 trace metals have been determined by atomic absorption and optical emission spectroscopy. The usefulness of tin wastes for the recovery of Nb and Ta is indicated.

ISSN:0306-7319    

DOI:10.1080/03067319208027404

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor