摘要:

A volumetric method for the determination of malathion in emulsifiable concentrates has been developed. The method is based on the alkali cleavage of malathion to give O,O-dimethylphosphorodithioic acid that forms a complex with Bi(III). The complex is extracted with chloroform and the bismuth left uncomplexed is titrated with the disodium salt of ethylenediaminetetraacetic acid. The free O,O-dimethylphosphorodithioic acid that may be present and interfere in the determination is rectified by doing the complex formation without hydrolysing the sample. Hence, the amount of malathion in the sample can be determined.

ISSN:0003-2719    

DOI:10.1080/00032718508066201

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Measurements of airborne concentrations of (monomeric) 2,4- and 2,6-toluene diisocyanate (2,4- and 2,6- TDI), 4,4′ - diisocyanato diphenylmethane (MDI) and phthalic anhydride have been performed at 17 Danish manufactories using these compounds in the production of polyurethane foams, insulating materials, elastomers, coatings, lacquers and glues.

ISSN:0003-2719    

DOI:10.1080/00032718508066202

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Two flow injection analysis catalytic-fluorimetric methods for the determination of titanium are suggested, based on the measurement of the peak height and of the peak width, respectively. Both methods allow the determination of titanium at the ng.mL−1level with good selectivity. A comparison between both method is also established.

ISSN:0003-2719    

DOI:10.1080/00032718508066203

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A simple and sensitive color reaction of common epoxides as well as other some alkylating agents with 4-acetylpyrldine 2-benzothiazolylhydrazone (ABH) is described. These compounds gave a purpllsh red color after reaction with ABH for 2 hrs at 110°C in methyl cellosolve or for 20 min at 120°C followed by treatment with plperazlne on silica gel thin-layer plates. Four aliphatic terminal epoxides could be determined spectrophotometrically in the range from 20 to 125 nmol/ml. The limits of detection of these epoxides on silica gel thin-layer plates were 10 pmol/spot order by the visual inspection. The reaction mechanism is also discussed based on the chemical structure of the isolated chromophore.

ISSN:0003-2719    

DOI:10.1080/00032718508066204

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A method is presented for the determination of manganese in mouse brains by furnace atomic absorption with Zeeman background correction. Precision for the method of standard additions is compared with that of aqueous calibration curves. NBS bovine liver SRM is analyzed to verify the accuracy of the method.

ISSN:0003-2719    

DOI:10.1080/00032718508066205

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Since the charring temperature of As in environmental samples can be raised to 1320°C with Pt, the sensitivity of determining As by ET-AAS is increased about 50% using Ni salt as a matrix modifier. The interference of most foreign ions is avoided, but PO˭and SO≡cause a depression and F−and SiO˭produce an enhancement of the As absorption. The method has been applied to pollution control and river sediment samples with satisfactory results.

ISSN:0003-2719    

DOI:10.1080/00032718508066206

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

An improved and sensitive photometric determination of cobalt based on the formation of a coloured chelate with photochemically generated anti-2-thiophenaldehyde 2-pyridylhydrazone (anti-TAPH) is described. The calibration graph is linear over the range 0.017–0.8 μg/ml. A detection limit of 4 ng/ml and r.s.d. of 0.76% was found. Colour development is instantaneous and remains stable for at least 4 hours. The corrected stoichiometry of the chelate was found to be 3:1 (L:M) when the syn-anti ratio at the photostationary state was considered. The influence of reaction variables and the effect of foreign ions are also discussed.

ISSN:0003-2719    

DOI:10.1080/00032718508066207

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Results on an impaction-electrothermal atomization atomic absorption spectrometric system for the direct, and on a nearly real-time basis, determination of cadmium, copper, and manganese in the laboratory atmosphere are presented. Background levels for cadmium were 3 ng m−3, for copper were 100 ng m−3, and for manganese were 30 ng m−3and were found to increase with activity in the vicinity of the system. Addition of a connecting faceplate to the impactor allowed a more convenient and accurate method of standardization to be achieved.

ISSN:0003-2719    

DOI:10.1080/00032718508066208

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Nitrite is determined by its reaction with a measured but excessive amount of pyridine-4-carboxylic acid hydrazide in acid medium (when the two substances react in a 1:1 molar ratio) and evaluation of the surplus hydrazide by titration with chloramine-T in the presence of acidified potassium bromide, the end-point being shown by the decolorization of the methyl red indicator. Nitrate, copper(II), mercury(II), etc. are found not to interfere, and the determination of nitrite in the presence of diazotized aromatic amines is demonstrated.

ISSN:0003-2719    

DOI:10.1080/00032718508066209

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The calcium titration experiments were performed with 9 uM and 100 uM concentrations of Arsenazo III (Az) at various pH°s in the presence as well as in the absence of ethylene glycol-bis-(2-amino ethylether)-N,N°-tetra-acetic acid (EGTA). Analysis of results indicated that in the presence of EGTA in 9 uM Az solutions the Ca-Az stoichiometry changes from 1:1 to two Ca binding with one Az (2:1) upon increase in pH from 6.55 to 7.26. In the same systems but without EGTA the binding stoichiometry remains 1:1 throughout the pH range 6.55 to 7.32. In case of 100 uM Az III, however, EGTA has no effect on Ca-Az stoichiometry and it is 1:1 in the above pH range. An estimate of dissociation constants (KD) in EGTA containing systems showed a simultaneous decrease in KDby three orders of magnitude with a change in stoichiometry from 1:1 to 2:1 in the case of 9 uM Az III. At 100 uM dye concentration, with no change in 1:1 binding stoichiometry, KDalso remained constant throughout the pH range studied. We suggest that at lower dye concentration a competition between Ca-Az and Ca-EGTA binding causes this change in stoichiometry. The discrepancy among the previous reports about Ca-Az stoichiometry appeared to be due to change in pH in the presence of EGTA.

ISSN:0003-2719    

DOI:10.1080/00032718508066210

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor