H.S. Rathore

Studies on chromium(III) hydroxide, arsenate, antimonate, molybdate and tungstate.

Five water-insoluble compounds of chromium(III) have been synthesized by mixing 0.10M solutions of chromic chloride and the appropriate sodium salts in the volume ratio of 1:2, at pH 6-7. Their ion-exchange characteristics have been compared. The tungstate has the highest chemical stability and the arsenate has the highest ion-exchange capacity. Chromium(III) molybdate columns have been used to separate Pb(2+) from numerous metal ions.

Thin-layer chromatographic methods for use in pesticide residue analysis

Abstract A selective review is presented, focusing mainly on stationary phases, mobile phases, detectors and TLC techniques used for the detection, separation, determination and identification of pesticide residues in various environmental samples. The results from numerous papers are presented in tabular form.

Influence of temperature on the ion-exchange properties of stannic arsenate : Separation of Pb2+, UO22+ and Cr3+ from numerous metal ions

Abstract The amorphous precipitates (stannic arsenate) obtained by mixing the 0.1 M aqueous solutions of stannic chloride and sodium arsenate in the volume ratio of 1:1 have been dried at different temperatures (40–600°). The ion-exchange properties, the solubility and the IR studies of the dried samples have been investigated. The sorption studies on the sample dried at 40° have been made in detail by raising the temperature (from 20 to 95°) of the equilibrating solution and its columns have been used for the separation of Pb2+, UO23+ and Cr3+ from numerous metal ions.

Thin-layer chromatographic behaviour of carbamate pesticides and related compounds

Abstract The thin-layer chromatographic behaviour of carbaryl, carbendazim (Bavistin), carbofuran, propoxur, phenol, 4-chlorophenol, o -nitrophenol, α-naphthol and β-naphthol was examined on alumina, barium sulphate, calcium carbonate, calcium phosphate, calcium sulphate, cellulose and silica gel G in solvents such as acetone, benzene, carbon tetrachloride, chloroform, ethanol and distilled water. The important separations achieved were carbendazim from carbaryl, propoxur, 4-chlorophenol, o -nitrophenol, α-naphthol and β-naphthol; carbaryl, propoxur, α-naphthol and β-naphthol from carbofuran, phenol, 4-chlorophenol and o -nitrophenol; and o -nitrophenol from carbofuran, phenol and 4-chlorophenol.

Detection of some nitrogen compounds and the semiquantitative determination of diphenylamine with p-dimethylaminobenzaldehyde by capillary solid-state spot-tests.

Capillary solid-state spot-tests for nitrogen compounds by reaction with p-dimethylamino-benzaldehyde are described. The tests are neither specific nor universally applicable for nitrogen compounds.

Selective detection of carboxylic acids, ureas and phenols and semiquantitative determination of citric acid by capillary solid-state spot-tests

Solid-state spot-tests for the selective detection of carboxylic acids, ureas and phenols have been developed. Mixtures of p-dimethylaminobenzaldehyde with N-methylurea and of p-dimethylaminobenzaldehyde with phthalic acid are used as reagents. Based on these tests a semiquantitative determination of citric acid is also developed. These tests utilize three properties of the coloured boundary: colour, length and direction of movement. Our work on capillary solid-state spot-tests,(1) has now been extended to some further organic compounds.

A simple method for dissolution of tantalum pentoxide.

A simple and reproducible procedure has been developed for the dissolution of tantalum pentoxide. The oxide is fused with potassium nitrate and potassium carbonate in the ratio of 2:5:5. The cooled melt is dissolved in concentrated sulphuric acid. If a tartaric acid solution is desired the sulphuric acid is evaporated and the residue dissolved in 20% tartaric acid solution.

Synthesis and properties of stannic arsenate

A new amorphous monofunctional inorganic ion-exchanger showing unusual thermal stability and considerable ion-exchange capacity even at low pH has been prepared by mixing 0·05M aqueous solutions of stannic chloride and sodium arsenate in the volume ratio 3 : 2 at pH ca. 1. This substance has Sn : As ratio of 1·84. Its ion-exchange properties have been studied and its utility has been demonstrated by quantitative separations of Cu2+ from Pb2+, Cu2+ from Fe3+, Fe2+ from Pb2+, Fe2+ from Cu2+, and Fe2+ from Fe3+.

Synthesis and ion-exchange properties of titanium molybdates

Fourteen samples of titanium molybdates have been prepared under a range of conditions. They are all amorphous monofunctional cation exchangers with an ion-exchange capacity of 0·80–1·60 mequiv./g. The Ti:Mo ratios of these samples are 1 : 1, 2 : 1, or 1 : 2. The molybdate with Ti:Mo ratio of 1 : 1 has been more extensively studied and its columns have been used for the analytically difficult quantitative separations of Zn–Pb–Tl and Bi–Pb–Tl.

Chromatographic and related spot tests for the detection of water pollutants

Abstract Spot test analyses are used in the preliminary qualitative analysis of pollutants in water. In this review, recently reported spot tests are described. The limit of detection of the spot tests is at tests is at the microgram level.