On the basis of the coloration formed with molybdate and malachite green in aqueous solution, tracc amounts of phosphate were determined. The molar absorptivity was 7.8 x lo4 1 mol-l cm-1 at 650 nm. The absorbance of the reagent blank was about 0.02, and its relative standard deviation was less than 10%. The recommended concentration range of phosphorus was 0.1-5 pg and the limit of detection was 0.01 pg of phosphorus. The sample solution was acidified with sulphuric acid and heated in a water-bath above 90 "C for 40 min, and subsequently i t was coloured with niolybdate and malachite green.The method was applied to the determination of parts per billion ( lo9) amounts of phosphorus in river and tap waters; the relative standard deviation was less than 4% and the recovery was 95-101 "/o.The colour was stabilised by adding poly(viny1 alcohol).

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Several cationic dyes were evaluated as reagents for the spectrophotometrlc determination of anionic surfactants. Of the dyes examined, ethyl violet was the most useful reagent. By use of this dye, trace amounts of anionic surfactants could be extracted Into benzene and toluene In a single extraction and determined spectrophotometrlcally at 615 nm; the molar absorptivity was about 1 X 10s L mol-1 cm-1 and the absorbance of the reagent blank was 0.01. The method could be applied to the determination of parts-per-bllllon amounts of anionic surfactants In waters with satisfactory results.

Alkali and alkaline earth metal salts of 2,2′,4,4′,6,6′-hexanitrodiphenylamine (HND) were extracted into nitrobenzene in the absence or presence of several crown ethers or cryptands which differ from one another in hole size. The quantity of water transferred to the nitrobenzene phase was determined by means of the Karl-Fischer method. The NMR and near-infrared spectra show that the coextraction of water is caused by the hydration of the cations. The number of water molecules attached to the cations increases upon going from Cs+ (0.6) to Li+ (5.6) and from Ba2+ (10.5) to Ca2+ (13.0). The complexation between these cations and the crown ethers causes a clear decrease in the hydration number; e.g., in the 1:1 metal–crown ether complexes, more than half of the water molecules are removed, and in the 1:1 metal–cryptand complexes, less than one water molecule remains unremoved. The complexes of a 1:2 stoichiometry are also found; some are stable and carry virtually no water molecules. The number and type of donor atoms have no significant effect on the coextraction of water. The presence of fused benzo rings on the crown ether also has no influence on the number of water molecules.

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