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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The Hexyl(2,4,6,2′,4′,6′-hexanitrodiphenylamine) anion forms ion-pairs with alkali metal cations to some extent in an aqueous solution. The association constants of these ion-pairs were determined both in nitrobenzene by conductivity measurements and in water by the solvent extraction method. The association constants in nitrobenzene (KoMR) decrease in the following order: Li>Na>K>Rb>Cs. The plot of log KoMR against the ionic potential of the alkali metal ions was found to be linear. In nitrobenzene saturated with water, however, the constants vary from 2 to 4. In water the asscoiation constants (KaMr) vary from about 10 to 400, and the value increases as follows: Li<Na<K<Rb (<Cs). A plot of log KaMR against the reciprocal of the effective diameter of the hydrated alkali metal ions was found to be linear.

The distribution of alkali metal picrate complexes of macrocyclic polyether (dibenzo-18-crown-6) between water and benzene was investigated. The polyether-cation complexes were found to be of a 1:1 stoichiometry. The formation of 2:1 complexes was recognized for Rb and Cs in a large excess of the poiyether. The extractability of complex cation-picrate ion-pairs decreases in this sequence: K>Rb>Cs>Na>Li. The values of the extraction constants (logKex) were determined to be 4.65, 3.75, and 3.07 for K, Rb, and Cs compounds respectively. The thermodynamic quantities for the extraction process were calculated from the change in the extraction constants with the temperature. The extraction reactions are all exothermic, accompanied by an entropy decrease.