Procedures for Trace Analysis of Dissolved Inorganic and Organic Constituents in Water

A study of different solvent systems for the atomic absorption determination of cobalt revealed that acetone results in best sensitivity. Acetone is the solvent of choice for the sensitive measurement of several metals. Hence, methods were investigated for the separation of acetone from water by salting out so that possible solvent extraction of metal chelates into this solvent could be performed. About two-thirds saturated calcium chloride proved to be the best system for salting out of the acetone. It is essentially a neutral salt and is in general a weakly complexing salt, resulting in minimum interference in solvent extractions. Solvent extraction of several elements as dithizone or APDC chelates into acetone was successful. A new anodic stripping voltammetric method was developed for stability studies of the poorly characterized APDC chelates. The method allows the study of highly insoluble chelates. Over sixty elements were successfully measured by flame emission spectroscopy using the nitrous oxide-acetylene flame. Optimum instrumental and flame parameters and detection limits for each element were determined. High concentrations of neutral salts have, been shown to enhance titration curve breaks of weak bases titrated in either aqueous or nonaqueous solutions. This allowed the coulometric titration of microequivalent quantities of bases with Kb values as small as 4 x 10-12. Volumetric titration of bases with Kb values of 10-14 was possible in nonaqueous solvents