A sensitive spectrophotometric method for the determination of ethylenediaminetetraacetic acid (EDTA) in foods is described. The method involves the reaction of EDTA with Fe3+ to produce the EDTA-Fe chelate, followed by the removal of excess of Fe3+ by a chelate extraction technique using chloroform and N-benzoyl-N-phenylhydroxylamine and the formation of a chromophore with 4,7-diphenyl-1,10-phenanthroline-disulfonic acid. The calibration graph was linear in the range 0.5-40.0 micrograms cm-3 of EDTA with a slope of 21.1. The relative standard deviation at 10 micrograms cm-3 of EDTA was 1.6% (n = 10). There was no interference from most of the common ingredients of commercial foods. More than 90% of EDTA added at two levels was recovered from real samples. The method was applied to the determination of EDTA in various foods, and the results obtained were compared with those given by high-performance liquid chromatography.

An enzymic method for the determination of nicotinic acid is described, based on the indirect electrochemical monitoring of nicotinic acid via its reaction with oxygen in the presence of nicotinic acid hydroxylase. Derivative amperometric signals due to oxygen depletion enable a one-point kinetic analysis to be carried out. Nicotinic acid hydroxylase catalyses the hydroxylation of nicotinic acid to produce 6-hydroxynicotinic acid, which is accompanied by a stoichiometric consumption of oxygen. The method was applied successfully to the analysis of real samples.

A multiple prompt gamma-ray analysis (MPGA) system was constructed at a cold neutron beam line of JRR-3 at Japan Atomic Energy Agency (JAEA). The system consists of 8 clover Ge detectors and BGO Compton suppressors. The detection limits for 41 trace elements with this system were determined. The MPGA system has low detection limits to elements such as B, Sc, Cd, Hg, Sm. We expect the MPGA system is a useful tool for analyses of toxic elements, heavy metals and rare-earth elements.