Simultaneous determination of chlorothalonil and hexachlorobenzene in technical and formulated materials by capillary gas chromatography: collaborative study.

A collaborative study was conducted for the capillary gas chromatographic (GC) method for the simultaneous determination of the fungicide chlorothalonil (CTL) and the accompanying impurity, hexachlorobenzene (HCB), in technical and formulated materials. The method calls for the dissolution of technical and dry formulations of CTL and HCB from the aqueous flowable formulation. The 10 participating laboratories were asked to analyze the samples by adhering to the method as closely as their instrumentation and data systems allowed, and to note any deviations from the method.

Some characteristics of nitrate reductase from higher plants.

With respect to cofactor requirements, NADH, and FMNH(2) were equally effective as electron donors for nitrate reductase obtained from leaves of maize, marrow, and spinach, when the cofactors were supplied in optimal concentrations. The concentration of FMNH(2) required to obtain half-maximal activity was from 40- to 100-fold higher than for NADH. For maximal activity with the corn enzyme, 0.