Further water solubility determinations of insecticidal compounds.

The aqueous solubility of 39 insecticidal and related compounds was determined at 20 +/- 1.5 degrees C, using a previously described shaking and centrifugation method. Fenamiphos, fenthion and methidathion produced values substantially less than those reported in the literature whereas, aminocarb, diazinon, dicapthon, pirimiphos-ethyl and pirimiphos-methyl gave solubilities substantially greater than reported literature values.

Adsorption, desorption, soil mobility, aqueous persistence and octanol-water partitioning coefficients of terbufos, terbufos sulfoxide and terbufos sulfone.

Terbufos, t.sulfoxide and t.sulfone (5 micrograms ml-1) were incubated in natural, sterilized natural and distilled water, with initial pH values of 8.8, 8.8 and 6.0, respectively, at 20 degrees C. First-order disappearance was observed for the three compounds. Rates in natural and sterilized water were similar indicating chemical degradation predominated. Terbufos disappeared rapidly (t1/2 congruent to 3 days) in all systems. T.sulfoxide and t.sulfone were more persistent in the natural (t1/2 = 18-40 days) and distilled water (t1/2 = 280-350 days). Adsorption data for the three compounds in four soil-water systems showed the decreasing order of adsorption to be terbufos much greater than t.sulfoxide congruent to t.sulfone. Desorption from soils fortified at 5 micrograms g-1 with water was examined for 4 successive 18-hr cycles. T.sulfoxide and t.sulfone were totally desorbed; terbufos was too unstable to study. The mobility of the compound in soil eluted with water was in the order, t.sulfoxide congruent to t.sulfone much greater than terbufos, in agreement with adsorption-desorption results. The octanol-water partitioning coefficients for terbufos, t.sulfoxide and t.sulfone, at 23 degrees C, were 3:30 x 10(4), 164, and 302, respectively.

Stability of parathion and DDT in dilute iron solutions.

Dilute FeCl3 and Fe(NO3)3 solutions degraded parathion to paraoxon and p-nitrophenol. Initial hydrolysis products of iron appeared to have the greatest catalytic activity which decreased as these hydrolysis products aged. The Fe3+ ion was less catalytically active than its hydrolysis products for parathion degradation. pH was not a factor in parathion degradation in this study. AlCl3 solutions did not degrade parathion over a 336 hour period. DDT was stable in dilute FeCl3 and Fe(NO3)3 solutions for at least 56 days.

The aqueous solubility of twenty-seven insecticides and related compounds.

The aqueous solubilities of 27 insecticides and related compounds were determined. Diazinon, fensulfothion and paraoxon had solubilities greater than reported in the literature. The presence of impurities and/or additional components in the mixture altered the measured solubility values. Addition of acetone in amounts up to 1% (volume) produced increases in parathion solubility up to 11%. The pH values of the equilibrated solubility systems were, in most instances, acidic and, in several instances, were in the pH 3-4 range.