Gas chromatographic determination of thiofanox residues in soil, plants, and water

Abstract

GC DETERMINATION OF THIOFANOX RESIDUES tion curves indicate the presence of carboxylate ions that could be explained by the presence of Na salts of some organic acids as impurities.Elementary analyses of the model substance gave the simplest empirical formula of CigH260nN, whereas the empirical formula of the isolate from barley roasted at 250°f or 40 min was found to be CigHgvOnN. Elementary analysis of both the model substance and the isolate from roasted barley indicated that they are of similar composition.The manner by which nitrogen is chemically bound in the brown substance, produced by the process of nonenzymatic browning after the temperature treatment, is not understood. The concentration of the brown substance in roasted barley was unexpectedly high. However, it can be explained by the fact that nonenzymatic browning occurs in two ways. The first occurs from the reaction between amino acid and reducing sugar, and the second occurs from caramelization, which can, but need not, include nitrogen.Isolation of the brown pigments from roasted barley by means of ion-exchange resin Permutit ES confirms that the substance is of an ionic nature and has a negative charge. According to the results obtained from uv and ir spectra (Figures 1 and 2) and from elementary analysis it was concluded that the isolate of the brown substance from roasted barley was of similar composition to the model substance. ACKNOWLEDGMENTThe able technological assays of M. Glogovcan are grate-fully acknowledged.

Changes of thiofanox residues in potatoes resulting from storage and cooking

“…Cooking Effects on Pt. Based on the results obtained, it is concluded that cooking potatoes may reduce or detoxify the anticholinesterase carbamate residues derived from thiofanox in two ways: (1) Baking and frying potatoes at or above 200 °C may reduce the anticholinesterase residues of thiofanox 50 to 90% through the chemical hydrolysis of P2 to O2 which is 386 times less toxic than P2 (Chin et al, 1975). ( 2) Boiling potatoes at 100 °C may reduce the anticholinesterase residues of thiofanox 30 to 60% through physical extraction of P2 from the boiled potatoes by the boiling water.…”

“…Pi residues in the potato samples were first oxidized to P2 and the total anticholinesterase carbamate residues derived from thiofanox (Pt, Pt = P + Pi + P2) were determined in the form of total P2 (Chin et al, 1975). For studying the relative quantities of P, Pi, P2, and O2 in potatoes, some samples with high Pt levels were selected from the 1972 and 1973 treatments for the determination of these residues individually.…”

“…Residues in the baked and boiled potatoes were analyzed using the published procedures for analyzing fresh potatoes. The fried potatoes were analyzed using the published procedures for cottonseeds, except 2 X 500 ml of acetone was used instead of dichloromethane (Chin et al, 1975).…”

Mechanism of degradation of thiofanox in aqueous solutions

“…An overall summary of the degradation of P at pH 10 is given in Figure 1. Because P2 is the most significant degradation product of P and has the highest toxicity of the three carbamates, the hydrolysis of P2 to O2, which toxicity is 386 times less than that of P2 (Chin et al, 1975), may be regarded as a detoxifying process.…”

Metabolism of thiofanox in cotton plants

“…; Madera, Meloland, and Wasco, Calif.; Albany, Pinehurst, Tifton, and Vienna, Ga.; Roanoke-Rapids, N.C.; Florence, S.C.; College Station, San Perlita, Thompson, and Waco, Tex.). The cottonseeds harvested at the end of the season were analyzed for total carbamate residues using a Tracer 550 gas chromatograph (Chin et al, 1975).…”