HPLC QUANTITATION OF FENITROTHION AND 3-METHYL-4-NITROPHENOL IN BIOLOGICAL-FLUIDS AFTER PREPACKED CARTRIDGE EXTRACTION AND ITS APPLICATION TO A POISONING CASE

We describe here the simultaneous determination of fenitrothion and it s metabolite, 3-methyl-4-nitrophenol (MNP), in biological fluids by HP LC after SepPakC18 cartridge extraction and its application to a human poisoning case. One mi of serum or urine mixed with an equal volume o f 0.1 N HCl was applied to the SepPakC18 cartridge, which was preactiv ated using methanol (5 mi), hexane/isopropanol (9/1 v/v, 10 mi), metha nol (5 mi) and distilled water (5 mi). After washing by 0.1N HCl(5 mi) , the eluate with 5 mi of hexane/isopropanol (9/1 v/v) was concentrate d, and the residue was dissolved in 100 mu l of methanol containing me thaqualone (internal standard, 30 mu g/ml). A 20 mu l of the aliquot w as injected into the HPLC. Recovery yields of fenitrothion and MNP fro m serum and urine ranged from 78.5-93.3%. Linear calibration curves fo r fenitrothion and MNP were in the range 0.1 - 10 mu g/ml. In a human poisoning case at 18.5 hrs after ingestion of Sumithion, concentration s of fenitrothion and MNP in serum were 11.8 and 3.9 mu g/ml and those in urine were less than 0.01 mu g/ml and 2.8 mu g/ml, respectively.