Total and conjugated urinary paranitrophenol after an acute parathion ingestion

In a fatal case of acute parathion ingestion, paranitrophenyl sulphate, the paranitrophenyl glucuronide and free paranitrophenol excretion on day 3 were quantitated using a HPLC reverse method with a C18 column following sample preparation using a C18 mini-column and methanol elution. Paranitrophenyl sulphate amounted to about 81% of the total conjugates excreted. The results were confirmed by collecting the fractions identified by high-performance liquid chromatography, hydrolysing them with concentrated hydrochloric acid and quantitating paranitrophenol by gas chromatography. Total paranitrophenol excretion was also determined. The excreted paranitrophenol was equivalent to 76 mg parathion (lethal dose in humans between 20 and 100 mg). No changes in the concentrations of paranitrophenol or its conjugates were seen in the urine on storage, frozen over a one year period.