Determination of p-nitrophenol in serum and urine by enzymatic and non-enzymatic conjugate hydrolysis and HPLC. Application after parathion intoxication.

In connection with the toxicologic analysis of a number of parathion intoxications a method for determination of free and conjugated forms of p-nitrophenol (p-NP) as the main metabolite of parathion in blood and urine was established. Quantification of conjugates is based on their hydrolysis followed by detection of p-NP using a sensitive HPLC method. Hydrolysis of both p-NP-glucuronide and p-NP-sulfate is performed by specific enzymes and also by mineral acid, the latter is also found to be highly selective under definite conditions. The two hydrolysis methods applied showed a good correlation. The levels of free and conjugated p-NP in series of blood and urine samples were established after survival from two parathion intoxications. The individual levels of p-NP-sulfate and p-NP-glucuronide in both cases are discussed in respect of results made by other authors in this field.