Rapid HPLC/UV method for analysis of urinary and plasma/serum paracetamol concentrations

Paracetamol is one of the most commonly used over-the-counter pain relievers and fever-reducers. However, overdosing of paracetamol causes liver damage which may lead to patients' death upon delayed treatment. To provide accurate diagnosis and fast treatment of paracetamol poisoning, rapid analysis of paracetamol in patient tissues is necessary. In this study a rapid and simple high performance liquid chromatographic method was developed to analyse plasma/serum and urinary paracetamol using 100 pi, of specimen. Paracetamol is chromatographically resolved, with an isocratic mobile phase followed by UV detection after protein precipitation. beta-Hydroxyethyltheophylline was used as the internal standard. The elution of paracetamol and the internal standard was achieved within 8 minutes. The calibration curve was linear over 0.25-200 mg/L. This method produced excellent accuracy and precision in all matrices tested. Intra and inter day variability was less than 5%. The limits of detection were 0.13 mg/L for plasma and 0.43 mg/L for urine, whereas the limits of quantification were 0.68 mg/L for plasma; and 2.25 mg/L for urine. No matrix effects were observed with endogenous substances. This method is applied to analyze paracetamol levels in serum of accidental or self poisioning patients.