INTRODUCTION AND OBJECTIVE: Acetaminophen or paracetamol is currently one of the most used analgesic-antipyretic agents, mainly with children. However, both the easy access to this medicine and the population’s unawareness of its toxic effects have contributed to a rise in the number of intoxications caused by this drug. Assessment of serum acetaminophen confirms the diagnosis. Not only does the result have diagnostic reliability but it also evaluates the risk of hepatotoxicity, indicating or not the administration of the specific antidote n-acetylcysteine. The aim of this study is to present an analytical method to the assessment of serum acetaminophen by spectrophotometric detection at 430 nm. MATERIALS AND METHODS: After sample deproteinization, acetaminophen (n-acetyl-p-aminophenol) reacts with sodium nitrite forming 2.4-nitro-4-acetaminophenol, which becomes yellowish in alkaline medium. For method validation, linearity, precision, accuracy, robustness, recovery and detection limits were evaluated according to ICH and ANVISA criteria. The stability study was carried out after freezing/defreezing cycles, short-time duration, long-time duration under refrigeration and long-time duration under freezing. RESULTS: The method showed to be linear from 20 to 300 mg/l. The detection and quantification limits were 3.6 mg/l and 20 mg/l, respectively. CONCLUSION: The method was precise, accurate and robust and showed good recovery. The control-samples were stable in all tested conditions. The method developed presented all the necessary parameters to be applied in acetaminophen quantification in plasma samples or human serum for emergency analyzes. Furthermore, it is a simple, time and cost-effective technique.
Acetaminophen; Serum quantification; Ultraviolet visible
