Markus R Meyer1, Jessica Welter, Armin A Weber, Hans H Maurer. 1. Department of Experimental and Clinical Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, University of Saarland, Homburg (Saar), Germany. markus.meyer@uks.eu
Abstract
BACKGROUND: To date, immunoassays are commercially available for quantification of valproic acid, salicylic acid, paracetamol, phenobarbital, phenytoin, and primidone. As they are no longer available, a fast, simple, and cost-effective quantitative gas chromatography-mass spectrometry (GC-MS) method was developed and fully validated for these drugs. METHODS: After simple and fast liquid-liquid extraction, the samples were analyzed by GC-MS using the selected ion monitoring mode. The method was validated including the parameters selectivity, calibration model, precision, accuracy, and extraction efficiency. RESULTS: The above-mentioned analytes were separated within 8.5 minutes and sensitively detected. No interfering peaks were observed in blank samples from 8 different sources. The linearity ranges were 20-200 mg/L for valproic acid, 100-1200 mg/L for salicylic acid, 10-200 mg/L for paracetamol, 10-200 mg/L for phenobarbital, 4-20 mg/L for primidone, and 2.5-30 mg/L for phenytoin. Generally accepted criteria for accuracy and precision were fulfilled for all analytes using 6-point calibration. Even 1-point calibration was applicable for all analytes. The assay was successfully applied to analysis of real plasma samples and proficiency testing material. CONCLUSIONS: The assay described allowed fast and reliable determination of analytes relevant in the diagnosis of poisonings. Furthermore, time- and cost-saving 1-point calibration was shown to be suitable for daily routine work, especially in emergency cases.
BACKGROUND: To date, immunoassays are commercially available for quantification of valproic acid, salicylic acid, paracetamol, phenobarbital, phenytoin, and primidone. As they are no longer available, a fast, simple, and cost-effective quantitative gas chromatography-mass spectrometry (GC-MS) method was developed and fully validated for these drugs. METHODS: After simple and fast liquid-liquid extraction, the samples were analyzed by GC-MS using the selected ion monitoring mode. The method was validated including the parameters selectivity, calibration model, precision, accuracy, and extraction efficiency. RESULTS: The above-mentioned analytes were separated within 8.5 minutes and sensitively detected. No interfering peaks were observed in blank samples from 8 different sources. The linearity ranges were 20-200 mg/L for valproic acid, 100-1200 mg/L for salicylic acid, 10-200 mg/L for paracetamol, 10-200 mg/L for phenobarbital, 4-20 mg/L for primidone, and 2.5-30 mg/L for phenytoin. Generally accepted criteria for accuracy and precision were fulfilled for all analytes using 6-point calibration. Even 1-point calibration was applicable for all analytes. The assay was successfully applied to analysis of real plasma samples and proficiency testing material. CONCLUSIONS: The assay described allowed fast and reliable determination of analytes relevant in the diagnosis of poisonings. Furthermore, time- and cost-saving 1-point calibration was shown to be suitable for daily routine work, especially in emergency cases.
Authors: Richard Kin-Ting Kam; Michael Ho-Ming Chan; Hiu-Ting Wong; Aniruddha Ghose; Arjen M Dondorp; Katherine Plewes; Joel Tarning Journal: Future Sci OA Date: 2018-08-15