Fast determination of valproic acid in plasma samples from poisoning cases using HybridSPE-precipitation and LC-MS/MS

Valproic acid (VPA) is an antiepileptic drug for epilepsy, as well as other neurological and psychiatric disorders, such as seizures, bipolar disorders, and migraines. It acts as a central nervous system depressant and is linked to overdose cases, often intentionally for suicidal purposes. Toxic plasmatic levels of VPA can result in various clinical manifestations, including drowsiness, ataxia, coma, and liver and kidney dysfunction. The rising cases of poisoning underscore the importance of identifying toxic agents for effective patient management and treatment, ensuring a positive prognosis. This study developed and validated an LC-MS/MS method to analyze VPA in plasma samples in emergency toxicology scenarios. Sample preparation was carried out using HybridSPE-PPT and used 100 μL of plasma. The total chromatographic run time was 4 min. The method was validated following the recommendations of the ANSI/ASB Standard 036 Guideline. The lower limit of quantification was 20 μg/mL and the method proved to be linear (r² > 0.999) up to 500 μg/mL. The developed method proved to be precise and accurate, with within-run and between-run precision CV% lower than 9 % and bias within -10.4 %. The matrix effect ranged from 113.3 to 128.5 % and the HybridSPE-PPT recovery rate was greater than 90 %. As proof of applicability, thirteen plasma samples from suspected poisoning cases were analyzed. The concentration found in the samples ranged from 21.1 μg/mL to > 500 μg/mL. A fast and simple LC-MS/MS method using the HybridSPE-PPT technique for quantifying VPA in plasma samples was successfully developed and validated.