Comparison of Serum Valproic Acid Determination Through Gas and High Performance Liquid Chromatography Methods

Background: Valproic acid is widely used as an anticonvulsant and mood-stabilizing drug in the treatment of epilepsy. Determination of serum valproic acid is required in epilepsy therapy for efficient control of seizures. Objectives: In the present study, the gas chromatography method was applied to determine serum valproic acid and resulting data were compared with those obtained by high performance liquid chromatography. Materials and Methods: Two methods were used: assayed patients' serum samples and serum quality control materials for laboratory diagnostics applied to high performance liquid chromatography (HPLC) and gas chromatography (GC). All chemicals had a grade suitable for analysis. Results: The obtained results in both systems were in agreement regarding linearity, correlation and recovery. The results revealed a lower GC limit of quantification (8 mu g/mL), a better intra-assay coefficient of variation (CV) (3.86% - 3.99%) and inter-assay CV (6.14% - 6.42%) for all three levels of control materials. In addition, a shorter run time of the GC vs. the HPLC chromatographic step (6 minutes vs. 17 minutes) was observed. Conclusions: The present study reports a short run time of the chromatographic step as well as a good sensitivity for the GC method. Furthermore, the significance of this method is the simplicity in sample preparation step without the need for derivatization and specific detector ensuring cost-effectiveness for the GC analysis. In summary, in comparison with HPLC method, our obtained data illustrate a good performance of the GC analytical procedure and confirm its usefulness for the routine quantification of valproic acid level in patients' serum specimens.