High sensitivity determination of valproic acid in mouse plasma using semi‐automated sample preparation and liquid chromatography with tandem mass spectrometric detection

Abstract

A high-throughput liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) assay using automated sample preparation has been developed for the determination of valproic acid (VPA) in mouse plasma. A liquid-handling system was programmed to prepare calibration standard solutions in plasma, as well as quality controls and clinical samples. Plasma protein precipitation was performed on a 96-well plate, and the collected supernatant was directly injected into a reversed-phase LC/ESI-MS/MS system in the negative ionization mode. The calibration curve for VPA was linear over a dynamic range of 0.15-100 microg/mL. The limit of detection was 75 ng/mL and the lower limit of quantitation was 150 ng/mL. Intra- and inter-day validation assays of the semi-automated plasma analysis showed satisfactory accuracy and precision.

A simple and rapid determination of valproic acid in human plasma using a non‐porous silica column and liquid chromatography with tandem mass spectrometric detection

“…The typical retention times of VPA and IS were 1.2 and 1.8 min, respectively. The retention time of hexanoic acid, which was used as an internal standard by Pucci et al (2005), was 1.2 min on the non-porous column (negative mode ESI, MRM transition m /z 114.97-114.97, cone voltage 26 V, collision energy 10 eV). Therefore, we chose IS (betamethasone valerate) instead of hexanoic acid, which was not separated from VPA by the non-porous column.…”

“…However, most of these methods are time-consuming due to the complicated procedures for sample preparation, derivatization and extraction. On the other hand, several LC-MS(/MS) methods have been recognized as a powerful tool for the determination of VPA (Mino et al, 2001;Ramakrishna et al, 2005;Pucci et al, 2005). An LC/atmospheric pressure chemical ionization-MS method has also been reported to detect 5 -1000 μg/mL VPA without chemical modification of the compound, although the proposed method requires a laborious and time-consuming sample purification procedure that involves liquid-liquid extraction on an Extrelut column (Mino et al, 2001).…”

“…This method requires 200 μL of plasma specimens to conduct solid-phase extraction, achieving linearity ranging from 0.5 to 60 μg/mL, the upper limit of which nearly corresponds to the lower limit of the therapeutic VPA concentration. Recently, LC/ESI-MS/MS with enhanced mass resolution and automated sample preparation has also been developed (Pucci et al, 2005). However, in a number of LC methods for VPA assay, a conventional porous silica column is used for separation (Kushida and Ishizaki, 1985;Lingeman and Underberg, 1990;Amini et al, 2006;Lin et al, 2004;Mino et al, 2001;Ramakrishna et al, 2005;Pucci et al, 2005).…”

A New High-Throughput LC-MS/MS Assay for Therapeutic Level Monitoring of Valproic Acid in Human Plasma

“…Pucci et al [15] have also determined VA by LC-MS/MS after PP from mouse plasma and have obtained a good sensitivity (lower limit of quantification -LLOQ was 150 ng/mL). However, as the therapeutic plasma levels of VA are generally between 50-120 μg/mL [1,2], the LLOQ of 5 μg/mL established in our method can be accepted in routine purposes for therapeutic drug monitoring of VA in human plasma.…”

“…Sample preparation is more simple and rapid and often includes precipitation of proteins (PP) [15] and/or extraction [11][12][13][14] before chromatographic analysis.…”