Comparison of validated high-performance liquid chromatography methods using two derivatizing agents for gamma-aminobutyric acid quantification

Objective: The purpose of this study was to validate and compare two HPLC analyses of GABA after derivatization with 2-hydroxynaphthaldehyde (HN) or with o-phthaladehyde (OPA) and 3-mercaptopropionic acid (MPA) in terms of reproducibility, sensitivity and stability of two derivatives. Materials and Methods: GABA was derivatized with either 2-hydroxynaphthaldehyde (HN) or with o-phthaladehyde (OPA) and 3-mercaptopropionic acid (MPA) and was analyzed and validated using two different HPLC methods. Results: Reliability resulted in satisfaction for the HPLC methods in each derivatizing agent. Linear correlation was obtained in the concentration ranges of 40-600 μg/ml and 0.2-0.9 μg/ml for GABA-HN and GABA-OPA/MPA, respectively. The low limit of detection (LOD) and the limit of quantification (LOQ) of GABA-HN were 1 μg/ml and 5 μg/ml while LOD and LOQ of GABA-OPA/MPA were 0.004 μg/ml and 0.02 μg/ml. Validation results of two methods with chosen derivatizing agents showed that the methods were reproducible and precise on quantification of GABA. The method with GABA-OPA/MPA derivatization revealed higher sensitivity compared to one with GABA-HN derivatization. However, GABA-OPA/MPA derivative was less stable. Conclusion: Both validated methods could be used for sensitive and accurate analysis of GABA.