Determination of gamma-Aminobutyric acid by HPLC: Its application to polymeric Nanoparticles and stability studies

HPLC analysis of gamma-aminobutyric acid (GABA) and its relevant application to the unique polymeric nanoparticles (PNP) is described in this study. GABA is a major inhibitor neurotransmitter which is widely distributed in the central nervous system. Changes in GABA metabolism may play an important role in the origin and spread of seizure activity in epilepsy. Therefore, determination of GABA level is very significant in epilepsy treatment. In this study, determination of GABA in formulations was performed by HPLC using a developed validated method based on ICH Q2(R1). The best parameters were determined for HPLC analysis: optimized mobile phase of methanol:disodium hydrogen phosphate buffer (Na2HPO4) (40:60, v/v) (pH 6.7) at a flow rate of 0.8 mL.dk-1, injection volume 27 µL. Fluorescence detection was performed at an excitation wavelength of 280 nm and an emission wavelength of 450 nm and the column temperature was set to 30ºC. Ortophthalaldehyde/β-mercaptoethanol (OPA/BME) was used as the derivatization agent. Specified working range was derived from linearity studies and was kept in the range of 0.6-1.4 µg.mL-1. Good correlation, accuracy and precision values were obtained. Limit of detection (LOD) and limit of quantification (LOQ) were calculated to be 0.0107 and 0.3239 µg.mL-1, respectively. In stability studies GABA recovery from the PNPs stored at 4 ± 1ºC, 25 ± 1ºC, 40 ± 1ºC and 40 ± 1ºC-60 % relative humidity (RH) for 3 months were investigated and compared to the freshly prepared samples statistically. The HPLC method developed in this study is rapid, simple and suitable for routine analysis of GABA in PNPs.