Determination of Gamma Aminobutyric Acid: Ultraviolet Spectroscopic Method with 2-hydroxynaphthaldehyde Derivatization

Abstract

A simple and rapid ultraviolet spectroscopic method was developed and validated for the determination of gamma aminobutyric acid (GABA) concentration in biological samples. The GABA was extracted with a 75% ethanol solution and quantitated by derivatization with 2-hydroxynaphthaldehyde (3 mg/ml) and UV detection at 415 nm wavelength. The effects of pH, derivatizing reagent concentration, heating time, and the ideal wavelength for GABA derivative detection were assessed in order to optimize the UV detection conditions. The absorbance spectra of GABA and glutamic acid derivatives were measured and the optimal wavelength for GABA determination was 415 nm. The optimal derivatization condition giving a maximum response under UV detection; was characterized using Borax buffer at pH 8 and heating at 80 degree Celsius for 15 minutes. The solution of the 2-hydroxynaphthaldehyde derivative was found to be stable after 24-hour storage at room temperature. The validation and optimization showed a linear calibration curve in the GABA derivative concentration range of 0.1 to 2.0 mg/ml with the correlation coefficient of 0.996. The method was used in the determination of GABA in rice samples. The amounts of GABA in germinated brown rice samples were in the range of 19.4 – 26.6 mg/100 g dry weight. It varied due to the different germination processes, while those in polished rice samples were 2.1 – 6.3 mg/100 g dry weight. The GABA contents in germinated brown rice samples were higher than those in the polished ones. In conclusion, UV-detection with 2-hydroxynaphthaldehyde derivatization method was feasible, capable of GABA concentration measurement in rice and other biological samples.

Cite as:

Rakesh Sharma. (2024). Determination of Gamma Aminobutyric Acid: Ultraviolet Spectroscopic Method with 2-hydroxynaphthaldehyde Derivatization. Journal of Advances in Nanotechnology and Its Applications, 6(2), 7-13. https://doi.org/10.5281/zenodo.11203126