Simultaneous HPLC determination of gamma amino butyric acid (GABA) and lysine in selected Pakistani rice varieties by pre-column derivatization with 2-Hydroxynaphthaldehyde

• Sensitive and selective HPLC method was developed for GABA and lysine.
• Both analytes were detected as Schiff base derivative in brown and polished rice varieties.
• 2-Hydroxynaphthaldehyde is used as a derivatizing reagent for detection of GABA and lysine.
• GABA and lysine contents were found higher in brown rice varieties as compared to polished rice varieties.

A selective and sensitive HPLC method for the simultaneous determination of gamma amino butyric acid (GABA) and lysine in Pakistani rice varieties was developed. Both analytes were detected in rice varieties as Schiff base derivatives with 2-hydroxynaphthaldehyde. The derivatives were analyzed on a reverse phase C-18 column with Diode Array Detector (DAD) at 254 nm. The calibration curves were found linear over a concentration range of 3.83–34.58 μg/mL for GABA and 5.16–48.68 μg/mL for lysine with a correlation coefficient of 0.998 for both standards. GABA and lysine contents were found higher in brown rice varieties (4.1–6.58 mg/100 g for GABA and 15.1–27.6 mg/100 g for lysine) than the polished varieties (0.32–0.47 mg/100 g GABA and 13.1–19.8 mg/100 g lysine). This method could be used for separation and quantification of GABA and lysine simultaneously in food samples, especially in cereal seeds.