One millilitre of rice extract sample was added to 0.5 ml of
borax buffer pH 8 and 0.5 ml of HN (0.3% w/v in
methanol). The solution was heated in a water bath at 80C
for 10 min and was allowed to cool. The standard curve
was constructed from five standard solutions of GABA
(250, 125, 50, 25 and 10 ppm of GABA) analyzed by the
modified procedure of Khuhawar and Rajper 2003.