Chemical reagents
Standard γ-amino-n-butyric acid was
obtained from Sigma. Acetic acid, ethanol and
sodium acetate (analytical grade), were purchased
from Merck. Acetonitrile, of high performance
liquid chromatography (HPLC) -grade, was
purchased from Lab-Scan. Triethylamine and
phenyliso-thiocyanate (PITC) were obtained from
Unilab and Fluka, respectively.