GABA was extracted and derivatized to
phenylthiocarbamyl-GABA (PTC-GABA). After
derivatization, the dry residue containing PTCGABA
was dissolved in 200 μl of the mobile
phase. The supernatant was filtered using a nylon
membrane filter (13mm dia. 0.45 μm) and injected
into HPLC equipped with a column