A validated method for gas chromatographic analysis of gamma-aminobutyric acid in tall fescue herbage.
Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter in animals that is also found in plants and has been associated with plant responses to stress. A simple and relatively rapid method of GABA separation and quantification was developed from a commercially available kit for serum amino acids (Phenomenex EZ:faast) and validated for tall fescue (Festuca arundinacea). Extraction in ethanol/water (80:20, v/v) at ambient temperature yielded detectable amounts of GABA. Clean separation from other amino acids in 28 min was achieved by gas chromatography (GC) with flame ionization detection (FID), using a 30 m, 5% phenyl/95% dimethylpolysiloxane column. The identity of the putative GABA peak was confirmed by GC with mass spectrometric (MS) detection. The relatively small effects of the sample matrix on GABA measurement were verified by demonstrating slope parallelism of GABA curves prepared in the presence and absence of fescue extracts. Limits of quantification and detection were 2.00 and 1.00 nmol/100 microL, respectively. Method recoveries at two different spike levels were 96.4 and 94.2%, with coefficients of variation of 7.3 and 7.2%, respectively.
Kagan
Isabelle A
IA
Forage-Animal Production Research Unit, Agricultural Research Service, United States Department of Agriculture, Lexington, Kentucky 40546, USA. isabelle.kagan@ars.usda.gov
Coe
Brenda L
BL
Smith
Lori L
LL
Huo
Cheng-Jun
CJ
Dougherty
Charles T
CT
Strickland
James R
JR
D000596:Amino Acids / Q000032:analysis; D002849:Chromatography, Gas / Q000379:methods*; D031751:Festuca / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D005680:gamma-Aminobutyric Acid / Q000032:analysis*
D000596:Amino Acids; D010936:Plant Extracts; D011933:Reagent Kits, Diagnostic; D005680:gamma-Aminobutyric Acid