Sequential ethoxycarbonylation, methoximation and tert-butyldimethylsilylation for simultaneous determination of amino acids and carboxylic acids by dual-column gas chromatography.
Amino acids (AAs) in alkaline solution were first ethoxycarbonylated with subsequent methoximation of keto acids (KAs). After acidification and solid-phase extraction, tert-butyldimethylsilylation was performed for direct analysis by gas chromatography (GC) on dual-columns with different polarities, which provided simultaneous separation of multiple amino acids, carboxylic acids (CAs) and keto acids, facilitating accurate peak confirmation based on matching with retention index sets characteristic of each analyte. The present method was linear (r2 > or = 0.9955) with good precision (0.1-9.4%) and accuracy (-8.6 to 9.9%), allowing simultaneous screening for diagnostic amino acids along with carboxylic acids and keto acids in urine from a phenylketonuria patient.
Paik
Man-Jeong
MJ
College of Pharmacy, Sungkyunkwan University, Suwon, Kyunggi-do 440-746, South Korea.
Kim
Kyoung-Rae
KR
D000596:Amino Acids / Q000032:analysis*; D002138:Calibration; D002264:Carboxylic Acids / Q000032:analysis*; D002849:Chromatography, Gas / Q000379:methods*; D013058:Mass Spectrometry; D017646:Organosilicon Compounds / Q000737:chemistry*; D010091:Oximes / Q000737:chemistry*; D012015:Reference Standards; D015203:Reproducibility of Results
D000596:Amino Acids; D002264:Carboxylic Acids; D017646:Organosilicon Compounds; D010091:Oximes; C009660:t-butyldimethylsilyl compounds