A sensitive method for 4-hydroxybutyric acid in urine using gas chromatography-mass spectrometry.
4-Hydroxybutyric acid (4HB) was analyzed by gas chromatography-mass spectrometry. Under acidified conditions, 4HB is difficult to detect due to lactonization. Using a urine sample containing 0.01 mg creatinine, we performed trimethylsilyl derivatization without extraction, only adding dimethylsuccinic acid as an internal standard and 10 microl of 0.1 N NaOH methanol solution with adequate evaporation. Urine 4HB levels in a patient with 4-hydroxybutyric aciduria was determined to be 1258 mmol/mol Cr (control, 0.28-2.81 mmol/mol Cr) in this method. Direct derivatization of samples without extraction showed good reproducibility and linearity. Only a small sample of urine was required. Alkalinization by NaOH prevented not only lactonization of 4HB, but also loss of the compounds during evaporation.
Kimura
Masahiko
M
Department of Pediatrics, Shimane Medical University, 89-1 Enya, Izumo, Shimane 693-8501, Japan. kimura@shimane-med.ac.jp
Hasegawa
Yuki
Y
Nakagawa
Katuhiro
K
Kajita
Mituharu
M
Watanabe
Kazuyoshi
K
Yamaguchi
Seiji
S
D002648:Child; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D006885:Hydroxybutyrates / Q000652:urine*; D012015:Reference Standards; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D006885:Hydroxybutyrates; C111420:4-hydroxybutyric acid