Measurement of urinary F(2)-isoprostanes by gas chromatography-mass spectrometry is confounded by interfering substances.
Analysis of F(2)-isoprostanes in urine using gas chromatography-mass spectrometry is confounded by the presence of endogenous compounds interfering with the internal standard, 15-F(2t)-IsoP-d(4) (m/z 573). Previous efforts to resolve the 15-F(2t)-IsoP-d(4) from co-eluting peaks with different solid phase extractions were unsuccessful. This study has now used a highly-deuterated, d(9)-analogue of the derivatization agent N,O-Bis(trimethyl-d(9)-silyl) trifluoroacetamide (BSTFA-d(9)) yielding trimethylsilyl ethers, but this was not successful in resolving the 15-F(2t)-IsoP-d(4) from co-eluting peaks. It was hypothesized that interfering peaks at m/z 573 could be the tetrahydro analogue of 15-F(2t)-IsoP. However, using an authentic standard showed the interfering peaks are not due to this metabolite. In subsequent experiments good resolution was shown of the 15-F(2t)-IsoP peak using 8-F(2t)-IsoP-d(4) (m/z 573) as the internal standard. These data show that care must be taken when using GC-MS for quantitation of F(2)-IsoPs to prevent interfering substances affecting the results.
Mas
Emilie
E
School of Medicine and Pharmacology, Royal Perth Hospital Unit, University of Western Australia and the Cardiovascular Research Center, Perth, Australia. emilie.mas@uwa.edu.au
Barden
Anne
A
Durand
Thierry
T
Galano
Jean-Marie
JM
Croft
Kevin D
KD
Mori
Trevor A
TA
D028441:F2-Isoprostanes / Q000138:chemical synthesis / Q000737:chemistry / Q000652:urine*; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008968:Molecular Conformation; D012016:Reference Values
D028441:F2-Isoprostanes