Determination of [Glu¹]-fibrinopeptide B purity by gas chromatography - isotope dilution mass spectrometry

The present work assessed the purity of [Glu(1)]-fibrinopeptide B (GFB) as a model peptide using gas chromatography - isotope dilution mass spectrometry. GFB and various isotope-labeled amino acids were hydrolyzed in HCl and then derivatized using optimized procedures. The primary impurity in GFB was also identified and used to correct the final result. A method repeatability of 0.5% was achieved and linear calibrations were obtained for five amino acids. The LOD and LOQ were 0.041 to 0.096 mu g g(-1), and 0.16 to 0.56 mu g g(-1), respectively. The purity of GFB was found to be (0.715 +/- 0.012) g g(-1). This technique exhibited comparable accuracy to that obtainable from liquid chromatography - isotope dilution mass spectrometry but at lower cost. This method could be employed as a reference technique or in fields such as clinical diagnostics or bio-pharmaceutical peptide purity analysis.