The accurate determination of serum glucose by isotope dilution mass spectrometry—two methods

Two isotope dilution mass spectrometric methods have been developed for the determination of D‐glucose in human serum. Each uses a uniformly labeled ( 13 C)glucose as the internal standard. The first method involves conversion of glucose into 1,2: 5,6‐di‐ O ‐isopropylidene‐α‐ D ‐glucofuranose and an extensive clean‐up, followed by quantitation using packed column gas chromatography mass spectrometry. In the second method, glucose is converted into α‐ D ‐glucofuranose cyclic 1,2: 3,5‐bis(butylboronate)‐6‐acetate. The wet chemistry work‐up is simpler, but analysis by capillary gas chromatography mass spectrometry is required. Both methods exhibit excellent precision (coefficients of variation <0.3%) and provided mean values that agree within 1% for all serum pools tested.