STABLE ISOTOPE-DILUTION METHOD FOR THE DETERMINATION OF SERUM GLUCOSE USING DISCHARGE-ASSISTED THERMOSPRAY LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY

A discharge-assisted thermospray liquid chromatography/mass spectrometric method for the determination of serum glucose was studied. Isotope dilution technique was used with uniformly labelled (C-13-6) glucose as an internal standard. Successful liquid chromatography/mass spectrometry was achieved by post-column addition of aqueous ammonium acetate to the mobile phase. Quantification was performed by measuring the peak intensity ratios of the unlabelled and labelled [M + NH4]+ ions. Analytical results using the National Institute of Standards and Technology standard reference material serum showed satisfactory agreement with the certified value, and a relative standard deviation of about 1% was obtained.