MoP-06



THE DETERMINATION OF GLYCATED HEMOGLOBIN BY MASS SPECTROMETRY

Michael Morris, Brian N Green and Norman B. Roberts*

Micromass UK Ltd, Tudor Road, Altrincham, Cheshire WA14 5RZ
*Department of Clinical Chemistry, Royal Liverpool University Hospital, Liverpool L69 3BX



The measurement of glycohemoglobin (GHB), also called glycated hemoglobin, is widely accepted as a valuable indicator for long-term diabetic control. Several procedures and numerous commercial instruments, mainly based on chromatographic methods, have been developed for measuring levels of GHB, but can give quite different results unless carefully calibrated against a reference 'standard'. Interferences, for example as the result of storage conditions, uremia, hemoglobinopathies and aspirin therapies, can also affect the results.

Electrospray ionisation mass spectrometry has been in use for a number of years for the characterisation of hemoglobins introduced in a denatured state into the mass spectrometer. This has allowed the molecular mass determination of normal and mutated globin species, which has been shown to be a useful adjunct to other analytical methods in the determination of amino acid substitutions in abnormal hemoglobin.

An electrospray mass spectrometric procedure has been developed for the determination of GHB. The procedure gave good precision and reproducibility (better than 3% CV) for inter- and intra-batch analyses. The mass spectrometric results compared favourably with a number of other established techniques based on ion-exchange chromatography and affinity chromatography. A typical inter-sample time, including data acquisition and processing, was less than three minutes.

The methodology and results of the glycated hemoglobin determination will be presented, in addition to the results from the comparison study of a batch of samples previously analysed by other methods.