METHOD AND KIT FOR ISOTOPE-LABELLING OF A FOLATE-CONTAINING BIOLOGICAL SAMPLE FOR MASS SPECTROMETRY

摘要

The present invention provides a method of stabilising a biological sample comprising at least two folate species. The method comprises providing the biological sample and contacting the folate species with a reducing agent and an aliphatic aldehyde or ketone under conditions which allow reductive alkylation of at least one of the folate species, wherein the reducing agent is a deuterated reducing agent, such as formaldehyde-¹³C, D₂, and the aliphatic aldehyde or ketone is a deuterated aliphatic aldehyde or ketone, such as cyanoborodeuteride, whereby at least one stabilised folate species isotopically labelled with D is obtained. Also provided is a biological sample containing at least one stabilised folate species selected from the group consisting of compounds I-VIII, as well as a mass-spectrometric method for quantifying folate species in the biological sample and a kit for stabilising a biological sample comprising at least two folate species for mass spectrometric analysis.