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Variability in the analysis of 25-hydroxyvitamin D by liquid chromatography-tandem mass spectrometry: The devil is in the detail

Research output: Contribution to journalArticle

Lewis Couchman, Christopher M. Benton, Caje Moniz

Original languageEnglish
Pages (from-to)1239-1243
Number of pages5
JournalClinica Chimica Acta
Volume413
Issue number15-16
DOIs
Publication statusPublished - 16 Aug 2012

King's Authors

Abstract

Background: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is increasingly used in clinical laboratories for the analysis of 25-hydroxyvitamin D (25OHD), but measurement is not straightforward. Importantly. LC-MS/MS is not a single technique: variables in sample preparation, chromatography and ionisation/fragmentation should each be considered.

Methods: We analysed results from a survey organised by the international Vitamin D External Quality Assessment Scheme (DEQAS), to determine the influence of such variables on the results for two DEQAS distributions.

Results: 65 laboratories returned questionnaires. 346 (57%) individual results were from laboratories using electrospray ionisation (ESI), and 259 (43%) from laboratories using atmospheric pressure chemical ionisation (APCI). Although the mean ratio of results was not significantly different between ESI and APCI (P = 0.5828), there was greater variation (P

Conclusions: There are many variables to consider when using LC-MS/MS, including assay standardisation/calibration, chromatography and MS conditions. MS/MS alone cannot distinguish isobaric metabolites such as 3-epi-25OHD(3). Interference can also occur if non-specific transitions are used. Laboratories should always subscribe to an EQA scheme for 25OHD analysis.

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