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.
| Original language | English |
|---|---|
| Pages (from-to) | 1239-1243 |
| Number of pages | 5 |
| Journal | Clinica Chimica Acta |
| Volume | 413 |
| Issue number | 15-16 |
| DOIs | |
| Publication status | Published - 16 Aug 2012 |
Keywords
- 25-Hydroxyvitamin D
- LC-MS/MS
- Standardisation
- DEQAS
- VITAMIN-D STATUS
- CIRCULATING 25-HYDROXYVITAMIN-D
- SAMPLE PREPARATION
- D ASSAYS
- ACCURACY
- SERUM
- BIOANALYSIS
- METABOLITES
- INFANTS