A new method for low level determination of the 25-monohydroxy-metabolites of vitamin D2 and D3 in plasma has been developed by Spark Holland. The assay is completely acetonitrile free avoiding problems associated with the current acetonitrile shortage. Quantitation levels of around 1ng/mL are reported using the Symbiosis system for HPLC with integrated Solid Phase Extraction linked to an Applied Biosystems API 4000 Mass Spectrometer. The assay involves almost no manual handling: plasma samples are diluted with a newly developed protein disrupting buffer which also contains the internal standard. Samples are then placed in the autosampler for direct injection into the SPE-LC-MS/MS system. The method shows excellent linearity, precision and carry-over and runs in only four minutes, including SPE.
A new method for low level determination of the 25-monohydroxy-metabolites of vitamin D2 and D3 in plasma has been developed by Spark Holland. The assay is completely acetonitrile free avoiding problems associated with the current acetonitrile shortage. Quantitation levels of around 1ng/mL are reported using the Symbiosis system for HPLC with integrated Solid Phase Extraction linked to an Applied Biosystems API 4000 Mass Spectrometer. The assay involves almost no manual handling: plasma samples are diluted with a newly developed protein disrupting buffer which also contains the internal standard. Samples are then placed in the autosampler for direct injection into the SPE-LC-MS/MS system. The method shows excellent linearity, precision and carry-over and runs in only four minutes, including SPE.
