A rubber transfer gasket to improve the throughput of liquid-liquid extraction in 96-well plates: Application to vitamin D testing

Background The unmitigated rise in demand for the assessment of vitamin D status has taxed the ability of clinical mass spectrometry laboratories to preserve turn-around times We aimed to improve the throughput of liquid-liquid extraction of plasma/serum for the assay of 25-hydroxy vitamin D Methods We designed and fabricated a flexible rubber gasket that seals two 96-well plates together to quantitatively transfer the contents of one plate to another Using the transfer gasket and a dry-ice acetone bath to freeze the aqueous infranatant, we developed a novel liquid-liquid extraction workflow in a 96-well plate format. We applied the technology to the mass spectrometric quantification of 25-hydroxy vitamin D. Results Cross-contamination between wells was <= 0.13% The interassay imprecision over 132 clays of clinical implementation was less than 10% The method compared favorably to a standard liquid-liquid extraction in glass tubes (Deming slope= 1 018, S-x vertical bar y = 0 022) The accuracy of the assay was 102-105% as assessed with the recently released control materials from NisT Conclusions: The development of a plate-sealing gasket pet nuts the liquid-liquid extraction of clinical specimens in a moderate-throughput workflow and the tellable assay of vitamin D status. In the future, the gasket may also prove useful in other sample preparation techniques for HPLC or mass spectrometry. (C) 2010 Elsevier B V. All rights reserved