Quantitation of simvastatin and its beta-hydroxy acid in human plasma by liquid-liquid cartridge extraction and liquid chromatography/tandem mass spectrometry

J Mass Spectrom. 2000 Sep;35(9):1133-43. doi: 10.1002/1096-9888(200009)35:9<1133::AID-JMS42>3.0.CO;2-X.


A sensitive and reliable procedure for the simultaneous determination of simvastatin (SV) and its active beta-hydroxy acid metabolite (SVA) in human plasma was developed and validated. The analytes were extracted simultaneously from 0.5 ml aliquots of human plasma samples by methyl tert-butyl ether (MTBE) via Chem Elut cartridge extraction [also called liquid-solid extraction (LSE) or liquid-liquid cartridge extraction (LLCE)], separated through a Kromasil C(18) column (50 x 2 mm i.d. 5 microm) and detected by tandem mass spectrometry with a turbo ionspray interface. Stable isotope-labeled SV and SVA, (13)CD(3)-SV and (13)CD(3)-SVA, were used as internal standards. SV and SVA were detected in positive and negative ion modes, respectively, via within-run polarity switching. The use of Chem Elut cartridges not only provided a simple and efficient means of plasma sample extraction but also successfully reduced the interconversion between SV and SVA to an undetectable (for lactonization of SVA) or negligible (<0.07%, for hydrolysis of SV) level. The method showed excellent reproducibility, with intra- and inter-assay precisions <4.5% (RSD), and intra- and inter-assay accuracy between 94% and 107% of nominal values, for both analytes. The extraction recoveries were 78% and 87% on average for SV and SVA, respectively. The analyte was found to be stable in plasma through three freeze (-70 degrees C)-thaw (4 degrees C) cycles and for at least 3 h under bench-top storage condition in an ice-bath (4 degrees C), and also in the reconstitution solution at 4 degrees C for at least 24 h. The method has a lower limit of quantitation (LOQ) of 50 pg ml(-1) with a linear calibration range of 0.05-50 ng ml(-1) for both analytes, and has proved to be very reliable for the analysis of clinical samples.

MeSH terms

  • Anticholesteremic Agents / blood*
  • Calibration
  • Chromatography, Liquid
  • Humans
  • Indicators and Reagents
  • Mass Spectrometry
  • Quality Control
  • Reference Standards
  • Reproducibility of Results
  • Simvastatin / analogs & derivatives*
  • Simvastatin / blood*


  • Anticholesteremic Agents
  • Indicators and Reagents
  • simvastatin acid
  • Simvastatin