Development of a HPLC/MS-MS method for the measurement of mevalonic acid in human plasma

Jenna Waldron and Craig Webster.

Department of Clinical Biochemistry and Immunology, Birmingham Heartlands Hospital.

Mevalonic acid (MVA) is synthesised at an early and rate-limiting step in the biosynthesis of cholesterol by the enzyme HMG-CoA reductase, and is a useful measure of statin efficacy or treatment. We have developed a specific and sensitive high performance liquid chromatography-tandem mass spectrometry for the measurement of MVA. Following its conversion to mevalonic acid lactone (MVAL), MVA, and a deuterated internal standard, were extracted from human plasma samples using solid-phase extraction. Chromatographic separation was achieved using a Luna PFP column (Phenomenex), which enables enhanced selectivity and improved resolution for polar compounds. An isocratic system was used with a mobile phase consisting of 15% methanol and ammonium formate buffer (5mM, pH 2.5), and a flow rate of 0.5 ml/min. Analysis was performed using an API 5000 tandem mass spectrometer (Applied Biosystems) and using an electrospray ESI source in positive mode. The instrument was tuned for the mass transitions of m/z 131?113 and 131?69. The retention times achieved for each transition allows for a total run time of 5 minutes. In conclusion, we have developed a method that is analytically specific and sensitive, and could potentially be used to determine the endogenous levels of MVA in normal individuals, and in patients undergoing statin treatment to aid in their lipid management.