Determination of dansylated polyamines in red blood cells by liquid chromatography-tandem mass spectrometry.

The concentration of polyamines in red blood cells (RBCs) is considered to be an index of cell proliferation. This index has been demonstrated to be of clinical importance for the follow-up and treatment of some cancer patients. The concentration of polyamines in RBCs is usually determined by high-performance liquid chromatography (HPLC) with fluorescence detection. In the current work, we present a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of putrescine, spermidine, and spermine, the three major polyamines in RBCs. The polyamines were dansylated and analyzed by an LC gradient of 20-min duration on a C18 column on-line with a tandem mass spectrometer. An internal standard (1,8-diaminooctane) was used for quantification. This method exhibited excellent linearity for the three polyamines with regression coefficients higher than 0.99. The limits of detection for putrescine, spermidine, and spermine were 0.10, 0.75, and 0.50 pmol/ml, respectively. The intrarun precision values for putrescine, spermidine, and spermine all were better than 10%, and the interrun precision values were 13%, 9%, and 20%, respectively. The LC-MS/MS method is sufficiently simple and reliable enough to replace the currently used HPLC method with fluorescence detection in which putrescine is not always detectable.

A robust liquid chromatography tandem mass spectrometry method for total plasma homocysteine determination in clinical practice.

BACKGROUND: Total plasma homocysteine has emerged as an independent risk factor for vascular disease. To meet increasing requests by clinicians for this homocysteine determination, a rapid assay for a routine use has been developed. METHODS: A robust, stable, isotope-dilution liquid chromatography tandem mass spectrometry (LC/MS/MS) method is described, including all the practical details and analytical performance results. RESULTS: The method allows homocysteine quantitation over a linear working range up to 100 micromol/L, with the limit of quantification estimated at a low value of 0.09 micromol/L. Total analytical imprecision is less than 4%. Accuracy was assessed by measuring the homocysteine concentration in a serum Standard Reference Material. CONCLUSIONS: The method was demonstrated to be quick, reliable and cheap after 1 year of use on a time-shared instrument in our hospital unit.