Rapid and sensitive determination of cyclosporins by pyrolysis mass spectrometry

Cyclosporin A (CsA) is a potent immunosuppressant widely used in human medi cine to prevent rejection of transplanted organs. Total concentration of Cs A and its metabolites in human blood was determined by pyrolysis mass spect rometry (pyr-ms). Mass to charge (m/z) values of 100 of CsA and 3-nitroanil ine as an internal standard were used for quantitative measurements by sele cted ion monitoring (SIM). Results of pyr-ms at 420 degrees C are highly re producible. Limit of detection (LOD) and linearity were determined to 0.7 n g ml(-1) and 0.7 ng ml(-1) - 100 mg ml(-1), respectively. LOD is improved t o 0.02 ng ml(-1) by using a solid phase extraction (SPE) disk. Results of p yr-ms are compared with those obtained by the high performance liquid chrom atography (HPLC) measurements.