Determination of the immunosuppressant mycophenolic acid in human serum by solid-phase microextraction coupled to liquid chromatography

A solid phase microextraction (SPME)-HPLC-UV method for the determination of the immunosuppressant mycophenolic acid (MPA) in human serum samples was developed for the first time. The procedure, that employed a carbowax/templated resin (Carbowax/TPR-100) as fiber coating, required a very simple sample pretreatment, an isocratic elution, and provides an highly selective extraction. The linear range was 0.2-100 microg x ml(-1). Recovery was practically unchanged (63+/- 4%) passing from 0.2 to 100 microg x ml(-1) level. Within-day and between-days coefficient of variation ranged from 5.9 to 6.5% and from 8.8 to 9.2%, respectively. A detection limit of 0.05 microg x ml(-1) was estimated in spiked serum. The method was successfully applied to the determination of MPA in serum of a patient under mycophenolate mophetil ester (MMF) therapy, as demonstrated by the relevant concentration-time profiles.