Simple liquid chromatography–electrospray ionization mass spectrometry method for the routine determination of salmon calcitonin in serum

A simple liquid chromatography–electrospray ionization mass spectrometry (LC–ESI-MS) method was developed for the quantification of salmon calcitonin (sCT) in serum. Serum samples from rats and dogs were deproteinized and freeze-dried. The residue was then reconstituted with 57% acetonitrile in water containing 0.1% trifluoroacetic acid and 0.005% benzalkonium chloride. A 20-μl aliquot of the reconstituted solution was injected onto a polymer based RP-C18 column, The outlet was connected to an ion-trap mass spectrometer equipped with an ESI source, and spectra were recorded in a positive-ion, selected-ion monitoring mode. The limit of quantification of the method was 10 ng/ml. Biexponential curves were observed for the temporal serum concentration of sCT following intravenous administration of sCT to rats (100 μg/kg) and dogs (250 μg/kg), resulting in reasonable pharmacokinetic parameters. The present method appears applicable to routine analysis of serum sCT in pharmacokinetic studies with good selectivity, accuracy and precision.