Sensitive method for the determination of pentamorphone in serum by liquid chromatography-mass spectrometry with thermospray interface.

A liquid chromatographic-mass spectrometric method for the determination of 14-beta-n-pentylaminomorphinone (pentamorphone) and 14-beta-n-pentylaminocodeinone (PAC) as internal standard is developed. Concentration levels in serum were calculated by the ratio of the peak areas of pentamorphone to PAC versus the concentration of pentamorphone. Peak areas were measured using selected-ion-recording of the pseudo-molecular ions of pentamorphone and PAC (m/z 369 and m/z 383, respectively). Aliquots (50 microliters) of sample were injected on a C18 mu Bondapak column following solid-phase extraction. The lowest limit of quantitation observed was 43 pg/ml. The sensitivity, accuracy and reproducibility of the method were demonstrated to be satisfactory for application in pharmacokinetic study of pentamorphone.