Improved selectivity in detection of polar basic drugs by liquid chromatography-electrospray ionization mass spectrometry. Illustration using an assay method for the determination of famotidine in human plasma
Campanero MA, Bueno I, Arangoa MA, Escolar M, Quetglás EG, López-Ocáriz A, Azanza JR.
It is well to assume that bioanalytical chromatographic methods for the determination of polar basic drugs are developed and optimised according to a standardised procedure which involves two alternatives: (a) modifications in the sample preparation procedures, and (b) changes in the stationary phase of the chromatographic system. In this paper, a simple and rapid chromatographic procedure using a specific analytical detection method (ESI tandem mass spectrophotometric detection) in combination with a fast and efficient sample work-up procedure, protein precipitation, is presented.
A demonstration of the entire chromatographic procedure is given for an HPLC method for the determination of famotidine in human plasma, a basic polar drug with poor solubility in organic solvents. In order to optimize the mass detection of famotidine, several parameters such as ionization mode, fragmentor voltage, m/z ratios of ions monitored, type of organic modifier and eluent additive, were investigated. Each analysis required 5 min. The calibration curve of famotidine in the range 1-200 ng/ml was linear with a correlation coefficient of 0.9992 (n = 6), and a detection limit a signal-to-noise ratio of 3 was approximately 0.2 ng/ml. The within- and between-day variations in the famotidine analysis were 5.2 (n = 6) and 6.7% (n = 18), respectively.
The applicability of this method was also demonstrated for the analysis of plasma samples in a Phase-I human pharmacokinetic study.
CITATION J Chromatogr B Biomed Sci Appl. 2001 Nov 5;763(1-2):21-33