Quantitation of berberine chloride in human urine by use of selected ion monitoring in the field desorption mode.

A method is described for the microdetermination of berberine chloride in human urine by a field desorption mass spectrometry selected ion monitoring system using a deuterium labelled analogue of berberine chloride as an internal standard. Prior to the quantitation of berberine in human urine, the fundamental problems related to field desorption selected ion monitoring, such as quality of emitters, amounts of sample loading, and the programming rate of the emitter current, were statistically investigated in detail. Berberine chloride can be determined in a concentration of 10 ng ml-1 in human urine by the method described. The analytical results were compared with those from gas chromatography mass spectrometry selected ion monitoring in the chemical ionization mode suggesting that the reliability of field desorption selected ion monitoring may be almost equivalent to that of gas chromatography chemical ionization selected ion monitoring.