Analysis of tetracyclines in raw urine by column-switching high-performance liquid chromatography and tandem mass spectrometry

The aim of the project was to develop a fast and reliable method for the qu antification of the three tetracyclines: tetracycline, oxytetracycline and chlortetracycline in urine. The method is based on column-switching high-pe rformance liquid chromatography with detection by MS-MS. Buffer is added to the sample before it is injected into the chromatographic system, and the first column which is an internal surface reversed-phase column separates t he tetracyclines from the bulk of other compounds in urine. The tetracyclin es are collected and concentrated on the analytical column before they are separated and eluted into the mass spectrometer in which the tetracycline a re detected. The mass spectrometer is a triple quadrupole instrument and is equipped with an electrospray ion source. The MH+ ions are selected in the first quadrupole and collisionally activated in the collision cell. Upon c ollision, activation all three tetracyclines form fragment ions which could be assigned as: [M+H-H2O-NH3](+) which are selected in the send mass filte r. The detection limits for all three tetracyclines are about 10 ppb, and t he calibration curves are Linear from 10 to 1000 ppb. (C) 1999 Elsevier Sci ence B.V. All rights reserved.