Development of automatic extraction-analysis system for thermospray mass spectrometer.

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We demonstrate an automatic, on-line extraction-analysis assay for benzodiazepines (bromazepam, estazolam and triazolam) by the column-switching system for three columns using thermospray liquid chromatograph-mass spectrometer and photodiode array detector. The benzodiazepines in serum were separated from the serum contents using a gel column (ASAHIPAK GS-310H C18,4.6mm ID*250mm L) and the mobile phase 1 (40% CH_3CN containing 0.1 N NaCIO_4 at a flow rate of 0.5ml/min), and then trapped to the second column (CAPCELL PAK C18,4.6mm ID*35mm L). Following the column-wash with the mobile phase 2 (distillled water at 1.5ml/min, for 5min), each drug was identified using the third column (STR ODS-2,4.6mm ID*250mm L) and the mobile phase 3 (50% CH_<3CN> containing 50 mM CH_3COONH_4 and 0.05% CH_3COOH,at 1.0ml/min). The benzodiazepines were detected thermospray mass spectrometer QP1000EX and photodiode array detector SPD-M10AVP.The temperature of the vaporizer, block and tip heater of the ion source block were set at 144,305 and 315 ﾟC,respectively. Peaks of bromazepam, estazolam and triazolam were represented 4.8,6.3 and 7.1 min, respectively. The recovery rates of the drugs in aqueous solution were 90.9,97.2 and 90.9%, respectively. The coefficients of variance for reproducibility of the drugs were 1.25,0.33 and 0.54%, respectively. When thermospray ionization was used, MH^+ ions of m/z 316,295 and 343 were obtained as base peak for bromazepam, estazolam and triazolam, respectively.