Single-pair fluorescence resonance energy transfer (spFRET) for the high sensitivity analysis of low-abundance proteins using aptamers as molecular recognition elements.
(19/914)
Application of on-line electrochemistry/electrospray/tandem mass spectrometry to a quantification method for the antipsychotic drug zotepine in human serum.
(22/914)
A simple, rapid, and sensitive on-line liquid chromatographic electrochemistry/electrospray/tandem mass spectrometry (LC-EC/ESI-MS/MS) method for the determination of zotepine in human serum was developed using a new generated-electrochemically fragment ion, and was validated. A recent novel technique of LC-EC/ESI-MS/MS that combines LC-MS/MS and the on-line EC reaction is potentially applicable to developing a quantification method for drugs in biological samples. Newly formed products generated by the on-line EC cell are expected to provide appropriate precursor and product ions for the MS/MS determination method. This technique was successfully applied to a drug assay in a biological matrix. After adding imipramine (IS) to a 30-microL aliquot of human serum, the resulting sample was simply deproteinated with acetonitrile for a measurement. The analytical run time was 5 min. The calibration curve was linear in the concentration range of 10-2000 ng/mL. The intra-assay precision and accuracy were in the range of 1.8-8.9 and 98.4-113%, respectively. (+info)
Simultaneous determination of venlafaxine and its main active metabolite O-desmethyl venlafaxine in rat plasma by LC-MS/MS.
(23/914)
A simple, sensitive and selective liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for the analysis of venlafaxine (VX) and its major active metabolite O-desmethyl venlafaxine (ODV) in rat plasma using carbamazepine as an internal standard (IS). The analytes from the biological matrix were extracted by liquid-liquid extraction using tert-butyl methyl ether (TBME). The HPLC separation of the analytes was performed on a water symmetry C18 (150 x 4.6 mm i.d., 5 microm) column, using a 10 mM ammonium formate:methanol (20:80 v/v) as mobile phase. The calibration curve concentration range was 10.10 to 8000.00 ng/mL for VX and ODV with coefficient of determination above 0.9970. The lower limit of quantification (LLOQ) of VX and ODV were 3.35 and 3.86 ng/mL, respectively. The intra- and inter-day coefficients of variation were within 15%. (+info)
Simultaneous determination of tegafur and gimeracil in human plasma by liquid chromatography/tandem mass spectrometry.
(24/914)
We developed a rapid, simple and sensitive LC/MS/MS method for the simultaneous quantitation of tegafur (FT) and gimeracil (CDHP) in human plasma with a concentration range of 20-5000 and 2-500 ng/mL, respectively. Methanol was chosen as a precipitation agent for sample preparation. Chromatographic separation was performed on an inertsil ODS-3 C18 column using 1.0% formic acid in water and methanol (80/20, v/v) at a flow rate of 0.3 mL/min. The MS detection was operated with selected reaction monitoring (SRM) in the positive-ion mode. The matrix effect ranged from -8.9 to 7.8% for all analytes. The intra- and inter-day precisions were less than 8.6 and 9.5%, and the accuracy was within +/-7.5% for all analytes, respectively. The mean recoveries were 76.5 +/- 5.2 and 78.3 +/- 5.9% for FT and CDHP, respectively. The analytes were stable under all possible conditions of storing and handling for each compound. (+info)