Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.1.6 (CAD)
 4,420 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A simple, specific, and high throughput liquid chromatography tandem mass spectrometry method is developed for the determination of tenofovir, a nucleotide reverse transcriptase inhibitor, in human plasma using adefovir as internal standard. Plasma samples are prepared by solid-phase extraction of the analyte and internal standard using Waters Oasis MCX cartridges (1 cc, 30 mg). The chromatographic separation is achieved on a reversed-phase Chromolith, C18 analytical column (100 mmx4.6 mm, 5 microm) under isocratic conditions. The mobile phase consists of 0.5% formic acid in water and acetonitrile (90:10, v/v) to give a run time of 1.8 min. The protonated precursor-->product ion transitions for tenofovir and IS are monitored on a triple quadrupole mass spectrometer, operating in the multiple reaction monitoring and positive ion mode. The fragmentation pathways for tenofovir are studied by varying the collision energy (5-55 V) using nitrogen as CAD gas. A linear dynamic range of 3.1-1002.0 ng/mL is established using 0.2 mL plasma sample. The method is fully validated for its sensitivity, selectivity, accuracy and precision, matrix effect, recovery, stability, and dilution integrity. It is applied to a bioequivalence study in 43 human subjects after oral administration of 300 mg tablet formulation under fasting conditions.
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PMID:Rapid and specific liquid chromatographic tandem mass spectrometric determination of tenofovir in human plasma and its fragmentation study. 1922 22

CAD (charged aerosol detector) has recently become a new alternative detection system in HPLC. This detection approach was applied in a new HPLC method for the determination of three of the major statins used in clinical treatment-simvastatin, lovastatin and atorvastatin. The method was optimized and the influence of individual parameters on CAD response and sensitivity was carefully studied. Chromatography was performed on a Zorbax Eclipse XDB C18 (4.6 mm x 75 mm, 3.5 microm), using acetonitrile and formic acid 0.1% as mobile phase. The detection was performed using both CAD (20 pA range) and DAD (diode array detector-238 nm) simultaneously connected in series. In terms of linearity, precision and accuracy, the method was validated using tablets containing atorvastatin and simvastatin. The CAD is designated to be a non-linear detector in a wide dynamic range, however, in this application and in the tested concentration range its response was found to be perfectly linear. The limits of quantitation (0.1 microg/ml) were found to be two times lower than those of UV detection.
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PMID:Comparison of UV and charged aerosol detection approach in pharmaceutical analysis of statins. 1926 37

The goal of this work was to establish a simple HPLC-ESI-ITMS/MS procedure, suitable for the determination of four common aliphatic polyamines in two different types of biological matrices. To this end, 1,6-diaminohexane was used as the internal standard (IS) and 4-fluoro-3-nitrobenzenotrifluoride (FNBT) as the derivatizing agent. Formation of fully derivatized compounds was confirmed by high resolution ESI-QTOFMS and MS/MS analysis. Reversed phase chromatographic separation was carried out by gradient elution with 0.1% (v/v) formic acid and methanol. In a positive ESI mode, the following pairs of precursor/quantifier ions were used for multiple reaction monitoring: 467.4/261.0 for PUT, 481.2/461.1 for CAD, 713.7/261.0 for SPD, 959.8/507.2 for SPM and 495.3/475.2 for IS. On-column instrumental detection limits of four polyamines were in the range 0.62-2.14fmol (0.039-0.215ng/ml). Versatility was demonstrated by analyzing plant extracts and human urine; prior to derivatization, all samples were cleaned-up by dichloromethane extraction. The evaluated signal suppression/enhancement was in the range 82.3-115.4% and the percentage recoveries obtained in the method of standard addition were in the range 83.7-114.4%. Statistically significant differences in polyamines concentrations were found in garden cress exposed to Cd(II) versus control seedlings (t-test, p<0.05); results obtained for urine from healthy volunteers and diabetic patients at different clinical conditions suggested possible utility of free polyamines as biomarkers of progressive diabetes.
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PMID:Determination of putrescine, cadaverine, spermidine and spermine in different chemical matrices by high performance liquid chromatography-electrospray ionization-ion trap tandem mass spectrometry (HPLC-ESI-ITMS/MS). 2634 Jul 61