Search results for "performance liquid chromatography"
showing 10 items of 649 documents
Identification and quantitation of methotrexate and methotrexate metabolites in clinical high-dose therapy by high pressure liquid chromatography and…
1982
High-pressure liquid chromatography in combination with field desorption mass spectrometry as techniques of high specificity and sensitivity have been applied to the identification and quantitation of the anticancer drug methotrexate and its metabolites which occur in clinical high-dose therapy. Field desorption mass spectra of methotrexate and several methotrexate and folic acid derivatives, when investigated as free acids or ammonium salts, yield abundant protonated molecular ions and a consistent pattern of structurally significant fragments. High-pressure liquid chromatographic separation of methotrexate metabolites was performed on reverse-phase, C-18 columns using a volatile, ammonium…
Automated Determination of Fluvoxamine in Plasma by Column-Switching High-Performance Liquid Chromatography
1992
Abstract A column-switching system with high-performance liquid-chromatographic separation and ultraviolet detection is described for automated determination of fluvoxamine in human plasma or serum. Samples were injected and the drug was retained in a clean-up column [20 x 4.6 mm (i.d.)] filled with C8 reversed-phase material (10-micron particles). After unwanted material was washed out, the drug was eluted and separated with an analytical chromatography column, 4.6 x 250 mm (i.d.), filled with Nucleosil 100 CN (5-micron particles) with an acetonitrile:methanol:0.01 mol/L phosphate buffer eluent (188:578:235 by vol) at a flow rate of 1.5 mL/min for < 20 min and detected by spectromet…
Automated Determination of Dextromethorphan and Its Main Metabolites in Human Plasma by High-Performance Liquid Chromatography and Column Switching
1996
An automated column-switching technique coupled to isocratic high-performance liquid chromatography (HPLC) with fluorescence detection was developed for simultaneous determination of dextromethorphan and its three major metabolites, dextrorphan, hydroxymorphinan, and methoxymorphinan. After cleavage of conjugates by incubation with glucuronidasearylsulfatase at 37 degrees C for 15 h, plasma samples were injected directly into the HPLC system. Dextromethorphan and metabolites were retained on a cleanup column (10 x 4.6 mm internal diameter [ID]) filled with cyanopropyl (CN) material (Hypersil CPS, 10-microns article size) while interfering proteins and lipids were washed to waste. After colu…
Doxepin and its metabolites in plasma and cerebrospinal fluid in depressed patients
1997
Little information exists on the concentrations of antidepressants and their metabolites in CSF. We measured plasma and CSF levels of trans-doxepin (trans-DOX) and DOX metabolites in 12 depressed patients treated with DOX (250 mg/day) for 6 days. Spinal taps and blood samples were taken on day 7, 10 h after drug administration. Trans-DOX, cis-desmethyldoxepin (cis-DM-DOX), trans-desmethyldoxepin (trans-DM-DOX) and di-desmethyldoxepin (DDM-DOX) were analyzed in CSF and plasma samples by HPLC with column-switching. Although DOX was given as a mixture of 85% trans-DOX and 15% of the pharmacologically more active cis-DOX, we found similar amounts of cis-DM-DOX and trans-DM-DOX in plasma (59.8 +…
Longitudinal analysis of taurine induced effects on the tear proteome of contact lens wearers and dry eye patients using a RP-RP-Capillary-HPLC-MALDI…
2012
Tear proteomic studies revealed distinct similarities between contact lens wearers and dry eye patients. AMO Complete® multipurpose contact lens cleaning solutions containing taurine seem to have a beneficial effect regarding contact lens induced dry eye. To illuminate the effect of taurine on the tear proteome of contact lens wearers and sicca patients we developed a gel-based RP-RP capillary HPLC-MALDI TOF/TOF MS strategy. Two contact lens wearer groups, one using eye drops containing 0.05% taurine; the other for control physiological NaCl solution were monitored. Also, a third group of sicca patients using taurine solution was studied (N=4 individuals/group). Tear pools of each group at …
Automated Determination of Ziprasidone by HPLC With Column Switching and Spectrophotometric Detection
2005
An isocratic high-performance liquid chromatography (HPLC) method with column switching and ultraviolet (UV) detection is described for quantitative analysis of the new antipsychotic drug ziprasidone. After centrifugation of serum or plasma samples and addition of fluperlapine as internal standard, the samples were injected into the HPLC system. On-line sample clean-up was conducted on a column (10 x 4.0 mm ID) filled with silica C8 material (20-microm particle size) using 8% (vol/vol) acetonitrile in deionized water as eluent. Ziprasidone was eluted and separated on ODS Hypersil C18 material (5 microm; column size 250 x 4.6 mm ID) using acetonitrile-water-tetramethylethylendiamine (50:49.6…
Evaluation of the plasmatic level of mepivacaine in different anatomical regions
2018
Background To evaluate the serum level of the local anesthetic mepivacaine 3% without vasoconstrictor in patients who underwent procedures performed in the anterior and posterior maxilla, through a method of possible extraction to quantify it in human plasma by high performance liquid chromatography (HPLC). Material and Methods This was a hybrid study consisting of 18 patients (7 females and 11 males) classified as ASA I, adults and with normal body mass index, submitted to procedures in the anterior region (group I) and posterior region of the maxilla (group II). For 40 minutes, five 6 ml blood samples were collected every 10 minutes after infiltrative injection in each region of the maxil…
Comparison of131I-metaiodobenzylguanidine scintigraphy with urinary and plasma catecholamine determinations in the diagnosis of pheochromocytoma
1985
In a retrospective study of 31 patients with suspected pheochromocytoma we examined the preoperative results of 131I-metaiodobenzylguanidine (131-I-MIBG) scintigraphy and a fluorimetric urine catecholamine determination test. An additional radioenzymatic plasma catecholamine determination test was performed in 25 patients. In 14 of the 31 patients the diagnosis of pheochromocytoma was later histologically confirmed. In the remaining 17 patients the suspected diagnosis was finally rejected after a clinical decision had been made on the basis of clinical history, symptoms, laboratory and imaging tests. 131-I-MIBG scintigraphy apparently had a very high specificity (no false-positive results a…
Enriched cereal bars are more effective in increasing plasma quercetin compared with quercetin from powder-filled hard capsules
2011
The flavonol quercetin, is one of the major flavonoids found in edible plants. The bioavailability of quercetin in humans may be influenced by the food matrix in which it is consumed as well as by its chemical and physical form. The objective of the present study was to investigate the biokinetics of quercetin from quercetin-enriched cereal bars and quercetin powder-filled hard capsules. In a randomised, single-blinded, diet-controlled cross-over study, six healthy women aged 22–28 years took a single oral dose of approximately 130 mg quercetin equivalents from either quercetin-enriched cereal bars (containing 93·3 % quercetin aglycone plus 6·7 % quercetin-4′-glucoside) or quercetin powder-…
Comparison of high-pressure liquid chromatography (HPLC) and Griess reagent-spectroscopic methods for the measurement of nitrate in serum from health…
2008
Bioavailability of NO can be estimated by measuring the concentration of nitrate (NO(3)) in serum. However, the methods used for the measurement NO(3) in plasma or serum show a great degree of variation. Therefore, we compared two analytical methods for the measurement of NO(3) in serum.The concentration of NO(3) in 600 serum samples collected from healthy individuals was determined by the HPLC and by the Griess reagent-spectroscopic method.The concentration of NO(3) in the samples was 29.4+/-16.1 micromol/L and 26.2+/-14.0 micromol/L (mean+/-SD) measured by HPLC and Griess reagent-spectroscopic method respectively (p0.0001). We detected a significant correlation between the two methods (R=…