Search results for " High pressure liquid"
showing 10 items of 705 documents
Comparison of different sorbents for on-line liquid-solid extraction followed by high-performance liquid chromatographic determination of nitrogen-co…
1998
Abstract LiChrolut EN [poly(styrene-divinylbenzene), PSDVB], Carbograph (graphitized carbon black, GCB), Isolute CN (cyanopropylsilica), Isolute C 2 (ethylsilica), and LiChrospher RP18 (octadecylsilica) were studied for on-line solid-phase extraction of twelve nitrogen containing pesticides from water. Determination (UV 210 nm) was performed with a Spherisorb C 8 analytical column and an acetonitrile-water gradient. The mean recoveries from 50 ml ranged from 83% for RP18 to 44% for GCB, and decreased in the following order: RP18, CN, LiChrolut EN, C 2 , and GCB. GCB showed poor recoveries due to incomplete desorption with the acetonitrile-water gradient used, and memory effects were detecte…
A bioluminescence technique for quantitative and structure-associated imaging of pyruvate
2006
A novel bioluminescence assay has been developed for measuring pyruvate within sections of snap-frozen tissue in a quantitative manner as well as with a spatial resolution on a microscopical level. The assay was verified via HPLC and two independent photometric tests. The novel assay makes it possible to determine pyruvate concentrations in cryosections in the range of 0-5.0 micromol/g tissue (dry weight). Based on the analysis of samples of given pyruvate concentrations, the assay exhibits a recovery with a deviationor =15%. The minimal detectable amount was 0.02 pmol based on a 20 microm thick tissue section with an area of 1 cm(2). Combination of the already established imaging biolumine…
Sensitive determination of aliphatic amines in water by high-performance liquid chromatography with chemiluminescence detection.
2004
A sensitive method has been developed for liquid chromatographic determination of short aliphatic amines in water samples. Analytes are preconcentrated and dansylated on solid sorbents (C18 solid-phase extraction cartridges). The dansyl derivatives are chromatographed and post-column mixed with peroxyoxalate (TCPO) and H2O2 in order to perform chemiluminescence detection. Optimal results have been obtained using a sample volume of 5 ml. The method has been applied to the quantification or screening of several aliphatic amines: methylamine, ethylamine, butylamine, diethylamine, pentylamine and hexylamine. The screening procedure has been developed including also polyamines (putrescine, cadav…
Induction of digoxin-like material production, and the digoxin binding in the unicellular organism Tetrahymena by digitoxin.
1998
Thin layer chromatographic, and laser-confocal microscopic analyses with a monoclonal antibody to digoxin also displaying high affinity to digoxigenin, were used to determine the presence and localization of cardioactive glycosides. Tetrahymena pyriformis was found to possess digitoxigenin-like material, but digoxin, digitoxin, digoxigenin, gitoxin and lanatoside C were not detected. Digitoxin treatment elicited the appearance of a digoxin-like material in the progeny generations. Digoxin was taken up by untreated Tetrahymena, especially strongly 24 h after digitoxin treatment. While the cardenolide was localized in vesicles of the cell body in untreated Tetrahymena, the engulfed digoxin ap…
Column-switching techniques for screening of diuretics and probenecid in urine samples
1994
A method based on high-performance liquid chromatography using column-switching is described for the screening of diuretics and probenecid in urine samples. The system uses a 20- x 2.1-mm i.d. precolumn, packed with a Hypersil ODS-C18, 30-microns stationary phase, for the on-line sample cleanup and enrichment. Untreated urine samples are directly injected, and the precolumn is flushed for 1 min with water to eliminate polar matrix components. The retained analytes are then back-flushed by means of a six-port switching valve onto a Hypersil ODS-C18 analytical column (5 microns, 250- x 4-mm i.d.), where they are separated using an acetonitrile/phosphate buffer (pH = 3) gradient elution. Under…
Loading profile of topotecan into polyvinyl alcohol microspheres (DC Bead™) over a 7-day period
2011
Purpose: DC Bead™ is successfully used for chemoembolization of various liver cancers. The purpose of this study was todetermine the loading capacity of the semi-synthetic topoisomerase-1 inhibitor topotecan into the DC Bead™ microspheres under static or agitated conditions and to assess the physicochemical stability over a period of 7 days. Methods: Commercially available topotecan hydrochloride powder (Hycamtin®) was reconstituted with water for injection to yield a nominal concentration of 1 mg/mL topotecan. Polyvinyl alcohol (PVA)-based microspheres (DC Bead™, 300–500 µm, 2 mL/vial) were mixed with 4 mL of the reconstituted topotecan solution. Vials were stored light protected at room …
Loading, release and stability of epirubicin-loaded drug-eluting beads.
2015
Purpose The aim of this study was to determine the loading efficiency, physico-chemical stability and release of epirubicin-loaded DC Bead™ (Biocompatibles UK Ltd, a BTG International group company) (bead size 70–150 µm (=DC Bead M1™) and 100–300 µm) after loading with epirubicin solution (2 mg/ml) or reconstituted powder formulation (25 mg/ml) and controlled storage. Methods DC Bead™ were loaded with 76 mg epirubicin solution (Epimedac™, Medac GmbH) or 75 mg epirubicin powder formulation (Farmorubicin™, Pharmacia Pfizer GmbH) per 2 ml of beads. Drug loading efficiency and stability were determined by measuring the epirubicin concentration in the excess solution after predetermined interval…
Stability of tacrolimus ophthalmic solution
2017
Purpose The stability of 0.3-mg/mL tacrolimus ophthalmic solution at different storage temperatures was studied. Methods A sterile ophthalmic solution of 0.3 mg/mL tacrolimus was prepared in triplicate under aseptic conditions by diluting tacrolimus in eye drops. Three aliquots of this solution were transferred into polypropylene bottles and stored at 25, 2–8, or −15 to −25 °C. Samples were collected immediately after preparation and at selected time points and assayed in triplicate using high-performance liquid chromatography (HPLC). Samples were also visually examined for macroscopic changes. The 0.3-mg/mL tacrolimus solution was also exposed to acidic treatment and heat to force its degr…
Duloxetine serum concentrations and clinical effects. Data from a therapeutic drug monitoring (TDM) survey.
2009
INTRODUCTION The aim of this study was to relate drug concentrations in serum and clinical effects in patients treated with the new antidepressant duloxetine. METHODS Data were obtained from a newly established therapeutic drug monitoring (TDM) survey. Duloxetine was measured using HPLC with UV detection and clinical effects by the clinical global impressions (CGI) scale for improvement. RESULTS The study included 103 depressed inpatients (69% female). Patients under duloxetine monotherapy who were very much improved according to CGI had significantly (p<0.05) higher serum levels than patients with moderate, minimal or lacking improvement (mean+/-SD and range, 93+/-53 ng/mL and 30-182 ng/mL…
Micellar electrokinetic capillary chromatography for therapeutic drug monitoring of carbamazepine and its main metabolites.
1998
In carbamazepine (CBZ) therapy the concomitant monitoring of concentrations of CBZ and its metabolites is strictly recommended, primarily to avoid toxic side effects. Currently, clinical routine monitoring of CBZ is accomplished by high-performance liquid chromatography or immunological methods. In this study a micellar electrokinetic capillary chromatographic (MECC) method was developed for routine drug monitoring of CBZ and its main metabolites, carbamazepine 10,11-diol and carbamazepine 10,11-epoxide, in human serum or plasma samples. The MECC method enabled baseline separation of all analytes within 2.5 min. The assay revealed sufficient precision and sensitivity and the results of eith…