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A simple and reliable method for the evaluation of the extrinsic coagulation pathway is presented. The method is based on the monitoring of the last step of the coagulation pathway in which the human plasma is clotted by the presence of the coagulations factors (prothrombin, factor V, factor X, calcium and phospholipids) in an excess of thromboplastin. It has been developed using a flow injection...
A direct spectrophotometric procedure for the determination of theophylline in plasma is proposed. This procedure is based on the apparent content curves method and it is not necessary to know the nature and contents of interferent substances. Bias errors introduced by plasma and metabolites are avoided. The results obtained are in agreement with those provided by an immunofluoroassay used as a...
A pretreatment method based on borate complex formation is described for the selective and simultaneous quantitation of pharmacologically active catechins in human plasma and saliva. This method is based on the interaction of catechins with diphenylborate (as a complexing agent) and tetra-n-butylammonium (as a counter ion) in alkaline media to give the catechin-diphenylborate complex and ion-pair...
The micellar electrokinetic capillary chromatography (MECC) method is reported for the separation of heparin, and for the possibility of direct determination of free heparin in plasma. The conditions for MECC were: pH 8.5, 25 mM sodium dodecyl sulfate (SDS), 25 mM borate buffer, with a 30 cm 50 μm ID fused-silica capillary. The sample was detected with a UV-detector at 270 nm with heparin as external...
A solid-phase extraction (SPE) method for sample clean-up followed by a reversed-phase high-performance liquid chromatography (HPLC) procedure for the assay of five antidepressant drugs (trazodone, doxepin, desipramine, maprotiline and imipramine) is reported. The drugs were recovered from plasma buffered at a suitable pH using C18 Bond-Elut cartridges and mixtures of methanol-aqueous buffer as washing...
Homocysteine present in human blood plasma is derivatized with thiol selective ultraviolet labelling reagent, 2-chloro-1-methylpyridinium iodide, and separated from other plasma thiol derivatives by high-performance liquid chromatography (HPLC) with detection at 312 nm. The separation is carried out isocratically on LiChrospher RP-18 column using mobile phase consisting of pH 2.5 0.04 M trichloroacetic...
This paper describes the development and validation of a reversed-phase HPLC method with isocratic conditions for the analysis of total cysteine in human plasma. The essential steps in the assay include derivatization of cysteine via thiol group with 2-chloro-1-methylpyridinium iodide (CMPI), separation of the formed cysteine S-pyridinium derivative from endogenous thiol derivatives, usually present...
A column-switching HPLC method was described for the direct analysis of clarithromycin in human plasma using electrochemical detector without sample pre-purification step. Plasma samples were diluted with washing solvent, i.e. acetonirile–methanol–0.05 M potassium phosphate buffer (pH 7.0) (5:2:93, v/v) and then, injected to the precolumn. After plasma proteins had flowed out from the precolumn, clarithromycin...
All aerobic organisms have developed different mechanisms for neutralising the free radicals, mostly produced by the monoelectronic reduction of O 2 , and preventing the severe damages these can provoke. The efficiency of these mechanisms can be assessed, in different matrices, by a simple and direct chemiluminescent assay (CL) based on luminol oxidation catalysed by horseradish peroxidase...
A sensitive differential pulse anodic stripping voltammetric method is described for the determination of alendronate sodium, desferrioxamine mesylate and lisinopril. The procedure is based on the formation of labile drug-copper(II) complex when shaking with copper(II) phosphate suspension. The voltammetric peaks, which correspond to the reduction of the copper(II) moiety of the formed complexes are...
A multiwall carbon nanotubes (MWNTs) film modified electrode was prepared and used as an amperometric sensor for the simultaneous determination of oxidizable amino acids including cysteine, tryptophane and tyrosine. The electrochemical behaviors of these amino acids at this modified electrode were studied by cyclic voltammetry (CV). The results indicated that the MWNTs chemically modified electrode...
Carbamazepine (CBZ) and phenytoin (PHT) are two antiepileptic drugs which are used simultaneously. In this paper a partial least-squares (PLS) calibration method is described for the simultaneous spectrophotometric determination of CBZ and PHT in plasma. Standard binary mixtures of CBZ and PHT have been resolved by application of PLS-1 to their UV spectra. Then, the binary standard solutions, spiked...
A rapid and sensitive high-performance liquid chromatographic method has been developed for the simultaneous determination of the antidepressant fluoxetine and its active metabolite norfluoxetine in human plasma using paroxetine as internal standard. After liquid–liquid extraction, the compounds were separated on a C18 column using as mobile phase acetonitrile and 40mM potassium dihydrogen phosphate...
Four glutathione (GSH)-selective electrodes were developed with different techniques and in different polymeric matrices. Precipitation-based technique with bathophenanthroline–ferrous as cationic exchanger in polyvinyl chloride (PVC) matrix was used for sensor 1 fabrication. β-Cyclodextrin (β-CD)-based technique with either tetrakis(4-chlorophenyl)borate (TpClPB) or bathophenanthroline–ferrous as...
Fluoroquinolones or so-called second-generation quinolones, in particular, ofloxacin (OFL), norfloxacin (NOR), and enoxacin (ENO), with therapeutic advantages possess strongly overlapped fluorescence spectra. In this paper, two strategies were proposed for simultaneous direct determination of OFL, NOR and ENO in plasma by combining fluorescence excitation–emission matrix (EEM) with second-order calibration...
A sensitive and specific high-performance liquid chromatography (HPLC) method has been developed and validated for the quantification of mexiletine (MEX) in human plasma and urine. It uses solid-phase extraction (SPE) followed by an automated reversed-phase HPLC with a pre-column derivatization with 4-chloro-7-nitrobenzofurazan (NBD-CI) and UV–vis Absorbance detection. The process was set as: the...
The high-performance liquid chromatography (HPLC) coupled with on-line solid phase extraction (SPE) and ultraviolet (UV) detection was developed for determining andrographolide and dehydroandrographolide in rabbit plasma. Plasma samples (100μL) were injected directly into a C18 SPE column and the biological matrix was washed out for 6min using 15% aqueous methanol. By rotation of the switching valve,...
A rapid and specific HPLC method was developed and validated for simultaneous determination of diazepam and its main active metabolites, desmethyldiazepam, oxazepam and temazepam in human plasma. Plasma samples were extracted using toluene. HPLC system included a Chromolith™ Performance RP-18e 100mm×4.6mm column, using 10mM phosphate buffer (pH 2.5)–methanol–acetonitrile (63:10:27, v/v) as mobile...
A new, simple, sensitive and specific reversed-phase high performance liquid chromatographic (HPLC) method using ultraviolet detection was developed and validated for the analysis of CPT-11 (λ max =254nm, 365nm) and its major active metabolite, SN-38 (λ max =380nm) in rat plasma and bile. The sample pre-treatment from plasma involved a single protein precipitation step with cold acetonitrile...
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