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At least 109 records · Page 6Linked to original sources
PubMed1989

Automated fluoroimmunoassay of theophylline and valproic acid by flow-injection analysis with use of HPLC instruments.

For automated determination of theophylline and valproic acid by use of Ames' fluoroimmunoassays we used a high-pressure liquid-chromatographic system consisting of a pump, a robotic unit (Gilson 231/401, to prepare and inject the samples into the flowing carrier), and a fluorometer with a 10-microL flow cell. Results correlated well with those of conventional liquid- and gas-chromatography (r less than 0.96). The between-run CV is about 5%. In comparison with the manual method, the volume of reagents (and thus the cost per analysis) was decreased by eightfold.

Autoanalysis↗
PubMed1990

A flow injection analysis system involving immobilized NADH oxidase in column form for clinical analysis.

A highly sensitive FIA system for chemiluminometric determination of reduced coenzyme, NADH, was developed, using immobilized NADH oxidase from Brevibacterium ammoniagenes. The enzyme catalyzed the oxidation of NADH generating hydrogen peroxide which emitted chemiluminescence when mixed with luminol and potassium ferricyanide. The immobilized enzyme reactor was a mini-column, measuring 1 or 2 mm in inner diameter and 20 mm in length, and the sample volume was only 1 microliter per assay, with a feeding speed of one sample per min and a lowest detection limit of 10 pmol NADH. A FIA system was also developed for the determination of magnesium in human serum, using an enzyme column reactor with simultaneously coimmobilized hexokinase, D-glucose-6-phosphate dehydrogenase, and NADH oxidase. The performance of the system was as satisfactory as a routine colorimetric assay, but with much higher sensitivity.

Colorimetry↗
PubMed1989

Rapid-scan hydrodynamic voltammetry and cyclic voltammetry of pharmaceuticals in flow injection analysis conditions.

An on-line rapid-scan electrochemical detector is described for HPLC and FIA systems. Its practical use in qualitative analysis is demonstrated for 19 drug substances. The detector can be operated to record convection/diffusion-controlled (S-shaped), or diffusion-controlled (peak-shaped) voltammograms. In the latter mode, on-line cyclic voltammetry measurements are possible. The cell can also be used as an amperometric detector for conventional, microbore and micro-LC methods. Detection limits are of the order of 10 pg (conventional and microbore HPLC), or at the sub-picogram level (micro-LC). For scanning work, drugs can be analysed at mg l-1 levels in an FIA setup.

Caffeic Acids↗
PubMed1988

Chromatography, flow injection analysis and electrophoresis in computer-assisted comparative biochemistry: its application and possibilities in clinical research. Preliminary studies on Crohn's disease.

A computer-assisted multicomponent analytical system, developed for comparative biochemical studies, was used for a clinical study of Crohn's disease in which 73 subjects, of comparable age and sex distribution, were considered: 40 with Crohn's disease, 16 with ulcerative colitis and 17 healthy volunteers as controls. Blood samples (5 ml) were taken to recover plasma and red cells. After extraction and fractionation of low- and high-molecular weight substances, the samples were analysed by ion-exchange chromatography and electrophoresis. The contents of amino acids, sugars, polyamines and proteins in the plasma and the red cells from the three groups of individuals were compared using statistical (means, variance, principal components analysis) and graphical profile methods. The first results indicate that the content of red cells, in comparison with plasma, allows the best differentiation of the three groups of subjects considered. In particular, the amino acids (Asp, Thr, Ser, Glu, Gly, Ala and Leu), the polyamines (spermidine and spermine) and glucose, show the most significant differences. The methodology followed and the results obtained, together with possible uses of this computer-assisted multicomponent analytical system in problems concerning clinical research, are discussed.

Adult↗