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Biomedical subjects

G D Christian

Publications and source records attributed to G D Christian.

At least 55 records · Page 3Linked to original sources
PubMed1976

Multicomponent analysis in clinical chemistry by use of rapid scanning fluorescence spectroscopy.

To be useful in the clinical laboratory, multicomponent fluorescence analysis requires both the rapid measurement of the fluorescence intensity at a variety of excitation and emission wavelengths and the unambiguous reduction of the data by efficient algorithms. The Video Fluorometer, which exploits the multi-channel capability of a low-light-level television sensor to simultaneously acquire excitation and emission spectra, can meet the first requirement. For example, a complete set of emission and excitation spectra for perylene can be obtained in less than 2 s at concentrations of 10(-10) mol/liter. To meet the second need, we present two types of data-reduction strategies: (a)a least-squares fit to the data, with use of the spectra of previously determined compounds likely to be present; and (b)a determination of the eigenvalues and eigenvectors fo the fluorescence matrix, from which the number of components and the possible spectra of each can be estimated. Computer simulations of the least-squares fitting algorithms show that five strongly overlapping components can be determined in the presence of noise with an accuracy of better than 5%. Also, a fluorescent sample containing two species with very similar but unknown spectral properties can be resolved to obtain the spectrum of each.

Anthracenes↗
PubMed1975

Assay of L-tyrosine in serum by amperometric measurement of tyrosinase-catalyzed oxygen consumption.

A new enzymatic method for rapid direct measurement of serum tyrosine is described, based on the amperometric measurement of the rate of oxygen consumption when tyrosine is oxidized in the presence of the enzyme tyrosinase in a phosphate buffer (0.1 mol/liter, pH 7.4). A Beckman Glucose Analyzer with a Clark electrode is used for the measurement. The procedure does not require removal of serum protein, incubation nor extraction, and results are obtained in less than 1 min. Results agree closely with those obtained by a fluorometric procedure and with an amino acid analyzer.

Adult↗
PubMedDate not supplied

Novel flow injection analysis systems for drug analysis.

Flow injection analysis (FIA) has become a versatile tool for rapid and automated analyses. As its capabilities have increased, so have the complexity and operation of the apparatus. We have been investigating ways to simplify both the apparatus and the application of injection techniques. A novel cam-driven syringe pump and the development of sequential injection analysis (SIA) are reviewed, and some applications presented. Flow injection coulometric titrations are presented as a means to further alleviate reagent stability and calibration problems. These systems have potential for automatically carrying out many drug assays.

Calibration↗