Conventional Spectrophotometric Method Research Articles

New assay method for fatty acid synthetase with mass fragmentography.

A new assay method for fatty acid synthetase using mass fragmentography is described. The amounts of fatty acids synthesized in deuterated water are determined by mass fragmentography by monitoring the intensities of m/e 77 and m/e 74 fragment ions using heptadecanoic acid as an internal standard. This method is suitable for any fatty acid synthetase which produces several species of fatty acids and is also applicable to crude enzyme preparations. This procedure is more sensitive and specific than the conventional spectrophotometric method. Fatty acid synthetases from rat liver and Brevibacterium ammoniagenes are analyzed by this method.

ChemInform Abstract: CHEMOIMMUNOTHERAPY OF CANCER. 3. ANALYTICAL MEASUREMENT OF CHEMICAL HALF‐LIVES OF MONOFUNCTIONAL ALKYLATORS

AbstractFür die Stickstofflost‐Verbindungen (I) und (II) wird die Hydrolysengeschwindigkeit bestimmt.

Chemoimmunotherapy of cancer. 3. Analytical measurement of chemical half-lives of monofunctional alkylators.

The objective of this study is the measurement of the rates of hydrolysis of a series of chloroethyl sulfide derivatives, under stimulated physiological conditions. Interferences encountered with the conventional spectrophotometric method prompted the use of a rapid-response, chloride selective electrode. This probe was readily capable of monitoring the hydrolytic rate, which is identical with the rate of chloride ion formation. Since the desired subsecond half-lives were not achieved by any of the compounds, factors influencing the rates were investigated. The results suggest that the rate-controlling cyclization step may be inhibited, due to coordination of undissociated protonic functional groups on the aromatic portions of the structures with the lone-pair electrons on sulfur.

Absorption spectroscopy in scattering samples using integrated optics

Conventional spectrophotometric methods for measuring the concentration of light-absorbing material in a sample require that the sample be transparent. If scatterers are present they disturb the absorption measurement. An example of this sort is the determination of the constituents in blood plasma. Red blood cells interfere with a direct optical measurement if they are not removed. Theory and experimental results are presented for an integrated optics device which can perform absorption spectroscopic measurements of blood plasma with scatterers present. For a device which measured plasma bilirubin concentration, guided wave attentuation of less than 0.01 dB/cm due to red cell scattering was observed.

Interaction of organic dyes and proteins-determination of the binding constants spectrophotometrically

The spectral change of a small molecule (S) induced by addition of a large molecule (P) was examined theoretically and experimentally, assuming that the interaction betweenS andP follows theLangmuir adsorption isotherm. It was found that intermolecular binding constants could be determined accurately and conveniently by extrapolation to zero of two simple graphic relations, namely, the observed molar extinction coefficient ofS in the presence ofP versus the ratio of (the concentration ofS/the concentration ofP), and of the former versus the reciprocal value of the latter. This spectrophotometric method was applied to the binding of bovine serum albumin and Ponceau3 R and of bovine serum albumin and HABA at pH 7.0. The results obtained by this method were comparable with those obtained by equilibrium dialysis or by conventional spectrophotometric method.

Fluorescence of Barbiturates in Solution and Their Measurement in Pharmaceutical Preparations

Abstract The general utilization of fluorescence for pharmaceutical analysis is discussed and the native fluorescence of several barbiturates and the characteristics of each are reported. Concentration ranges applicable for linear response with the instrumentation used are also discussed. Utilization of direct measurement of the fluorescence of barbiturates for quantitative analysis provides simple, and thus faster, analysis with relatively the same accuracy and precision as conventional spectrophoto-metric methods. The wavelengths observed for emission and excitation make most analyses applicable to filter instrumentation. The simplicity of the analysis makes it generally applicable for automation.

Evaluation of a New Procedure for Measuring Serum Creatine Kinase Activity

Abstract A new spectrophotometric microtechnique for the determination of serum creatine kinase activity, in which all reagents are provided in a single com-pressed tablet, has been evaluated. The procedure depends upon coupling the creatine phosphate-ADP reaction with the hexokinase and glucose-6-phosphate dehydrogenase reactions. The new technique is quick, relatively simple, and gives results which compare favorably with the conventional spectrophotometric method in precision and sensitivity. It requires a sample volume of 10 Al, and values ranging from 10 to1600 U/liter can be determined without dilution. Gross hemolysis leads to erroneously high values, but the error is negligible with slightly hemolyzed specimens. A provisional normal range has been established

The extinction coefficient of human hemiglobincyanide

This chapter presents a discussion of spectrophotometry of hemoglobin and hemoglobin derivatives. Many special photometers (hemoglobinometers, oximeters, etc.) presently available for the determination of hemoglobin and hemoglobin derivatives are mentioned only incidentally. Numerous (spectro) photometric methods are developed for the determination of oxyhemoglobin, either as oxyhemoglobin fraction or as oxygen saturation. Many conventional two-wavelength spectrophotometric methods are available, most of them involving the use of an isobestic point in the absorption spectra of Hb and HbO2—for example, a wavelength at which the absorptivity of the two components has the same value. This yields a single, linear relationship between the oxygen saturation and the ratio of the light absorbances of the sample at the two wavelengths used. All methods for the spectrophotometric determination of hemoglobin derivatives depend on the validity of the Lambert-Beer law. Many two-wavelength methods are also used in the determination of common dyshemoglobins in human blood (HbCO, Hi, SHb). In all of these methods, the samples undergo some kind of pretreatment so that, besides the dyshemoglobin species to be determined, only one other hemoglobin derivative is present.

Application of Paper Chromatography and Electrophoresis to the Assay of Pharmaceutical Products

Results comparable to conventional colorimetric and spectrophotometric methods have been obtained by paper chromatographic and electrophoretic methods. In several instances, where stability studies are involved or when the combination of drugs do not lend themselves to assay by the usual methods, it is concluded that the chromatographic and/or electrophoretic procedures are a practical applicable solution. Some of the modifications that are needed for applying these chromatographic and electrophoretic methods to pharmaceutical assays are discussed. In general, separations of the various compounds are accomplished by ascending or descending paper partition chromatography, by selection of appropriate solvent systems, or by paper electrophoresis with selected pH buffer systems. The developed papergrams are sprayed with an appropriate color reagent and assayed quantitatively by photoelectric densitometry. The compounds treated in this manner are: phenylephrine hydrochloride, chlorpheniramine maleate, dextromethorphan hydrobromide, N-acetyl-p-aminophenol, meperidine hydrochloride, atropine, ethinyl estradiol, procaine and tetracaine hydrochlorides.