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At least 847 records · Page 47Linked to original sources
PubMed1987

A new method for the determination of saccharin based on thin-layer chromatography and spectrophotometry.

Saccharin is extracted from the acidified liquid food with chloroform. This solvent is evaporated; the residue is dissolved in ethyl acetate and applied on a silica gel GF254 plate. After chromatographic separation, the saccharin band is scraped off and extracted with 1% sodium carbonate solution. After centrifugation, absorbances at 235 and 244 nm are measured, and the difference A235-A244 is obtained. Standards similarly treated permit to get a calibrating plot and calculate the amount of saccharin in the sample. The method has good precision (C.V. 6%) and accuracy (91.2% recovery).

Chromatography, Thin Layer↗
PubMed1987

[Quantitative determination of the protein content of milk by ultraviolet spectrophotometry. 3. The protein content of whole milk].

It is possible to determine the protein content of unskimmed milk after dilution with a detergent solution by measuring of absorbance at 210 and 220 nm. If milk samples are not elder than 36 h the difference A210-A220 shows a high correlation to the values of Kjeldahl nitrogen analysis (r = 0.97). Similar coincidence was found to the values of absorbance measurements in skimmed milk (A210: r = 0.98; A235-A280: r = 0.96). With decreasing age of unskimmed milk samples the coincidence diminished. Absorbance data measured at 210, 215, 220, 225, 235 and 280 nm as well as the differences A215-A225 and A235-A280 do not much agree with analogous results from skimmed milk. Elderly creamed milk samples allow the determination of protein content from milk plasma. It could be proved by Kjeldahl nitrogen analysis, that differences in the nitrogen content of unskimmed and skimmed milk depend on the nitrogen-loss during centrifugation, on the protein content and the protein-fat-ratio.

Animals↗
PubMed1990

Effects of single-dose and short-term oral nifedipine on indocyanine green clearance as assessed by spectrophotometry and high performance liquid chromatography.

The effects of single-dose (10 mg) and short-term (10 mg tid) nifedipine treatment on apparent hepatic blood flow, as assessed by indocyanine green (ICG) clearance, were studied in ten healthy male subjects. ICG was measured by both spectrophotometric and high performance liquid chromatography (HPLC) assay methods. Blood clearance of ICG and apparent hepatic blood flow were increased by 30 and 50%, respectively, after single-dose nifedipine, whereas after 4 days' treatment these values were 12 and 30%. The spectrophotometric assay significantly overestimated ICG plasma concentrations from 7 minutes onwards. Although the spectrophotometric and HPLC assay showed marked differences in calculated half-lives and volume of distribution of ICG, the ICG clearance values were similar for the two assay methods.

Administration, Oral↗
PubMed1993

Use of reflectance spectrophotometry in the human corticosteroid skin blanching assay.

A reflectance spectrophotometric method for evaluation of the skin blanching response to topical corticosteroids was evaluated. This blanching response is used, for drug development and regulatory purposes, to assess potency and bioequivalence of topical corticosteroid products. The common method involves the use of a human rater to measure blanching response in the skin. This study evaluated an instrumental alternative to the human rater and used this method to measure the differences between a number of brand name and generic topical corticosteroid products (six creams and six ointments). Products were applied to the forearms of normal volunteers and the blanching responses were assessed after 6 and 16 hours in both occluded and non-occluded skin sites. Only the fluocinolone acetonide generic and brand name preparations were different from each other. The spectrophotometric method proved to be equivalent but not superior to the standard human observer method.

Administration, Topical↗
PubMed1987

The determination of Al, Cr, Co, Fe, and Ni in whole blood by electrothermal atomic absorption spectrophotometry.

Procedures for the determination of aluminum, chromium, cobalt, nickel, and iron in whole blood are presented and discussed. Chromium, cobalt, nickel, and iron were determined from one sample after decomposition of the blood with a mixture of nitric and perchloric acids. A graphite furnace was used for the determination of chromium, cobalt and nickel, and flame AAS was used for iron. The determination of Al was done from separate samples by GFAAS after dilution with 1% Triton TX-100. The normal concentration of these elements was measured in rabbit and dog blood.

Aluminum↗