Biomedical subjects

G Anders

Publications and source records attributed to G Anders.

At least 55 records · Page 3Linked to original sources

PubMed1975

Bleed fastness of fluorescent whitening agents in mass whitened paper.

Paper samples mass whitened with fluorescent whiteing agents (FWAs) of three different types (di-, tetra-, and hexasulfonated derivatives of 4,4'-diaminostilbene-2,2'-disulfonic acid) were examined for bleed fastness in five different eluents. Fluorescece intensity was measured by a sensitive spectrofluorimetric technique instead of the usual visual assessment. The degree of bleed obtained from each of the FWAs tested was less than 0.4mg/600 cm2 of paper surface area. The FWAs were applied at a normal concentration of use i.e. 0.05% active substance. FWAs with a high degree of sulfonation tend to bleed in aqueous solvents, and those with a lower degree of sulfonation in alcohol solutions. In aqueous acid solutions the degree of bleed was very low in all cases (0.04 mg/600 cm2 of paper surface area). In fatty solutions there was no bleed at all. The limit of detection was 3mug/600 cm2 of paper surface area, with an accuracy of +/-15%.

Coloring Agents↗

PubMed1975

Analysis of river water and drinking water from seven European countries.

During the months of June to August and September to December 1972 and again from January to April 1973, the river and drinking water at a number of points in seven European countries was examined for fluorescent content. The purpose of the river water studies was to identify any traces of fluorescent whitening agents (FWAs) and relate them as far as possible to knolementary role and also helped to interpret the scatter of the control level of the river water studies. Identification and separation were carried out by means of a combination of spectrofluorimetry and thin layer chromatography. Detection limits and reproducibility of the methods of determination are explained in the chapters V/3-7 (methods of analysis for FWAs. The second river water survey showed that at only one sampling point (Borås in Sweden) there was detectable concentrations (up to 8 ppb) of a lipophilic unsulfonated FWA [2, 5-BIS (BENZOXAZOL-2-YL)THIOPHENE], And these were still about 1 ppb in the third survey. JENSEN and co-worker had previously detected this substance at the same location. No traces of FWAs were detected in any of the other tests. The detection limit in river water was 0.01 ppb (1 part per American billion = 10(-3) gram per metric ton). For identification purposes, a test mixture of six FWAs each with a different chemical constitution and different fields of application was used, and this was first exposed to light in an aqueous solution for some minutes.

Chromatography, Thin Layer↗

PubMed1975

Measurement of fluorescent white effects and whiteness.

This report surveys the literature and describes various techniques of whiteness measurement and evaluation in current use. Measuring techniques are described for dealing separately with the effects obtained by bleaching, blueing and fluorescent whitening, and an example is given of the direct quantitative estimation of a fluorescent whitening agents (FWAs) on a substrate by measuring reflectance in the ultraviolet region. Another chapter deals with the colorimetric estimation of the whiteness and the shade of a fluorescent white using modern apparatus in conjunction with a programmable minicomputer. A new simple and universally applicab,e formula was worked out: W=D-Y+P-x+Q-y+C which has been successfully used in routine tests and which for the first time gives different weight to whiteness values corresponding to all shade preferences existing in theory. Each user can match the formula to his own preference by appropriate adjustment of the D, P, Q andC values. Y,x and y are the customary colorimetric values as standardized by the CIE (Commission Internationale de l'Eclairage). It was also found that with another formula the shades of fluorescent whitening effects (green to red tints) may be defined in a simple way.

Color↗

PubMed1974