Spectrophotometric characteristics and assay of pure pyronin Y
SummaryThe spectrophotometric characteristics of analytically pure pyronin Y have been investigated. Addition of metal ions (Fe3+, Zn2+, and Mg2+) and of dextrin were shown not to influence the absorption characteristics. The composition of the solvent strongly influenced the value of the extinction coefficient. Aqueous ethanolic solutions with a content of about 50% ethanol gave higher ε-values than those found for more concentrated ethanol solutions. The difference can be explained by the existence of a solvent-solute complex in the less concentrated ethanol solutions. A new spectrophotometric assay is proposed using the ε-value 11.7×104 lmol−1 cm−1 found in aqueous ethanol (52%) as standard.
The Analysis of Neutral Red and of the Pyronins
Neutral red and the pyronins cannot be evaluated by means of reduction with titanous chloride, and market supplies of the stains contain nitrogenous dye intermediates which render other chemical methods of determining dye content unreliable.Data are furnished in the present paper which will enable the analyst to obtain reliable dye-content values with samples of these dyes by means of a convenient spectrophotometric technic.
Solidarity. Reflections on an Emerging Concept in Bioethics. Summary
1. References to solidarity are currently on the increase in public discourse. In the UK and beyond, during economic crises and in a political climate where many feel that mutual assistance has lost currency, calls for a new and forceful emphasis on the meaning of solidarity are increasingly heard. Such appeals to solidarity are inevitably linked to ideas about how societies function, and about how and where the boundary between individual, familial, communal and societal spheres of responsibilities should be drawn.