Fluoremetry, quantitative analysis by comparative fluorescence. Preliminary report

UTHSC Affiliation

College of Medicine

Document Type

Article

Publication Date

7-1-1920

Publication Title

Journal of the American Chemical Society

Volume

42

Issue

7

Abstract

A new method of micro-analysis is described, of the same order of sensitiveness as colorimetry and nephelometry, which should prove generally applicable to the determination of minute quantities of the considerable number of substances which are either fluorescent themselves or may be rendered so by the addition of a suitable reagent. Ultra-violet rays from a quartz-enclosed mercury arc, filtered from most of the visible radiation, are used to excite fluorescence in solutions of such substances contained in the comparison cylinders of the Kober nephelometer. The intensity of the fluorescent light thus produced, as observed in the eye piece of the instrument, is equalized in the usual manner by altering the heights of the exposed columns. For sufficiently dilute solutions the curves obtained by plotting the scale readings against concentrations are quite regular. These calibration curves are drawn for solutions containing 0.5 to 2 mg. per liter of quinine sulfate in N sulfuric acid and for solutions of 2 to 4 mg. per liter of aniline iodeosine in 0.1 N alkali. Such a curve differs from that of inverse proportionality (the colorimetric curve) much more than from one drawn according to the nephelometric formula. Some peculiarities of the latter are indicated and it is shown that when 2 constants are used (one for solutions stronger than the standard and the other for those more dilute) the values corresponding to the fluoremetric readings may be taken from the nephelometric curve with an average error of less than 1%. It is expected that this can be reduced by the further elimination of errors in measurement or a further modification of the formula, or by both together. Various phases of the work, including certain applications, are receiving attention. © 1920, American Chemical Society. All rights reserved.

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