The Use of the Stuphenphotometer for Measuring Percentage Hemolysis.

Abstract

The methods for measuring percentage hemolysis may be divided into two classes, (1) subjective methods, such as those in which the observer adjusts the depth of a suspension until some object is just visible, or in which the hemolysing suspension is matched nephelometrically against standards, and (2) methods in which a photosensitive element, such as a potassium or selenium cell, a radiometer, or a thermopile, is used to measure the intensity of light transmitted by the suspension. The methods in the first group are unsatisfactory because too much depends on the judgment of the observer, and because rapid work is usually difficult or impossible; the photometers included in the second group, on the other hand, are usually unsatisfactory because of the difficulty in obtaining sensitivity and stability at the same time when the apparatus is so arranged as to make rapid consecutive readings possible. All methods, moreover, (except the radiometer method) are insensitive to changes in the range of 0% to 10% lysis. Ideally, the method used should be (a) capable of an accuracy of not less than ±2%, even in the range from 0% to 10% hemolysis, (b) sufficiently rapid to allow readings at intervals as short as 5 seconds, and (c) perfectly reliable in the sense that its performance does not depend on factors which require continual control. This last condition virtually rules out any method which is not entirely optical.

These conditions are met by the use of the “Stuphenphotometer” (“Stupho”), a photometer recently designed by Pulfrich of Carl Zeiss, in conjunction with a simple device for containing the cell suspensions whose opacity is to be measured. This consists of a large electrically heated and thermostatically controlled water-bath, one side of which is prolonged upwards as a screen, and pierced with two holes, 1.6 cm. in diameter, which exactly correspond to the 2 circular openings of the “Stupho” which faces them. (See Fig.)