Plasma Sulfate Analysis: I. benzidine Method

Abstract

The quantitative determination of micro and ultra micro amounts of sulfate has historically been a problem to analytical chemists. The determination is further complicated if the analysis is to be performed on a complex solution where only a small amount is available. This is the situation one faces when attempting to analyze the quantity of sulfate in 50-200 ?l. of blood plasma. A literature search was made in order to evaluate the available methods, and to attempt to find an analysis that would work in the adverse conditions of blood plasma. . . . The most attractive method found was that of Lars Andersen of the University of Helsingfors, Finland.[8] Andersen suggests analysing for sulfate by precipitating it with benzidine, washing the precipitate thoroughly, redissolving it in acid solution, and measuring the ultraviolet absorption of the solution. Anderson reported result with an accuracy of 1-2%. He also points out that as reported earlier phosphate interferes with the analysis. . . . It is the aim of this project to re-test the reliability of the method and then attempt to apply it to small amounts of plasma samples. [From Introduction]