A simple micromethod for the determination of lead in small amounts of blood.

In lead poisoning the determination of the concentration of lead in the blood is a useful aid in diagnosis and also in the supervision of treatment. For clinical purposes, an extremely accurate result is not necessary. It may be much more important to learn quickly that the lead content of the blood is within a certain significant range of values than to learn much later the value correct to 0 001 mg. per 100 g. of blood. The advantages of the method to be described are: (1) The amount of blood required is only 0 5 ml., which can be obtained by finger prick. (2) No expensive apparatus is required. (3) All the manipulations are carried out in the one vessel. (4) A single determination can be done in two hours, or five in three hours with six flasks. Briefly the method is to carry out wet oxidation of the organic matter in the blood, and then to determine the lead by the mixed-colour dithizone method. Fischer (1929, 1934), and Fischer and Leopoldi (1934) have described very fully the properties of dithizone and of the compounds formed by it with a large number of metallic elements. Many investigators have used dithizone for the determination of lead in biological and other materials, and the advantages of the mixed colour method for the determination of lead in various substances have been shown by Clifford and Wichmann (1936), Harrold, Meek, and Holden (1936), Hubbard (1937), Shiels (1938), and Bambach (1939, 1940). Nothing new is claimed in this method, except its application to determining lead in very small amounts of blood. Spectrographic and polarographic methods for the determination of lead in a drop or so of blood have been described previously but the apparatus required is expensive, or not so suitable for the simultaneous determination of a number of samples. The present method requires a considerable amount of manipulative skill but no costly apparatus.