Mn Analysis by Atomic Absorption

Introduction

Mn is present in the earth’s crust and in sea water at levels of about 0.09% and 0.002mg/L, respectively. Metallic Mn is obtained by reducing manganese ore using Al. The allotropes of Mn include α, β, γ and δ, among which the α and β allotropes are hard and fragile, the γ allotrope are ductile and the δ allotrope is stable only at high temperature. In the field of iron and steel, since manganese binds with sulfur in steel to alter the hardness of steel, it is an essential element in the production of steel withstanding strong impact and wear resistance. Since iron that contains Mn possesses great tensile strength, it is used in such parts as dredging buckets and caterpillars. Quadrivalent manganese dioxide, a typical Mn compound, is used as a desiccant and catalyst in the dye industry and as an iron decolorant as well as colorant in the glass industry. The powerful oxidant septivalent potassium permanganate is used for decoloration of bleach and oils and fats. Mn which is ingested by humans through food and drinking water is converted to Mn²⁺ by the action of gastric acid in the stomach, and is then oxidized to form Mn³⁺ in the intestinal tract where it enters the blood. In the blood, Mn³⁺, with characteristics similar to those of Fe³⁺, combines with the iron transport protein transferring to circulate and be carried to the various internal organs. More than 95% of the manganese is excreted in the bile via the liver. However, Mn acts to promote enzyme activity by combining with proteins and enzymes, playing a role in regulating their catalytic action. In addition, Mn can substitute for Ca and Mg, etc., thereby suppressing the action of these metals. Moreover, Mn has been found to lower blood sugar, and accordingly, is thought to promote activation of the insulin receptor. In general, there are few cases of manganese deficiency diseases, however, it is known that excessive consumption can result in its accumulation in the thyroid gland, causing enlargement of the gland. We introduce here the relationship between slit width and sensitivity in an analysis of manganese using flame analysis.

June 16, 2005 GMT