MICROCHEMICAL JOURNAL 39, 224-228 (1989) Manganese Determination by Electrothermal Atomic Absorption Spectrophotometry in Human Biological Tissues and Fluids J.R. CASTILLO' AND A. FERNANDEZ Department of Analytical Chemistry, University of Zaragoza, Zaragoza, Spain Received October 27, 1988; accepted November 17, 1988 Manganese was determined in human biological material by electrothermal atomic ab- sorption spectrophotometry. Before analysis, the samples were digested with HNO, and H,O, and the residue was dissolved in a solution of 1% (v/v) HNO,. The standard curve covers the range 0 to 1.6 ng with a coefftcient of variation of 2.84%. Optimum instrument operating parameters and the effect of foreign species are given. o 1989 Academic RCSS, I~C. INTRODUCTION The average human body contains between 10 and 20 mg of manganese, most of it accumulated in the cellular mitochondria and in the organs rich in cellular mitochondria, such as the brain, renal cortex, lung, testicles, and intestine. The daily requirement is between 2 and 5 mg. There are few references regard- ing deficiencies in man. Some individuals with low levels in serum have been found, normally with associated low levels of copper and zinc, producing alter- ations of the bone metabolism. Absorption is principally via the respiratory system. Manganese is rapidly as- similated by the liver, spleen, heart, and skeleton. The mechanism of storage in the body is not fully understood. The balance between intake and excretion is maintained mainly by absorption by the intestine and loss or excretion in feces, bile, and sweat. DNA and RNA synthesis is mediated by the enzymes DNA and RNA poly- merase, which contain zinc as an integral part of their structure, although they also require the presence of Mg(II), Mn(II), and Co(I1). Base pairing is three times more faithful in the presence of Mg(I1). The presence of Mn(I1) in the synthesis of DNA and RNA can lead to errors in replication and transcription. Manganese deficiency in man is related with delayed blood coagulation and hypercholesterolemia. It has been suggested that abnormal manganese metabo- lism can contribute to diabetes mellitus. Although excess manganese is a relatively rare phenomenon, investigation of it has led to further knowledge of brain metabolism and of neurological disorders. Chilean manganese miners, exposed to MnO, dust, develop severe neurological disorders similar to the symptoms of Parkinson’s disease (I). Manganese has recently been found to be related to heart disease (2). ’ To whom correspondence should be addressed. 224 0026-265X/89 $1.50 Copyright 0 1989 by Academic Press, Inc. All rights of reproduction in any form reserved.