Author(s): Mahmoud Badran, Azizah Ismail, Reda Morsy and Tarek Elnimr*
The metals Al, As, B, Br, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Ru, Sn, V and Zn and the non-metal Se are considered ‘‘trace elements’’(TE) because of their essentiality and very limited quantity in humans. Therefore, this study aims to understand the heavy metal contents in human biological materials, using different digestion methods and to recommend the most appropriate digestion method making this measurement. Three reference materials from different sources were selected to be digested by five methods to determine the contents of these trace elements by ICP-MS. The five digestion methods were nitric acid, nitric acid - hydrogen peroxide, nitric - sulfuric acid, nitric–perchloric acid and sulfuric acid methods. Analytical results indicated that the nitric acid procedure was the most efficient for recovering Br, Ca, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn from most certified reference materials. The sulfuric acid procedure yielded the lowest recovery of Pb from the certified reference material. The nitric acid procedure was recommended as the method for digesting the human biological materials samples herein, based on recovery analysis, cost and time taken. Nitric–perchloric acid procedure was not recommended because perchloric acid is potentially hazardous during digestion and it recovers relatively little heavy metal.