Analytical quality assurance studies for the microdetermination of Cr, Pb and Tl in human tissues

Abstract The knowledge of trace metal content in human tissues is essential: (i) for establishing normal criteria for metal concentration in population groups (ii) in the diagnosis of lung diseases (iii) for setting recommendations for airborne trace metal exposure. Unfortunately, much of the literature data on trace metals in humans is of questionable analytical quality. One of the reason is that little if any attention was given to contamination or loss during collection and handling of the samples before the instrumental analysis which can invalidate in practice also an excellent analytical quality of measurements. This work is part of a research activity on trace metals in humans carried out in the context of the Environmental Protection Programme at the JRC-Ispra. In particular, the following aspects are here considered: • (i) The study of some parameters affecting the microdetermination of Cr, Pb and Tl in human tissues such as sampling and sample pretreatment including the removal of organic matrix. The study is carried out by means of 51 Cr, 203 Pb and 201 Tl radiotracers. In particular, after administration of these radioisotopes to rats the radioisotopically-labelled tissues of the animals have been used for checking losses during freeze-drying, wet ashing by teflon-bomb and dry ashing processes. • (ii) The determination of Cr, Pb and Tl in human lung tissue. The analysis are carried out by radiochemical neutron activation analysis (RNAA), atomic spectrometry (AAS) and inductively coupled plasma (ICP). The use of special surgical titanium nitride-coated stainless steel instruments which minimizes the risk of trace metal contamination during sampling is also mentioned.