ANALYTICAL TECHNIQUES AND QUALITY-CONTROL IN BIOMEDICAL TRACE-ELEMENT RESEARCH

The small number of analytical results in trace element research calls for special methods of quality control. It is shown that when the analytical methods are in statistical control, only small numbers of duplicate or replicate results are needed to ascertain the absence of systematic errors caused by sample contamination or interference from other elements. The distribution of determinations of Cu in chorion villi from normal pregnant women is used as an example, and after screening it proved to be closely approximated by a logarithmic normal distribution with a mean value of 0.6 mg/kg. Measurement compatibility is obtained by control of traceability to certified reference materials, (C) 1994 Wiley-Liss, Inc.