Cooperative interlaboratory surveys of the determination of cadmium in whole blood

Sample collection guidelines for trace elements in blood and urine. IUPAC Commission of Toxicology

This paper presents an organized system for element-specific sample collection and handling of human blood (whole blood, serum or plasma, packed cells or erythrocytes) and urine also indicating a proper definition of the subject and sample. Harmonized procedures for collection, preparation, analysis and quality control are suggested. The aim is to assist scientists worldwide to produce comparable data which will be useful on a regional, national and international scale. The guidelines are directed to the elements aluminium, arsenic, cadmium, chromium, cobalt, copper, lead, lithium, manganese, mercury, nickel, selenium and zinc. These include the most important elements measured for their occupational or clinical significance, and serve as examples of principles that will guide development of methods for other elements in the future.

Danish external quality assessment scheme: an interlaboratory comparison study on lead, cadmium and chromium in lyophilized human blood concentrate

A Danish External Quality Assessment Scheme (EQAS) was carried out by the Danish National Institute of Occupational Health during the period 1988-1992. The scheme was implemented for 29 international laboratories from 15 countries assaying lead, cadmium, and chromium in human blood to ascertain the systematic error and uncertainty of the analytical methods. In the survey the quality control material AMI B701-B705, based on lyophilized human whole-blood concentrate, were used. As an estimate of the true values the reference values used in this evaluation were (a) the computed values, i.e., sum of the basal and spiked trace element concentration, and (b) the consensus values normally used in the Danish EQAS. This international evaluation of lead, cadmium, and chromium in human blood demonstrated that the use of lyophilized human blood concentrate quality control materials combined with this scheme is valuable in estimating the systematic error and the uncertainty of the analytical methods. For evaluating analytical performance, the computed values were preferable to the consensus values for lead and cadmium in human blood. Due to analytical difficulties suitable reference values were not established for chromium in blood. The study revealed analytical difficulties for cadmium and chromium in human blood. The assessment of laboratories according to established performance indexes indicates that few laboratories can maintain these performance indexes.

Internal and external quality control in the toxicological analysis of blood and urine samples in the Federal Republic of Germany

Due to a technical rule for dangerous agents (TRGS 410), issued by the Ministry of Labor in the Federal Republic of Germany in 1979, toxicological analyses in biological materials must be carried out under conditions of "statistical quality control". This quality-control scheme provides internal and external control programmes. For internal quality control, the results of many years of experience with five commercially available control specimens and one "home-made" control have been evaluated. The control samples showed good, comparable results over a long period. Except in a few cases, there was good agreement between our results and the assigned values. Since 1982, the German Society of Occupational Medicine has offered eight intercomparison programmes for external quality. In samples from 80-90 laboratories, 6 metals in blood and around 20 inorganic and organic parameters in urine in 2 concentration adjustments have been analysed. Successful participation was certified if both results obtained for one parameter were within the tolerance range (assigned value +/- 3 SD). The average success rate was around 60%.