Determination of organochlorine compounds, petroleum hydrocarbons, and sterols in a sediment sample, IAEA-383. Results of an intercomparison exercise

A worldwide interlaboratory analytical comparison exercise was organised using a lagoon sediment as sample material (IAEA-383). A total of 54 laboratories from 41 countries reported results for organochlorine pesticides, PCB congeners, aliphatic and aromatic petroleum hydrocarbons, and sterols. The statistical treatment of the data indicates that the accurate determination of these organic contaminants in sediments is still a delicate task for environmental laboratories and, for many compounds, the relative standard deviations of the mean concentration values are relatively large. The difficulties with analytical accuracy and precision are nearly the same in several regional programmes and they do not seem geographically biased. Thus, further progress is needed and may be achieved with analytical training and reinforced participation of the laboratories in proficiency testing schemes. Nevertheless, the statistical treatment of the data reported by the laboratories participating in this exercise allowed the assignment of reference values for many analytes. Based on the experience of previous exercises, the assigned reference values are likely a very good estimate of the true concentrations of analytes, although the confidence limits of those Values are relatively broad. This sediment sample can now be used as a Reference Material in Quality Control and assist laboratories with assigning concentration values in environmental samples of similar matrix. In particular for sterols this is the first sediment material available with information on analyte concentrations.