Interlaboratory exercise on steroid estrogens in aqueous samples

An inter-laboratory comparison exercise was organized among European laboratories, under the aegis
of EU COST Action 636: “Xenobiotics in Urban Water Cycle”. The objective was to evaluate the
performance of testing laboratories determining “endocrine disrupting compounds” (EDC) in various
aqueous matrices. As the main task three steroidal estrogens: 17α-ethinylestradiol, 17β-estradiol and
estrone were determined in four spiked aqueous matrices: tap water, river water and wastewater treatment
plant influent and effluent using GC-MS and LC-MS/MS. Results were then compared and discussed
according to the analytical techniques applied, the accuracy and reproducibility of the analytical methods
and the influence of the sample matrices. Out of a total of fourteen European laboratories that participated
in the exercise, eleven laboratories submitted results.
Statistical evaluation of results revealed that the number of outliers in this exercise was low taking into
account the complexity of sample matrices and the differences in analytical methods applied. Consensus
values are also in good agreement with the spiked concentrations for each compound, with the exception
of the wastewater influent sample for which the obtained values differed significantly. This was in
agreement with standard deviation of repeatability, inter-laboratory standard deviation and standard
deviation of reproducibility. Overall the results obtained in this inter-laboratory exercise reveal a high
level of competence among the participating laboratories for the detection of steroidal estrogens in water
samples indicating that GC-MS as well as LC-MS/MS can equally be employed for the analysis of natural
and synthetic hormones.