Ultratrace extraction of persistent organic pollutants

We review and discuss ultratrace extraction as a high-volume technique for quantifying persistent organic pollutants in aqueous matrices, including its evolution, its acceptance by scientific and regulatory communities, influential factors, published validation efforts and analytical issues to bring to light existing assumptions concerning its effectiveness. We identify important methodological gaps, which may affect potential analytical outcomes, to orient future validation efforts or to pursue more effective alternatives. We also review the function and the purpose of quality-control features.Regarding analytical issues, we examine those related to sample definition (e.g., the distinction between high-volume sampling and extraction) and the major sources of bias associated with measurement technology – particularly sample-preparation and analysis steps in the laboratory.We discuss challenging old ways of viewing sampling and analysis as independent entities, emphasizing that a change in sample configuration (i.e. multi-component, multi-matrix and voluminous samples) must result in changes in the analytical protocol, if reliable data are desired. Current methods are not structured to facilitate the adaptation needed to ensure data are reliable, even if they are based on powerful isotope-dilution technology.We review the literature to identify deficiencies related to validation of the technique, to provide a basis for experiments that scientists can consider to test expressed concerns (confirm or refute) and to evaluate their effects on data quality (precision and accuracy). It is necessary to review the state of the science to ensure that we do not develop and validate a procedure whose design is at odds with its purpose.