Analysis of Selenium in Fish Tissue: An Interlaboratory Study on Weight Constraints.

Abstract

Environmental monitoring programs that target fish tissues for selenium (Se) analysis present unique sampling and analytical challenges. Se monitoring programs ideally focus on egg/ovary sampling but frequently sample multiple tissues with varying lipid content, often target small-bodied fish species due to their small home ranges, and require reporting in units of dry weight. Additionally, there is a growing impetus for non-lethal tissue sampling in fish monitoring. As a result, Se monitoring programs often generate low-weight tissue samples of varying lipid content, which challenges analytical laboratories to quantify tissue selenium concentrations accurately, precisely, and at desired detection limits. The objective of this study was to stress-test some conventional analytical techniques used by commercial laboratories in terms of their ability to maintain data quality objectives in the face of sample weight constraints. Four laboratories analyzed blind a suite of identical samples, and data were compared against a priori data quality objectives for accuracy, precision, and sensitivity. Data quality tended to decrease with decreasing sample weight, particularly when samples were less than the minimum weights requested by the participating laboratories; however, effects of sample weight on data quality were not consistent among laboratories or tissue types. This study has implications for accurately describing regulatory compliance in selenium monitoring programs, highlighting some important considerations for achieving high data quality from low-weight samples.