Determination of Elemental Composition in Soft Biological Tissue Using Laser Ablation Inductively Coupled Plasma Mass Spectrometry: Method Validation

Development of matrix-specific standards for LA-ICP-MS zinc analysis in sand flathead (Platycephalus bassensis)

The use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to analyse soft tissues is limited because of the lack of suitable certified reference materials resulting in difficulties with calibration. In this study, several laboratory-prepared thin agarose sections were tested as matrix-specific standards. Our results showed 1 mm thin agarose sections were suitable as calibration standards for LA-ICP-MS Zn analyses in fish muscle, especially when the signal intensity of 66Zn was normalised to 13C. The thin agarose standard sections were used for LA-ICP-MS Zn analyses in the muscle of melanised and non-melanised sand flathead collected from a polluted estuary and assigned with different melanisation scores. Zn levels in melanised regions of fish muscle were determined to be significantly higher than non-melanised regions across all melanisation scores, though Zn levels in the melanised regions of muscle were not significantly different between sand flathead with different melanisation scores. In non-melanised regions of muscle from fish with melanisation and fish unaffected by melanisation, Zn levels were around baseline levels. Overall, this study has successfully developed matrix-specific standards for LA-ICP-MS analysis of soft tissues, thus allowing broader application of this analytical technique in future environmental pollution studies.

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

Environmental monitoring programs that target fish tissues for selenium (Se) analysis present unique sampling and analytical challenges. Selenium monitoring programs ideally focus on egg/ovary sampling but frequently sample multiple tissues with varying lipid content, often target small-bodied fish species because of their small home ranges, and require reporting in units of dry weight. In addition, there is a growing impetus for nonlethal 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 Se concentrations accurately, precisely, and at desired detection limits. The objective of the present study was to stress-test some conventional analytical techniques used by commercial laboratories in terms of their ability to maintain data quality objectives (DQOs) in the face of sample weight constraints. Four laboratories analyzed blind a suite of identical samples, and data were compared against a priori DQOs 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. The present study has implications for accurately describing regulatory compliance in Se monitoring programs, highlighting some important considerations for achieving high data quality from low-weight samples. Environ Toxicol Chem 2023;42:2119-2129. © 2023 SETAC.