Dried blood spot sampling of landlocked Arctic char (Salvelinus alpinus) for estimating mercury exposure and stable carbon isotope fingerprinting of essential amino acids

• Published in: Environmental Toxicology and Chemistry
• Main Authors: Barst, Benjamin D., Wooller, Matthew J., O’Brien, Diane M., Santa-Rios, Andrea, Basu, Niladri, Köck, Günter, Johnson, Jessica J., Muir, Derek C.G.
• Format: Text
• Language: English
• Published: 2020
• Subjects: Article; Arctic; Salvelinus alpinus
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7748106/; http://www.ncbi.nlm.nih.gov/pubmed/32045959; https://doi.org/10.1002/etc.4686

Dried blood spots (DBS), created by applying and drying a whole blood sample onto filter paper, provide a simple and minimally invasive procedure for collecting, transporting, and storing blood. Because DBS are ideal for use in field and resource-limited settings, we aimed to develop a simple and accurate DBS-based approach for assessing mercury (Hg) exposure and dietary carbon sources for landlocked Arctic char, a sentinel fish species in the Arctic. We collected liquid whole blood (from the caudal vein), muscle, liver, and brains of Arctic char (n=36) from eight lakes spanning a Hg gradient in the Canadian High Arctic. We measured total Hg concentrations ([THg]) of field-prepared DBS and Arctic char tissues. Across a considerable range, [THg] of DBS (0.04 μg/g to 3.38 μg/g ww) were highly correlated with [THg] of all tissues (r(2) range = 0.928 to 0.996). We also analyzed the compound specific carbon isotope ratios (expressed as δ(13)C values) of essential amino acids (CSIA-EAAs) isolated from DBS, liquid whole blood, and muscle. The δ(13)C values of five EAAs (δ(13)C(EAAs); isoleucine, leucine, phenylalanine, valine, threonine) from DBS were highly correlated with δ(13)C(EAAs) of liquid whole blood (r(2) range = 0.693 to 0.895) and muscle (r(2) range = 0.642 to 0.881). The patterns of δ(13)C(EAAs) of landlocked Arctic char were remarkably consistent across sample types and indicate EAAs are most likely of algal origin. Because a small volume of blood (~50 μL) dried on filter paper can be used to determine Hg exposure levels of various tissues and to fingerprint carbon sources, DBS sampling may decrease the burdens of research and may be developed as a non-lethal sampling technique.