Inductively coupled plasma mass spectrometry determination of hepatic copper, manganese, selenium, and zinc concentrations in relation to sample amount and storage duration

Trace mineral status is a critical component of bovine health. Impairment of physiological processes, caused by trace mineral toxicities or deficiencies, can be potential underlying factors of disease. Historically, the status of critical trace minerals, such as copper, manganese, selenium, and zinc, has been evaluated through the analysis of hepatic tissue. We assessed variation of these 4 elements between homogenized liver and samples of 0.02 g, 0.1 g, 0.5 g, and 1.0 g. We also evaluated concentration differences in copper, manganese, selenium, and zinc among samples stored under different durations. No differences in concentrations of copper, manganese, selenium, or zinc were observed among samples stored frozen for 3, 7, and 14 d post-collection. Statistical differences in concentrations of selenium and zinc were observed between 0.02-g biopsy samples and larger samples. Moisture content differed between 0.02-g biopsies and larger samples and over time. Results indicate that as little as 0.02 g of hepatic tissue dried to ~0.006 g is reliable for interpretation of trace mineral status and determination of toxicities and deficiencies in cattle pertaining to copper, manganese, selenium, and zinc, despite the small differences observed.