Junhyuk Jeon (Korea Racing Authority)

Junhyuk Jeon (Korea Racing Authority)

Junhyuk Jeon (Korea Racing Authority)

Jihee Han (Korea Racing Authority)

Namjib Ko (Korea Racing Authority)

Cobalt is an essential trace element and a hypoxia-mimetic agent that stimulates erythropoietin (EPO) production and is therefore regulated as a doping substance in racehorses. The regulatory thresholds for horses are set at 25 ng/mL as total cobalt in plasma. To address the limited robustness of the conventional method based on acid-based protein denaturation and precipitation, a rapid and robust ICP-MS method was developed and its measurement uncertainty was also evaluated. An iCAP RQ ICP-MS system (Thermo Scientific, USA) was employed. Equine plasma samples were simply diluted 50-fold with 0.5%(v/v) nitric acid and analyzed using germanium as an internal standard. Matrix-matched calibration was applied, providing excellent linearity with an r² value of 0.9996, and the limit of quantification was 2 ng/mL. Intraday precision ranged from 1.06% to 5.26%, while interday precision over three days ranged from 1.46% to 6.08% depending on concentration. Accuracy ranged from −0.72% to 6.62% relative to the nominal concentrations. Measurement uncertainty was evaluated from four contributing factors and was estimated as (25.7 ± 1.3) ng/mL (k = 2) at the regulatory threshold level. The method exhibited greater robustness than the conventional method, enabling a successful transition to routine analysis.​