Quantitation of Arsenic in Biological Matrices: Use of Sector Field Inductively Coupled Plasma–Mass Spectrometry for Improved Accuracy and Specificity

Arsenic (As) and As-containing compounds have a wide array of applications in medicine, industry, and agriculture and has been associated with adverse health outcomes. In support of studies investigating the toxicity and toxicokinetic behavior of arsenic compounds, we developed and validated a high-resolution sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) method to quantitate total arsenic in Sprague-Dawley (SD) rat plasma and heart. Primary matrix standard curves prepared in male SD rat plasma were linear (<i>r</i> ≥ 0.999) over the range of 5 to 1250 ng As/mL plasma with accuracy determined as relative error (RE) was ≤ ±20% at the lower limit of quantitation (LLOQ) of 5 ng/mL and ≤ ±15% for all other concentrations. The method limit of detection (LOD) was 0.728 ng/mL plasma. Mean extraction recovery was 96.7%, with a relative standard deviation (RSD) of 4.0%. The method demonstrated acceptable inter- (≤ ±7.3% RE and ≤ 8.0% RSD) and intra-day (≤ ±14.9% RE and ≤ 6.8% RSD) accuracy and precision. Method selectivity was ≤ 20% of the response for the LLOQ. Method performance was also evaluated in SD rat heart by preparing QC samples in heart homogenate and quantifying using plasma calibration curve. The mean RE value was −3.8% and the RSD value was 3.4% demonstrating that the method is suitable for quantitation of arsenic in rat heart.