Inductively coupled plasma-mass spectrometry (ICP-MS) is a useful method for assessing environmental or occupational exposure to thorium, uranium, plutonium, and other actinides. In this study, we investigated method parameters for practical balance between sample preparation time, volume, and sufficient sensitivity (limit of detection 47 fg per 10 mL urine) for reasonable exposure assessment of the maximum number of samples in the minimum possible turnaround time for unintentional exposures or emergency response situations using magnetic sector desolvation-ICP-MS. The method accuracy for urinary 239Pu determination was within 2% of target at 100 pg L−1
(p > 0.9995) and 7.7 pg L−1
(p > 0.9995), whereas our data was 16% disparate to target at approximately 45 pg L−1
(p < 0.0005) and 41% at approximately 37 pg L−1
(p > 0.0005) concentrations for data obtained from the determination of 239Pu in internally prepared urine pools and in pools characterized by an external agency. Precisions based on relative standard deviations ranged from 8% at 100 pg L−1 to 39% at 7.6 pg L−1239Pu.