Rapid analysis for plutonium-239 in 1 ml of urine by magnetic sectorinductively coupled plasma mass spectrometry with a desolvating introduction system

Abstract

The Centers for Disease Control and Prevention has a mission to protect and promote public health, which includes investigation of environmental exposures to toxic substances that could threaten health. Plutonium is an environmentally available substance that is chemically and radiologically toxic and represents a potential health threat from excessive exposure. Inductively coupled plasma mass spectrometry (ICP-MS) is a sensitive method for assessing environmental or unintentional exposure to these and other actinides. We report here a magnetic sector instrument method in which a desolvating introduction system is used to provide rapid, sensitive emergency response analysis for ²³⁹Pu in only 1 mL of urine without digestion or coprecipitation. ²³⁹Pu was separated from U and interfering urine organic substances by solid phase extraction. The within run limit of detection (LOD) was 0.16 fg mL⁻¹ for 1 mL of urine even though originally spiked to 1018 ng L⁻¹ of depleted U. A more rigorous LOD of 1.4 fg mL⁻¹²³⁹Pu was based on 3 “total” standard deviations in the presence of the same U concentration. At below 10⁶ atoms of ²³⁹Pu detectable in 1 mL of urine, this method is sufficiently sensitive for elevated emergency exposure assessment with high throughput. The precision for 10 duplicate samples was within 3.7% relative “total” standard deviation (RSD, within and between run) for a 9.96 fg mL⁻¹²³⁹Pu-spiked urine sample and within 2.2% for a 99.6 fg mL⁻¹²³⁹Pu-spiked urine sample. The method was demonstrated to be accurate within 2.6% of the Los Alamos National Laboratories target value at 99.6 fg mL⁻¹, to within 1.0% of target value at 9.96 fg mL⁻¹ and within 1.2% at 0.996 fg mL⁻¹, just below the method LOD.