Method validation of multi-element panel in whole blood by inductively coupled plasma mass spectrometry (ICP-MS)

BACKGROUND: Analytical methods to measure trace and toxic elements are essential to evaluate exposure and nutritional status. A ten-element panel was developed and validated for clinical testing in whole blood. Retrospective data analysis was conducted on patient samples performed at ARUP Laboratories. METHODS: A method was developed and validated to quantify ten elements in whole blood by ICP-MS. Fifty microliters of sample were extracted with 950 μL of diluent containing 1 % ammonium hydroxide, 0.1 % Triton X-100, 1.75 % EDTA along with spiked internal standards. Four calibrators were used for each element and prepared in goat blood to match the patient specimen matrix. Samples were analyzed with an Agilent 7700 ICP-MS with a Cetac MVX 7100 μL Workstation autosampler. RESULTS: The assay was linear for all elements with inter- and intra-assay imprecision less than or equal to 11% CV at the low end of the analytical measurement range (AMR) and less than or equal to 4% CV at the upper end of the AMR for all elements. Accuracy was checked with a minimum of 40 repeat patient samples, proficiency testing samples, and matrix-matched spikes. The linear slopes for the ten elements ranged from 0.94 to 1.03 with intercepts below the AMR and R(2) ranging from 0.97 to 1.00. CONCLUSIONS: The multi-element panel was developed to analyze ten elements in whole blood to unify the sample preparation and increase batch run efficiency. The improved analytical method utilized matrix-matched calibrators for accurate quantification to meet regulatory requirements. The assay was validated according to guidelines for CLIA-certified clinical laboratories and was suitable for clinical testing to assess nutritional status and toxic exposure.