Full Validation of a High Resolution ICP-MS Bioanalysis Method for Iron in Human Plasma with K2EDTA

Purpose: To validate a bioanalytical inductively coupled plasma mass spectrometry (ICP-MS) method for quantification of iron in human plasma with K2EDTA (matrix). This method was validated using typical bioanalytical validation parameters. Materials and methods: Iron reference standards and germanium internal standard (IS) were from Ultra Scientific. Reagent water had a resistivity ?18 M?cm. Nitric acid and hydrochloric acid were ultra pure grade. Blank matrix was purchased from BioReclamation. Linearity was assessed using eight standards prepared in proxy matrix over a range equivalent to 0.5-20 ?g iron/mL of matrix at the beginning and end of each run. Quality control (QC) samples were prepared by fortifying matrix at 0.5, 1.5, 10, 15 and 100 ?g/mL. A blank containing IS and a double blank were included in every run. Selectivity was evaluated using six different lots of matrix fortified with IS and analyte at the LLOQ level. A Thermo-Finnigan ELEMENT2 High Resolution ICP-MS was used to analyze prepared samples. Results: System suitability, selectivity, carryover, and ruggedness all met the acceptance criteria. Linearity was consistently demonstrated. Recoveries for all calibration standards and QCs were within the acceptance criteria. Freeze/thaw was demonstrated for 4 cycles. Bench top reproducibility was successful following 53 hours of ambient storage. Reinjection reproducibility was successful following 96 hours of ambient storage. Extract stability was successful following 190 hours of ambient storage. IS solution stability was successful following 29 days of ambient storage. Calibration standard stability was successful following 8 days of ambient storage. Analyte stock solution stability was successful following 29 days of ambient storage. Long term storage stability was successful following 31 days at 2 to 8°C, 31 days at -15 to -25°C, and 30 days at ?70 to -90°C storage. Conclusion: This bioanalytical ICP-MS method was successfully validated for the quantification of iron in human plasma with K2EDTA.