Establishment and Application of a Dual Immunoassay Method Based on ICP-MS for Stable Element Labeling Antibodies

Background: To establish a dual immunoassay based on inductively coupled plasma mass spectrometry (ICP-MS) with stable element labeling antibodies for the simultaneous detection of alpha-fetoprotein (AFP) and prostate-specific antigen (PSA) in serum and evaluate its performance and clinical sample validation.

Methods: The immunoassay system based on the double antibody sandwich method was established using magnetic beads as solid-phase carriers and rare earth elements europium (Eu) and samarium (Sm) as element tags. The test conditions were optimized. According to the Clinical Laboratory Standards Institute (CLSI) guidelines and the "Guidelines for Performance Validation of Clinical Chemistry Quantitative Testing Procedures," performance validation was conducted using the established method, followed by clinical sample validation.

Results: The LOD and AMR for AFP were 0.76 ng/mL and 1.5-1200 ng/mL, respectively; the LOD and AMR for PSA were 0.41 ng/ mL and 0.5-250 ng/ mL, respectively. The intra-batch precision for AFP and PSA was all less than 3.33%, and the inter-batch precision for AFP and PSA was all less than 4.97%. The recoveries of AFP and PSA were 95.08%-104.18% and 97.65%-100.72%, respectively. The correlation coefficients between the established and the CLIA methods were r = 0.9930 for AFP and r = 0.9852 for PSA.

Conclusions: We have developed a dual immunoassay method based on ICP-MS, which can quantitatively detect AFP and PSA in serum within a single analysis. This method exhibits good precision, a wide linear range, and high specificity, meeting the requirements for clinical sample detection and holding potential for clinical application.