Which method is NOT used for apolipoprotein assays?

• A. Immunonephelometric
• B. Immunoturbidimetric
• C. ELISA
• D. Gel electrophoresis

Answer: (D)

Measuring apolipoproteins relies on antibody-based detection to quantify a specific protein in a sample. Immunonephelometric and immunoturbidimetric methods detect antigen–antibody complexes in solution by measuring light scatter or transmission, giving direct quantitative results for the apolipoprotein. ELISA uses antibodies on a plate to capture and then quantify the target protein, also providing precise measurements with standard curves. Gel electrophoresis, by contrast, separates proteins based on size and charge, revealing bands that indicate which proteins are present but not providing direct, routine quantification of specific apolipoproteins. It can show patterns or be used in conjunction with further detection (like Western blot), but it’s not a standard quantitative assay for apolipoproteins in the clinical setting.