ELISA Kits

Choosing the Right ELISA Format

Proteintech offers four ELISA product formats. The right choice depends on your target analyte, required sensitivity, time constraints, and whether you need a ready-to-use kit or a customizable assay.

Sample Type Considerations

Serum and plasma are the most common sample types for ELISA. When collecting blood samples, the choice of anticoagulant matters — EDTA, heparin, and citrate plasma can give different readings for some analytes. Check the product datasheet for tested and recommended sample types. Hemolyzed samples should be avoided as released hemoglobin can interfere with colorimetric detection.

Cell culture supernatants can be measured directly in most cases. For adherent cell cultures, collect media at defined time points and centrifuge briefly to remove cell debris. Serum-free media is preferred when possible, as serum proteins can contribute to background signal.

Tissue lysates require careful preparation. Total protein concentration should be normalized across samples, and lysis buffers containing high detergent concentrations can interfere with antibody binding. Dilute lysates and run a pilot experiment at multiple dilutions to find the optimal range.

Getting Accurate Results

• Run standards in duplicate or triplicate on every plate — do not reuse a standard curve from a previous experiment
• Include a blank well (substrate only) and a negative control (sample matrix without analyte) to calculate true background
• Avoid freeze-thaw cycles — aliquot samples and standards on first use. Most cytokines degrade measurably after 2–3 freeze-thaw cycles
• Use Proteintech's ELISA Calculator (available free on the site) for dilution planning and standard curve fitting
• Equilibrate reagents to room temperature before use — cold reagents slow enzyme kinetics and reduce signal