A sandwich ELISA is an immunoassay format that uses two antibodies to detect a target protein: one capture antibody and one detection antibody. This format is widely used for biomarker measurement because it can offer strong specificity and sensitivity when the antibody pair is well matched. 

Learn More: 4 types of ELISAs: Direct, Indirect, Sandwich, Competitive

A matched antibody pair consists of two antibodies that recognize different compatible epitopes on the same target protein. Matched pairs are commonly used in sandwich ELISA development and must be selected carefully to support reliable target capture and detection.

Spike recovery measures how well an assay can detect a known amount of added target analyte in a real sample matrix, such as serum, plasma, or cerebrospinal fluid (CSF). Poor spike recovery can indicate matrix interference, poor assay compatibility, or other sample-dependent effects. 

Dilution linearity evaluates whether measured analyte concentration changes proportionally when a sample is serially diluted. It helps determine whether the assay behaves consistently across sample concentrations and whether matrix effects may be affecting quantification.

Parallelism assesses whether a diluted biological sample produces a response curve that runs parallel to the standard curve. Good parallelism suggests that the assay is measuring the endogenous analyte in the sample similarly to the reference standard.

LOD stands for limit of detection, which is the lowest amount of analyte an assay can reliably detect. LOQ stands for limit of quantification, which is the lowest amount of analyte that can be measured with acceptable accuracy and precision.

Matrix effect refers to interference caused by components in a biological sample, such as serum proteins, lipids, anticoagulants, or other molecules. These effects can alter antibody binding, signal generation, or quantification accuracy in ELISA and other immunoassays.

Assay validation is the process of evaluating whether an assay performs reliably for its intended use. Validation may include assessment of sensitivity, specificity, precision, accuracy, linearity, recovery, reproducibility, and performance in relevant sample matrices.

Learn more: 7 Parameters for Selecting an Antibody to Power Your ELISA