Protein-Free Sample Diluent is a protein-free matrix used for the dilution of biological samples (e.g. serum, cell culture media) into the useful range of antibody-sandwich or antigen-down ELISA format assays. This unique buffer contains a heterogeneous mixture of proprietary molecules that help reduce background noise associated with non-specific bridging of signal-generating conjugates to the plate well surface.
- Prepare standards in Protein-Free Sample Diluent.
- Dilute samples in Protein-Free Sample Diluent. Serum samples should generally be diluted at least 1:50 in order to minimize backgrounds caused by non-specific antibody binding. To dilute the sample 1:100, add 1 part sample to 99 parts Protein-Free Sample Diluent. For example, add 10 μL sample to 990 μL Protein-Free Sample Diluent for a total of 1,000 μL. Highly concentrated samples may need to be diluted 1:1,000 or more.
- Once diluted, run the assay according to the specific ELISA protocol.
- Analyze the data. If the samples were diluted 1:100, the dilution factor must be considered when calculating the value. For example, if the sample generated an OD value that correlates to 500 pg/ mL based on the standard curve, multiply by the dilution factor of 100 to yield a true concentration of 50,000 pg/mL = 50 ng/mL in the sample.