Help & FAQs: ELISA Kits

  • What is the difference between limit of detection (LOD) and lower limit of quantification (LLOQ)?
  • The lower limit of detection (LOD) is also known as the minimum detectable dose (MDD). This is calculated by adding two standard deviations to the mean optical density value of twenty zero standard replicates and calculating the corresponding concentration. The value obtained from this calculation is considered the absolute minimum value that could be distinguished from the background.The lower limit of quantification (LLOQ) is the lowest point on standard curve. This value will give the lowest quantifiable concentration value in samples. Any sample values that fall below that of the lowest standard should be reported as less than the LLOQ.
  • Why do some DuoSets have different Standard Curve ranges than the Quantikine ELISA of the same analyte?
  • Our Quantikine kits are developed to test multiple sample types. We develop kits that generally allow serum and plasma samples to be read on the standard curve with minimal dilution, while obtaining a robust standard standard curve and low NSB valuesDuoSet ELISAs are validated for Cell Culture Supernates only which may require a differnt detection range than do other, more complex sample types.
  • Why is my wash buffer yellow?
  • R&D Systems wash buffers contain ProClin® 300. ProClin 300 is a preservative used in diagnostic and research reagents that is clear to pale yellow in color. The yellow color may become more pronounced over time and occurs more rapidly at room temperature than at 2-8 °C. This color change has no effect on efficacy of the preservative or the performance of the assay.