Stop Solution is 0.16M sulfuric acid for use with the ELISA substrate 3,3’,5,5’ - tetramethylbenzidine (TMB). In the presence of horseradish peroxidase (HRP) enzyme conjugates, TMB and peroxide react to produce a blue byproduct having maximum absorbance at 605nm. The color intensity is proportional to the amount of HRP activity, which in turn is related to the levels of target analyte in an optimized ELISA procedure. Addition of sulfuric acid stop solution changes the color to yellow (absorbance maximum at 450nm), stabilizing the color development to enable accurate measurement of the intensity at 450nm using a spectrophotometer or plate reader.

Features of Stop Solution:

• Size: 55 mL (sufficient for about five 96-well microplates)
• Storage: Shipped at ambient temperature. Store at room temperature or 2-8°C.
• Application: ELISA: Following TMB incubation, add an amount of stop solution equal to the amount of TMB substrate added to each well of the ELISA plate (typically 50–100 µL per well). Use at full strength.