This procedure is provided for reference only. The product manual may differ slightly. The product should be used as stated on the product manual included and delivered together with the product. Set standard, test samples and control wells. Aliquot 100μl of diluted standard into the standard wells. Aliquot 100μl of Standard Diluent buffer into control (zero) well. Aliquot 100μl of diluted samples into the sample wells. Incubate for 1 hr at 37 °C. Aliquot 100μl of Detection Reagent A to each well. Incubate for 1 hr at 37 °C. Wash 3 times. Aliquot 100μl of Detection Reagent B to each well. Incubate for 90 mins at 37 °C. Wash 5 times. Aliquot 90μl of TMB Substrate to each well. Incubate for 10-20 mins at 37 °C. Aliquot 50μl of Stop Solution. Measure the OD at 450 nm.