Calculation of Biotinidase Enzyme Activity from absorbance measurements made at 550nm. The substrate blank (well B1 in the default layout) is corrected by the reagent blank (well A1 in the default layout). The standards and the blanks are corrected by the reagent blank. The unknowns are corrected by their own blank which has also been corrected by the corrected substrate blank. The activity of each unknown is measured from the standard curve using linear regression.