I'm using the commercial GOx activity assay from Sigma Aldrich. I'm testing both commercial GOx just dissolved in PBS and GOx immobilized on my electrode nanomaterials. The absorbance at 570nm peaks at abs value over 1, and it declines over time. I thought the absorbance would increase as more H2O2 is produced then plateau to stay at a high absorbance level? When I took out the plate after the reading, and the hot pink color has turned fainter. Anyone have any insight on why/how this happens? Could something in the well have reacted with the dye and turned it back to the reduced form??