binding capacity that human serum albumin HSA 67000 Da a transfer protein found in human blood has for a novel molecular probe EO550 MW 691 85 g mol When bound to HSA EO550 absorbs light strongly at 550 nm When unbound both HSA and EO550 have negligible absorbance at 550 nm added L 3 70 8 60 9 50 10 40 11 20 12 40 13 30 15 40 corrected absorbance 10 40 L ea absorbance 0 111 0 210 0 232 0 251 0 254 0 257 0 256 0 255 The researcher prepared eight individual samples each containing 0 74 mg HSA dissolved in 150 L of a pH 7 4 phosphate buffered saline solution To each of the eight samples a different volume of 1900 0 M EO550 was added and the absorbance was measured at 550 nm The observed absorbance measured at 550 nm for each added volume of the EO550 solution is shown in the table As more EO550 is added to the HSA solution the absorbance increases as more EO550 binds to available sites on the HSA protein When the binding sites are fully occupied the absorbance will no longer increase level off as more EO550 is added What is the corrected absorbance when 10 40 L of the EO550 solution is added to the 150 0 L HSA solution Construct a graph of the corrected absorbance y axis versus the volume of titrant added x axis What is the estimated endpoint of the titration Calculate the mass of EO550 added to reach the endpoint