Question

A calibration curve was prepared to determine the concentration of albumin (MW 66500 g/mol) in a human serum sample. The serum sample was prepared by mixing it with a prepared bromocrestol green indicator buffer. Bromocrestol green creates a complex with albumin, which results in a colour change at 615 nm. Calibration standards were prepared by dissolving 133, 200, 266, 333 and 400 mg of albumin in 10.00 mL of the bromocrestol green buffer solution. The absorbances of the standards were 0.195, 0.285, 0.379, 0.467 and 0.562. A blank resulted in an absorbance of 0.012. Determine the molar concentration of albumin in the human serum sample if it gave an absorbance of 0.429. 463

Answer 1

molar concentration of albumin = 4.57 x 10^-4M

Explanation

The calibration curve gives the equation of best fit line as : y = 913.24x - 0.0002

Given : absorbance of sample = 0.429

blank corrected absorbance = (absorbance of sample) - (absorbance of blank)

blank corrected absorbance = (0.429) - (0.012)

blank corrected absorbance = 0.417

From the equation of line, x = (y + 0.0002) / 913.24

x = (0.417 + 0.0002) / 913.24

x = 0.000457 M