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correct answer is [glucose]= 99.2mg/100mL , just need help getting the answer! 1

ID: 589871 • Letter: C

Question

correct answer is [glucose]= 99.2mg/100mL , just need help getting the answer!

16-10. Glucose in blood serum can be determined spectrophotometrically by formation of a col 50.0-L serum samples were treated with var- the following ored complex with o-tolidine. Six identical ious concentrations of glucose and taken through the procedure, producing results: Amount glucose added (14) Absorbance 10 25 40 60 75 0.230 0.272 0.340 0.416 0.507 0.568 Prepare a standard addition calibration plot and calculate the glucose concentration in the serum in units of mg/100 mL

Explanation / Answer

This is method of standard addition

let Cx be concentration of glucose in solution without standard

Cs be concentration of glucose standard added

Ax be absorbance of glucose in solution without standard

As be absorbance of glucose with standard

So,

Cx/(Cx + Cs) = Ax/(Ax + As)

Taking data from the table,

Cx/(Cx + 10) = 0.230/0.272

0.272Cx - 0.230Cx = 2.30

Cx = 2.30/0.042 = 54.762 ug in 50uL

     = 54.762 ug x 0.001/50 x 0.001

     = 54.762 mg/50 ml

     = 109.524 mg/100 ml

Similarly from other values from table

when glucose standard added = 25 ug

glucose concentration = 104.545 mg/100 ml

when glucose standard added = 40 ug

glucose concentration = 98.925 mg/100 ml

when glucose standard added = 60 ug

glucose concentration = 99.639 mg/100 ml

when glucose standard added = 75 ug

glucose concentration = 102.071 mg/100 ml

average [glucose] in serum sample = 102.941 mg/100 ml