Question

2. The AMR for a method for measuring glucose has been determined by the manufacturer to be 20-500 mg/dL A. The data for its verification study is shown below. Is the method's linearity verified for this range? Standard Standard [Glucose] mg/dL Absorbance Blank Standard 1 Standard 2 Standard 3 Standard 4 Standard 5 Standard 6500 0.000 0.050 0.099 0.201 0.298 0.402 0.501 50 100 200 300 400 B. The method allows a maximum dilution by a factor of 10. What is the Clinical Reportable Range? C. What is the glucose concentration in an unknown if the absorbance reading is 0.075? D. What should be done if the absorbance reading of the unknown sample for glucose is 0.602? E. How should the result be reported if the absorbance reading of the diluted unknown sample for glucose is 0.602?

Answer 1

A. Yes, as the absorbance is directly proportional to the standard glucose concentrations given in the table. Thus linearity is verified for the given range.

B. Clinical Reportable Range is 2-5000 mg/dL.

C. The concentration of unknown sample ( absorbance reading 0.075) 75 mg/dL.

Calculation: ( 0.075x 50)/0.05= 75 mg/dL.

D. If the absorbance is 0.602, the concentration will be 600 mg/dL. But as the concentration is not under AMR check therefore report cannot be given. Only if the sample is half diluted and then run, the concentration that given in linearity. Therefore report can be given by multiplying 2 with the concentration of the diluted sample.

E. If the absorbance of diluted unknown sample is 0.602 which represents 600 mg/dL glucose concentration that is beyond linearity therefore further dilutions can be needed for generation of report.