Reference no: EM132439081

Problem: The fluorescence of a series of acidic solutions of quinine was each determined five times; the results are given below:

Concentration (ng·mL-1 ) 0 10 20 30 40 50

Fluorescence intensity (Counts·s -1 ) 4 22 44 60 75 104

3 20 46 63 81 109

4 21 45 60 79 107

5 22 44 63 78 101

4 21 44 63 77 105

Required:

Question 1: Calculate the confidence limits for the concentration of a solution with a fluorescence intensity of 90 counts·s-1 .

Question 2: A solution of unknown quinine concentration gave a fluorescence signal of 155 counts·s-1. A 5 mL aliquot of solution was pipetted into a 10 mL volumetric flask, which as then filled with the appropriate solvent to the mark. The fluorescence intensity of the diluted solution was measured to be 52 counts·s-1. What is the concentration of quinine in the original sample?

Question 3: Still related to (b). Is the relationship between fluorescence intensity and quinine concentration linear at the concentration of the unknown? Justify your answer.