Question

Using Excel and least-square line (aka linear regression) fitting, find the slope, y-intercept, and correlation coefficient (R²) for the calibration of Absorbance (A) vs. Concentration (C in M) of Vitamin C at 246 nm UV light as outlined for Beer’s Law: {C, A} = {{1.414, 81.10}, {1.359, 84.38}, {0.637, 28.30}, {1.829, 86.46}, {1.520, 94.40}, {0.260, 29.33}, {1.186, 44.50}, {1.509, 70.76}}. Formally plot the points with the superimposed fitted line with the proper title, axis labels and units, etc. What is the unknown molar concentration of Vitamin C if the absorbance is measured to be 6.551? Did you interpolate or extrapolate to arrive at your final concentration?

Answer 1

Part-A: Solution

Part-B) At the absorbance value of 6.551, we can use a linear equation y = 0.017x + 0.1089 to find the concentration of vitamin C i.e. = 0.2204

And Yes, linear regression can be interpolated or extrapolated to arrive at your final concentration