# User:Moira M. Esson/Notebook/CHEM-571/2013/09/04

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## Objectives

• Perform error analysis on the compiled data calibration curve.
• Determine the standard deviation for the data points.
• Determine the confidence interval for 90% and 95% confidence.
• Determine if any data can be ruled out using a Q-test.
• Determine the molar extinction coefficient for both adenosine and inosine.
• Determine the concentration of an unknown adenosine sample(taken from Javier's group).
• Perform Grubb's test on outlying peak of adenosine molar extinction coefficent graph.
• Perform data analysis on molar extinction coefficient graphs(both adenosine and inosine).

## Group calibration curve data

Figure 1. CHEM-571 Calibration Curve for Adenosine

• The Grubb's test will be employed to determine whether the points that lie outside of the line of best fit are outliers

Figure 2. CHEM-571 Calibration Curve for Inosine

Table 1. Molar absorptivity for Adenosine at a wavelength of 259nm and Inosine at a wavelength of 249nm

 Molar Absorptivity(Lmol-1cm-1) ' Adenosine 14025 Inosine 11007

Matt Hartings What wavelength does this molar absorptivity correspond to?

Table 2. Standard deviation of Inosine Absorbance values

 Comcentration(M) Standard Deviation 4.80E-05 0.10707708 4.00E-05 0.12254917 3.20E-05 0.0943149 2.40E-05 0.06671357 1.60E-05 0.04841797 8.00E-06 0.04748368

Table 3. Standard deviation of Adenosine Absorbance values

 Concentration(M) Standard Deviation 3.00E-05 0.072537576 2.50E-05 0.045680412 2.00E-05 0.064123319 1.50E-05 0.056753854 1.00E-05 0.0313289 5.00E-06 0.046559639

Table 4. 95% Confidence Intervals for Adenosine Absorbance values

 Concentration(M) Confidence Interval 3.00E-05 0.063580821 2.50E-05 0.04003991 2.00E-05 0.056205534 1.50E-05 0.049746033 1.00E-05 0.027460487 5.00E-06 0.040810573

Table 5. 90% Confidence Intervals for Adenosine Absorbance Values

 Concentration(M) Confidence Interval 3.00E-05 0.053358707 2.50E-05 0.033602552 2.00E-05 0.047169171 1.50E-05 0.041748187 1.00E-05 0.023045567 5.00E-06 0.034249313

Table 6. 95% Confidence Intervals for Inosine Absorbance Values

 Concentration(M) Confidence Interval 4.80E-05 0.093855474 4.00E-05 0.10741711 3.20E-05 0.082669136 2.40E-05 0.058475948 1.60E-05 0.042439442 8.00E-06 0.041620516

Table 7. 90% Confidence Intervals for Inosine Absorbance Values

 Concentration(M) Confidence Interval 4.80E-05 0.078765997 4.00E-05 0.09014728 3.20E-05 0.069378126 2.40E-05 0.049074562 1.60E-05 0.035616303 8.00E-06 0.034929038

Table 8. Q-test at 90% confidence for Inosine Absorbance Values

 Comcentration(M) Qexp values Suspected outlier(Abs) 4.80E-05 0.435606061 0.331 4.00E-05 0.605769231 0.189 3.20E-05 0.880658436 0.171 2.40E-05 0.987804878 0.128 1.60E-05 0.475806452 0.089 8.00E-06 0.534883721 0.004

• Note: With 5 data points Qc=0.64. As such, data points 0.171 and 0.128 can be discarded with 90% confidence

Table 9. Q-test at 90% confidence for Adenosine Absorbance Values

 Concentration(M) Suspected Outliers(Abs) Qexp 3.00E-05 0.558 0.794444444 2.50E-05 0.442 0.705357143 2.00E-05 0.406 0.8625 1.50E-05 0.304 0.675496689 1.00E-05 0.195 0.5 5.00E-06 0.136 0.405405405

• Note: With 5 data points Qc=0.64. As such, data points 0.558, 0.442, 0.406, and 0.304 can be discarded with 90% certainty.

Table 10. Grubb's Test for Adenosine Absorbance Values

 Concentration(M) Suspected Outliers(Abs) Gexp 3.00E-05 0.558 1.753573888 2.50E-05 0.442 1.725028241 2.00E-05 0.406 1.75599146 1.50E-05 0.304 1.481520326 1.00E-05 0.195 1.532131655 5.00E-06 0.136 1.426127891

• Note: With 5 data points at a 95% confidence level Gc=1.67. As such, absorbance values 0.558, 0.442 and 0.406 can be discarded with 95% confidence.

Figure 3. Absorption Spectrum of Unknown Concentration

• Using the molar extinction coefficient determined from the calibration curve above the concentration of the unknown is 4.7344E-5 M.
• Based on the calibration curve, the average error in this calculation is 1%, shown in Table 11(shown below).

Table 11. Calculations relating to the uncertainty in the unknown concentration

 Absorbance Concentration (M) Std. dev. Error(%) Average Std.dev Average Error(%) 0.4308 3.07166E-05 0.185562176 2.350608861 0.078942175 1 0.3632 2.58966E-05 0.131895429 1.670785353 0.2934 2.09198E-05 0.086071285 1.090308 0.209 1.4902E-05 0.043674771 0.553250165 0.147 1.04813E-05 0.021605919 0.273692974 0.0696 4.96257E-06 0.004843469 0.061354647

Matt Hartings Based on your calibration curve, what is the error in this measurement?