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

From OpenWetWare
Jump to: navigation, search
Owwnotebook icon.png Project name Report.pngMain project page
Resultset previous.pngPrevious entry      Next entryResultset next.png

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
Chem571groupadenosinecalibration09082013.png

  • 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
Chem571inosinecalibrationcurve09082013.png
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.

Unknown Adenosine Solution

Figure 3. Absorption Spectrum of Unknown Concentration
Unknownadenosine09042013zem.png

  • 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?