# Concentration average absorbance standard deviation 3

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ConcentrationAverage AbsorbanceStandard Deviation310.4420.2630.3740.43
3.Plot the data again and provide the graph, this time showing all of the raw data instead of averaging the replicates into one point. To do this you will need all of the data in single (x,y) data matrix. Please ask your instructor if you need help. Using this method, you will not have error bars. Does this change the R2value? How aboutthe linear equation? How does averaging change the results on the calibration?4.Fully describe and calculate the figures of merit for the calibration. Calculate the LoD, LoQ, and estimate the linear range.5.For each group, calculate the concentration of the unknown by the method of external standardsusing your graph from question 2 and report as average standard deviation.6.There’re about 7~11 groups in your class. For each group, calculate the concentration of the unknown by the method of standard addition and report as average standard deviation.7.Using statistical hypothesis testing (type 3: same sample, different method. Excel calls this t-test: Paired Two Samples for Mean) decide if the methods produce statistically similar or different results. Is external standardization different from the standard addition method? You have to put the data in excel following Table 3 below.Add as many rows as needed to include all class data. Remember, the data must bepaired, so if one point is discarded as an outlier you must discard both methods for that group. In other words, if a point loses its pair it can’t be included in the t-test.Group #Conc. of Unknown by ExternalStandardsConc. of Unknown byStandard Addition12348.Discuss the use of each of all threedifferent calibration methods (external standards, internal standards and standard addition). When is it appropriate to use them? Provide specific examples of situations where they would be most useful. 4
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