6. Standard addition was performed to determine the iron contained in Shiraz red wine from south central Australia using a flame-atomic absorption spectrometer. Absorbance (A.U.) Fe content in South Australian red wine 0.12 0.1 0.08 0.06 0.04 0.02 0 0 0.5 y = 0.0506x +0.013 R² = 0.9987 1 1.5 Concentration (ppm) 2 A) Calculate the concentration of iron in the red wine sample (in ppm). 2.5 B) How is the R2 value used in linear regression? What is an ideal R2 value? What does R² value tell you? C) Should the linear regression line in the above plot go through 0,0? Yes/No D) Why does the line not go through 0,0 on the standard addition plot? 3 E) The absorbance measurement was obtained three times for each sample and averaged by the instrument. Is the %RDS more likely to be higher when the actual concentration of the sample or standard being analyzed is low or high? Why?

6. Standard addition was performed to determine the iron contained in Shiraz red wine from south central Australia using a flame-atomic absorption spectrometer. Absorbance (A.U.) Fe content in South Australian red wine 0.12 0.1 0.08 0.06 0.04 0.02 0 0 0.5 y = 0.0506x +0.013 R² = 0.9987 1 1.5 Concentration (ppm) 2 A) Calculate the concentration of iron in the red wine sample (in ppm). 2.5 B) How is the R2 value used in linear regression? What is an ideal R2 value? What does R² value tell you? C) Should the linear regression line in the above plot go through 0,0? Yes/No D) Why does the line not go through 0,0 on the standard addition plot? 3 E) The absorbance measurement was obtained three times for each sample and averaged by the instrument. Is the %RDS more likely to be higher when the actual concentration of the sample or standard being analyzed is low or high? Why?

Principles of Modern Chemistry

8th Edition

ISBN:9781305079113

Author:David W. Oxtoby, H. Pat Gillis, Laurie J. Butler

Publisher:David W. Oxtoby, H. Pat Gillis, Laurie J. Butler

Chapter20: Molecular Spectroscopy And Photochemistry

Section: Chapter Questions

Problem 6P

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