Chemistry 155 Introduction to Instrumental Analytical Chemistry

More documents

Recommendations

Info

Chem 155 Unit 1 Page 54 of 3131.15.1 Internal Standards Example:In HPLC the sample is injected into a flowing stream, and the signalis a peak in a plot of absorbance versus time (a chromatogram).Often the volume of the injection will vary from injection to injection,so the peaks will vary in size!Peak 1 is theinternal standard.100 ppm NaNO 3 ,480 All mAu . sabsorbance10.5Peaks 2, 3 and 4 are otheringredients in the sample.1Peak 5 is theanalyte, a caffeinestandard, 25 ppm,530 mAu . sabsorbance100 ppm NaNO 3 ,520 mAu . sabsorbance00 400 800 1200 1600 2000 2400 2800 3200 3600 4000time / s10.500 400 800 1200 1600 2000 2400 2800 3200 3600 4000time / s10.523Chromatogram1 is a standard.Did the caffeineconcentrationincrease fromchromatogram1 to 2?Did the caffeineconcentrationincrease inchromatogram1 to 3?Unknowncaffeine conc.630 mAu . s00 400 800 1200 1600 2000 2400 2800 3200 3600 4000time / sPage 54 of 313
Chem 155 Unit 1 Page 55 of 3131.15.2 Internal Standards CalculationHow about calculating the actual concentration of the sample in 3above?StandardS'A − STDCA − STDS'IS − STDCIS− STD530 mAu . s25 ppm480 mAu . s100 ppmSCA−STDIS−STDk ==S'IS−STDCA−STDS'ANmm' 530⋅100ANIS480⋅25= 4.417 unitless630 mAu . sSampleS'ISCISCANS'S'ISCk520 mAu . s100 ppmAN IS=630⋅100520⋅4.417= 27.4 ppmPage 55 of 313
Page 1 and 2:
Chem 155 Unit 1 Page 1 of 313Chemis
Page 3 and 4: Chem 155 Unit 1 Page 3 of 3131 Over
Page 5 and 6: Chem 155 Unit 1 Page 5 of 31312 Int
Page 7 and 8: Chem 155 Unit 1 Page 7 of 3131 Over
Page 9 and 10: Chem 155 Unit 1 Page 9 of 3131.1.2
Page 13 and 14: Chem 155 Unit 1 Page 13 of 3131.3 V
Page 15 and 16: Chem 155 Unit 1 Page 15 of 3131.5 S
Page 17 and 18: Chem 155 Unit 1 Page 17 of 313Confi
Page 19: Chem 155 Unit 1 Page 19 of 3131.5.4
Page 24 and 25: Chem 155 Unit 1 Page 24 of 3131.7 V
Page 34 and 35: Chem 155 Unit 1 Page 34 of 313See a
Page 36 and 37: Chem 155 Unit 1 Page 36 of 3136. Yo
Page 38 and 39: Chem 155 Unit 1 Page 38 of 3131.10.
Page 40 and 41: Chem 155 Unit 1 Page 40 of 3134. Wh
Page 42 and 43: Chem 155 Unit 1 Page 42 of 3137. Ho
Page 44 and 45: Chem 155 Unit 1 Page 44 of 313In ge
Page 46 and 47: Chem 155 Unit 1 Page 46 of 3131.13
Page 52 and 53: Chem 155 Unit 1 Page 52 of 3131.15
Page 56 and 57: Chem 155 Unit 2 Page 56 of 3132 Pro
Page 58 and 59: Chem 155 Unit 2 Page 58 of 313error
Page 60 and 61: Chem 155 Unit 2 Page 60 of 313For a
Page 62 and 63: Chem 155 Unit 2 Page 62 of 313Obvio
Page 64: Chem 155 Unit 2 Page 64 of 313The p
show all

Chemistry 155 Introduction to Instrumental Analytical Chemistry

Create successful ePaper yourself

Delete template?

Save as template?