Skoog, Holler, and Crouch, Principles of Instrumental Analysis, 7th Ed. Page 4.
Skoog, Holler, and Crouch, Principles of Instrumental Analysis, 7th Ed.
http://www.microscopy.fsu.edu/primer/digitalimaging/concepts/images/photomultiplier.jpg
Rubinson, K.A. and J.F. Rubinson, Contemporary Instrumental Analysis. 2000, Upper Saddle River: Prentice Hall.
Skoog, Holler, and Crouch, Principles of Instrumental Analysis, 7th Ed.
Skoog, Holler, and Crouch, Principles of Instrumental Analysis, 7th Ed.
Skoog, Holler, and Crouch, Principles of Instrumental Analysis, 7th Ed.
Skoog, Holler, and Crouch, Principles of Instrumental Analysis, 7th Ed.
Dong, M.W., Modern HPLC for Practicing Scientists. 2006, Hoboken, NJ: Wiley. 286.
Skoog, Holler, and Crouch, Principles of Instrumental Analysis, 7th Ed.
Skoog, Holler, and Crouch, Principles of Instrumental Analysis, 7th Ed.
Fluorimeter
Skoog, Holler, and Crouch, Principles of Instrumental Analysis, 7th Ed.
Spectrofluorimeter
4-fluoro-7-nitro-2,1,3-benzoxadiazole
Ciriacks Klinker and Bowser, Anal. Chem. 2007, 79, 8747-8754
Ciriacks Klinker and Bowser, Anal. Chem. 2007, 79, 8747-8754
Fluorescein-5-isothiocyanate (FITC)
Johnson and Landers, Electrophoresis, 2004, 25, 3513-3527
Figure 18-3 Skoog, Holler, and Crouch, Principles of Instrumental Analysis, 7th Ed.
Rubinson and Rubinson, Contemporary Instrumental Analysis
Rubinson and Rubinson, Contemporary Instrumental Analysis
Skoog, Holler, and Crouch, Principles of Instrumental Analysis, 7th Ed.
The Big Problems with IR and Raman Problem IR 1. Water absorbs a lot of IR radiation (think microwave!) and thus gives large background signal 2. Most solvents (and solid matrices) absorb a lot of (total) IR too, which heats up the sample 3. Signals for specific transitions are small due to low probabilities of individual transitions and short path length 4. Noise is high because of temperature fluctuations in thermal detectors
Raman 1. Most molecules do not exhibit strong Raman scattering (low S in S/N)
Solution
UV-Vis and IR Spectra of Caffeine
Absorbance (A.U.)
0.25 0.20 0.15 0.10 0.05 0.00 200
400
600
Wavelength (nm)
800
Rubinson, K.A. and J.F. Rubinson, Contemporary Instrumental Analysis. 2000, Upper Saddle River: Prentice Hall.
Eight Key Points of Comparison of Instrumental Methods 1. Selectivity – What does the instrument respond to? Universality vs. specificity 2. “Sensitivity” – What is the detection limit (LOD)? 3. Speed of analysis (throughput) 4. Cost per analysis 5. Precision (%RSD) – How similar are the results for repeated analysis of the same sample? 6. Accuracy – How close is your result to the ‘true’ answer? 7. Reproducibility – If you analyze a sample today, and the same sample one year from now, how close will the results be? 8. Compatibility – Given the chemistry of the molecule, does it make sense to use method X to analyze analyte Y?
