Gas Chromatography Refractive Index Polarimetry Next Lecture: Lecture Problem 8 Due Next Thursday:...
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Transcript of Gas Chromatography Refractive Index Polarimetry Next Lecture: Lecture Problem 8 Due Next Thursday:...
Gas ChromatographyRefractive IndexPolarimetry
Next Lecture: Lecture Problem 8 DueNext Thursday: Quiz 7 in LectureNext Week’s Office Hours: Tuesday from 3 to 5 pm!
This week in lab:• Ch 9 Final Report Due• Synthetic #2 PreLab Due
Next week in lab:Synthetic #1 Final Report Due
Lecture 24
Nutmeg Oil GC-MS Data
Mass Spectrum of A
M+ at 192
Compound is:
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O
O
OCH3
Allyl methoxybenzodioxoleFW = 192
Chromatography
TLC & Column Chromatography• Stationary phase: silica gel (polar)• Mobile phase: organic solvent(s) (varying polarity)• Separation: based on differences in polarity of compounds
Gas Chromatography• Stationary phase: can be polar or nonpolar (choice of column) Instrument Room GC uses a nonpolar stationary phase• Mobile phase: helium gas!• Separation: based on boiling points and/or size of compounds• Can vary the temperature - allows for better separation of complex mixtures (low-boiling vs high-boiling components) • Flame ionization detector (FID)• Chapter 18 in Lab Guide
Gas Chromatography
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FID Detector
Gas Chromatography
Capillary column
Injection site
Control panel
Gas ChromatographyPlotter
Gas Chromatography
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Info from chromatogram:• # of components in sample• Retention time of each component• Area of each signal - calculate % of each component in sample
Refractive Index
• An intrinsic property of a liquid compound• Defined as the ratio of the speed of light through a vacuum tothe speed of light through the liquid
Operational instructions are given in Chapter 20.
Refractive Index
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Figures taken fromWilliamson, Minard & MastersMMOE, 5th edition
Ideal reading
Polarimetry• To determine the optical activity of a compound. Watch video
at http://www.colby.edu/chemistry/OChem/DEMOS/Chirality.html• Calculate the specific rotation of a chiral compound; seeChapter 19 of the Lab Guide
Cell for sample solution
Digital display -results