UF PHA6936 FINAL EXAM PREP NEWEST ACTUAL

UF PHA6936 FINAL EXAM PREP NEWEST ACTUAL /

QUESTIONS WITH CORRECT ANSWERS

Stokes scattering - ----Answers---emitted photons end up at a higher vibrational energy state or wavelength then the original

anti-Stokes scattering - ----Answers---photons can end up at a lower energy state

Disadvantages to Raman - ----Answers---weak signal inhibited when analyzing naturally fluorescent substances mixtures are difficult to analyze

Surface Enhanced Raman Spectroscopy (SERS) - ---- Answers---sample is adsorbed onto a metal surface prior to analysis leading to a higher signal

Advantages of Raman - ----Answers---rapid no sample prep detect through some packaging portable nondestructive quantitative and qualitative

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Retention - ----Answers---amount of time spent in the stationary phase versus the mobile phase

Equation for Retention - ----Answers---k= t(retained peak) - t(non-retained peak)/t(NR)

Resolution - ----Answers---space between peaks

What resolution is desirable to avoid possible interference of one peak with another? - ----Answers---1.5

What is resolution related to? - ----Answers---Efficiency, selectivity, and retention

Selectivity - ----Answers---how well components can be distinguished from one another

Efficiency - ----Answers---number of theoretical plates needed for separations

Components in a GC - ----Answers---injector, columns, and detectors

Injectors - ----Answers---heated to allow flash vaporization of the sample following injection, generally automated process, 1-3 micoliters vaporized

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Split Injector - ----Answers---septum purge remains open, allowing flow of carrier gas to minimize any potential extraneous peaks that could result from the septum itself, moves the sample through the column or the split vent, amount of sample reaching the column is dependent on the ratio

Spitless Injection - ----Answers---split vent value is closed and carrier gas and sample flow through the inlet to the column allowing the full volume to be deposited onto the column, low concentration samples

Pulsed-spitless Injection - ----Answers---spiltless mode proceeds by injecting larger volume of sample and increasing inlet pressure for a short period of time, which rapidly properls the sample onto the column

Advantages of Pulsed-spitless Injection - ----Answers---for more volatile compounds so they don't get lost to the split vent also useful for thermally labile sample components

Disadvantages of pulsed-spitless Injection - ----Answers--- could overwhelm the inlet and cause flashback contaminating the gas supply lines and septum

Derivatization for GC - ----Answers---done to alleviate volatility and stability issue and improve chromatography

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Acetylating Agents for GC - ----Answers--- Pentafluoropropionic anhydride (PFPA), and trifluoroacetic anhydride (TFAA), and acetic anhydride (AA), used for amines, amides, thiols, phenolic, alcohol and aromatic rings More stable than silyl derivatives

Reagents used for Derivatization - ----Answers---Silylating and Acetylating

Silyating Agents for GC - ----Answers---BSTFA to derivatizing compounds that contain carboxylic acid, amide, phenolic, or OH groups highly volative and sensitive to moisture

Drugs to use Silyating Reagents On - ----Answers---9- tetrahydrocannabinol, lorazepam, and genzoylecgonine

Drugs derivatized by Acetylating Agents - ----Answers--- amphetamine, MDMA, and methylphenidate

Type of Detectors for GC - ----Answers---Electron capture detectors (ECD) Flame Ionization detectors (FID) Thermal Conductivity detectors (TCD) Nitrogen-Phosphorus Detector (NPD) Mass Spectrometers (MS) Infrared spectrophotometers (IR)

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