Term
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Definition
| The separation of complex materials |
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Term
| How is abundance shown on the chromatograph? |
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Definition
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Term
| How is retention time shown on the Chromatograph? |
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Definition
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Term
| How is concentration shown on the chromatograph? |
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Definition
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Term
| What is the Mobile Phase? |
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Definition
| Molecules dissolved in the solvent |
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Term
| What is the stationary phase? |
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Definition
| Molecules adsorbed on the solid packaging |
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Term
| What determines the stationary phase? |
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Definition
| The polarity of molecules |
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Term
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Definition
| A shared pair of electrons that are not shared equally |
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Term
| What is electronegativity |
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Definition
| The ability of an atom to attract the electron density towards itself in a covalent bond |
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Term
| If Charge separation increases, Polarity _______? |
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Definition
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Term
| Give examples of polar molecules |
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Definition
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Term
| Give examples of non-polar molecules |
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Definition
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Term
| Chromatography only works if the peaks are properly ________? |
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Definition
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Term
| What is retention time used to identify? |
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Definition
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Term
| Wht are different affinities caused by? |
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Definition
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Term
| Is the retention time of the mobile phase long or short? |
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Definition
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Term
| Is the retention time of the stationary phase long or short? |
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Definition
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Term
| What does HPLC stand for? |
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Definition
| High performance liquid chromatography |
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Term
| What state of matter is the mobile phase in HPLC? |
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Definition
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Term
| In reversed phase chromatography, what is the stationary phase and why is it used? |
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Definition
| Silica (SiO2) Used because it's easy to make into small particles |
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Term
| What is used instead of silica for the stationary phase in reversed phase chromatography when polar molecules are being analysed? |
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Definition
Octadecylsilane (ODS)
Chemically modified silica |
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Term
| Why is UV absorption spectroscopy universal? |
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Definition
| Everything will absorb UV light at a short enough wavelength |
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Term
| Name some applications of HPLC |
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Definition
Identifying drugs
Vitamin levels in food
Sugars in honey and fruit juice
Caffeine levels in drinks |
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Term
| What are the structures in a column chromatographer? |
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Definition
-Stainless steel tube packed with solid - stationary phase
-Inlet
-Detector |
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Term
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Definition
| The time taken for a component to reach the detector? |
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Term
| What data gives qualitative information and what gives quantitative information? |
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Definition
Qualitative - time
Quantitative - area under peak |
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Term
| What does time give information on? |
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Definition
| The identity of the substance |
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Term
| What does the area under the peak measure? |
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Definition
| The abundance of the substance |
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Term
| What makes molecules move quickly or slowly? |
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Definition
Move quickly - if dissolved in solvent
Move slowly - if adsorb onto stationary phase |
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Term
| What determines how much a molecule dissolves and adsorbs? |
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Definition
The polarity of it
- different affinities for mobile and stationary phase |
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Term
| Why do polar molecules dissolve in the solvent? |
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Definition
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Term
| Why do non polar molecules adsorb to packing? |
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Definition
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Term
| What does it mean if the graph is well resolved? |
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Definition
| The peaks are separate with clear gaps |
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Term
| Why are small particles of stationary phase used? |
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Definition
| Increases surface area molecules can adsorb onto |
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Term
| What is the disadvantage of using SiO2 as the stationary phase? |
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Definition
| Very polar so polar molecules stick there for a long time |
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Term
| How is ODS modified to make it less polar? |
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Definition
| Coated with non polar hydrocarbons to balance charge |
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Term
| What structures does a HPLC chromatographer have? |
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Definition
-Stainless steel tube packed with stationary phase
-Solvent reservoir and pump
-Mobile phase
-Injection valve
-Detector |
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Term
| What is used as a mobile phase in HPLC? |
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Definition
| A solvent more polar than the stationary phase |
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Term
| Which is the most and least polar out of methanol, water and acetonitrile? |
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Definition
Most - water
methanol
Least - acetonitrile |
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Term
| What is the purpose of a loading loop? |
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Definition
| So the solvent's path isn't disrupted by analyte |
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Term
| What is used as a detector and why? |
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Definition
| UV absorption spectrometry, because it's universal |
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Term
| What is the mobile phase in gas chromatography? |
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Definition
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Term
| What is the stationary phase in gas chromatography? |
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Definition
-Packed column
-Capillary column |
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Term
| What is a packed column in gas chromatography like? |
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Definition
-Stainless steel
-1m long
-5mm in diameter
-Particles of solid packed inside |
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Term
| What is a capillary column in gas chromatography like? |
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Definition
-Glass
-3m long
-1/10mm in diameter
-Plastic (polyimide) coating
-Stationary phase layer on inside of tube |
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Term
| Where does gas chromatography take place? |
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Definition
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Term
| What does increasing the temperature when gas chromatography is taking place do? |
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Definition
| Extends the range of things analysed |
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Term
| What stationary phases are used for gas chromatography and what for? |
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Definition
Squalene - non polar, used for hydrocarbons, oils
Diethylene Glycol succinate - moderately polar, used for fatty acids, methyl esters
Polyethylene glycol - polar |
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Term
| How polar should the stationary phase be in relation to the sample? |
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Definition
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Term
| How is gas chromatography carried out? |
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Definition
-Sample injected into vapourisation chamber and moves down with carrier gas
-Substance added with analyte to get internal standard
-Concentration of unknown is determined by comparing peak areas with peak area on internal standard |
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Term
| What is the detector in gas chromatography? |
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Definition
| Flame ionisation detector |
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Term
| How does a flame ionisation detector work? |
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Definition
-Ions burn in different ways
-detected as electric current |
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Term
| What are the advantages of a flame ionisation detector? |
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Definition
-Can measure low concentrations
-Will detect anything that burns with a good sensitivity |
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Term
| What are the applications of gas chromatography? |
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Definition
-GS-MS (gas spec - mass spec)
-Disease diagnosis
Analysing:
-Pesticidal residue
-Molecules with low molecular weight - volatile
-Alcohols
-Hydrocarbons
-Fatty acids from triglyceride lipids |
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Term
| How can gas chromatography be used to diagnose diseases? |
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Definition
| By identifying compounds in breath, body fluids |
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