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MCAT lab techniques
lab techniques OC, Biochem, DNA
Term | Definition |
---|---|
liquid-liquid extraction | shaken and separated like like (polar-polar eg); salt from base+acid in aqueous solution;WB&COOH=anionic salt; phenols w/ NaOH diluted; NaHCO3 no phenol yes COOH |
principle of extraction | salts are preferred for aqueous phase |
thin layer chromatography | polarity & capillary action; results UV light maybe & Rf = substance move/solvent final move |
polar stationary phase of TLC | solid-liquid with SiO2 absorbent; developing/running |
Column chromatography | SiO2 gel gravity filtration with polar reacting with gel/TLC plate; least polar comes out first |
Ion exchange chromatography | gravity filtration with ionic resins, or salts, where the + charged will flow through and replace the Na+ for example; what does not stick, neutral and - out first; pI value of importance; pI values above pH first to elute |
High Performance Liquid Chromatography (HPLC) | high pressure forces mobile through stationary = efficient speed, no gravity; chromatogram; silica gel |
reverse phase HPLC | nonpolar is silica gel binds nonpolar; mobile is polar |
size exclusion chromatography | porous polymer beads; small travel more distance end up last |
affinity chromatography | stationary phase solid resin, like with Ab; binding with Ab goes gravity bottom; no centrifuge using beads magenetized; commercialized specificity; N/C affinity tag |
gas chromatography | mobile gas phase & stationary liquid phase; volatility |
distillation | breaking bonds; making bonds; BP |
Simple distillation | impurities miniscule; BP |
Fractional distillation | column packed with wire/beads/cotton; vapor impurities at bottom; pure at top |
spectroscopy, general | ground state to excited state to ground =emission & record |
Mass spec | high vacuum ionization; magnetic field & flight path change; r=mv/qB; abundance y axis & M/e x axis; good for isotopes; Br/Cl |
UV Visible spec | transition metal d orbital & conjugation pi bonds; wavelength related to amt of conjugation; absorption and emission opposite red-green;orange-blue;vio-yell |
IR spec | wavelength 2.5 to 20um; excited vibration; wavenumber is 1/wavelength=v/c; E=hv; RCOR 1700; C=C 1650; OH 3600-3200; RCCR 2260-2100; CH 3300-2700; N low O |
H NMR spec, general | equivalent Hs |
spin-spin splitting | H NMR; Hs not same group interact; protons in field interact with molecule proton; n + 1 & n=neighboring Hs; if 2 neighboring Hs interfere then 3 splits; singlet for 0 doublet for 1, triplet, quartet, quintet, sextet |
NMR integration | area under curve related to number of Hs causing the spike |