OC4: separation techniques

Question 1

polyacrylamide gel electrophoresis (PAGE)

Answer 1

uses an electrolytic cell to separate compounds based on size or charge

Question 2

native PAGE

Answer 2

proteins are placed in the polyacrylamide gel without any modification; they retain their native structure and are separated based on size and charge

Question 3

SDS PAGE

Answer 3

a detergent, sodium dodecyl sulfate (SDS), is used to denature the proteins; this gives them a uniform charge and separation is based on size alone

Question 4

isoelectric focusing

Answer 4

uses a gel with a pH gradient where the anode is acidic (positively charged) and the cathode is basic (negatively charged); The point at which the protein stops in the gel corresponds with its pI

Question 5

immiscible solvents

Answer 5

solvents unable to be mixed together; separates polar and NP compounds

Question 6

aqueuous phase

Answer 6

polar layer (bottom layer)

Question 7

organic phase

Answer 7

nonpolar layer (top layer)

Question 8

distillation

Answer 8

used to separate substances in the liquid phase based on their boiling points

Question 9

distillate

Answer 9

liquid with the lowest boiling point, which is vaporized and collected first

Question 10

simple distillation

Answer 10

used when the boiling points for the liquids are 25°C apart from one another and both are under 150°C

Question 11

fractional distillation

Answer 11

used when the boiling points for the liquids are LESS THAN 25°C apart from one another and both are under 150°C

Question 12

vacuum/column distillation

Answer 12

used with BPs are above 150°C; system pressure is decreased, therefore lowering BPs

Question 13

stationary phase

Answer 13

solid

Question 14

mobile phase

Answer 14

liquid or gas running through the stationary phase

Question 15

normal-phase paper chromatography

Answer 15

uses a polar cellulose paper as the stationary phase and a nonpolar solvent as the mobile phase; the further UP a sample travels, the more NONPOLAR it is

Question 16

retention factor (Rf)

Answer 16

(Distance sample moved) ÷ (Distance mobile phase moved)

Question 17

thin-layer chromatography

Answer 17

stationary phase is polar (silica gel), and the mobile phase is nonpolar

Question 18

reverse-phase paper chromatography

Answer 18

uses a nonpolar stationary phase and polar mobile phase; the further UP a sample travels, the more POLAR it is

Question 19

gas chromatography

Answer 19

uses a column to separate volatile compounds that are vaporizable; can be used to separate racemic mixtures

Question 20

HPLC (high-pressure liquid chromatography)

Answer 20

uses a liquid mobile phase

Question 21

column chromatography

Answer 21

separates compounds based on charge, affinity, and size using a column lined with silica or alumina beads as a stationary phase

Question 22

ion-exchange chromatography

Answer 22

beads are coated with a charged substance that attracts compounds with the opposite charge

Question 23

affinity chromatography

Answer 23

beads are coated with a substance that the compound of interest has a high affinity for

Question 24

size-exclusion chromatography

Answer 24

contains porous beads that slow down the flow of smaller compounds and allows larger compounds to elute first