Quiz 2: High Pressure Liquid Chromotgraphy

Question 1

HPLC

Answer 1

technique of quantitative and qualitative analysis of organic mixtures
-room temp
-can handle high molecular weight/temp-sensitive samples

Question 2

whats the general rule when picking HPLC or GC

Answer 2

GC is used unless the sample is not volatile enough/ decomposes on heating

Question 3

What can HPLC handle better than GC

Answer 3

-handle ANY molecular weight sample
-some detectors are only available when using HPLC
-preparative separation of an organic compound from an impure mixture

Question 4

Preparative separation vs Analytical separation

Answer 4

Preparative:
-goal: to purify usable amounts of one particular component in a mixture
-run on anywhere 0.1g-kg
-cleaning up reaction mixtures
-isolating natural products from complex hosts

Analytical:
-run on micrograms

Question 5

moving phase

Answer 5

liquid
-common solvent (h2o, methanol)

Question 6

stationary phase

Answer 6

fine particles of silica (Si-O_H)
dense & high resistance

Question 7

reverse phase

Answer 7

stationary: nonpolar
mobile: polar

Question 8

general behavior of organic sample

Answer 8

a) the more polar the organic, the faster it will move through the column (shorter retention time)

b) raising the percentage of methanol will speed up the movement of the less polar components compared to the more polar components
-raising the percentage of water will have the opposite effect