Analysis

Question 1

what is extraction used for

Answer 1

to separate drug molecules

involves selective removal of components of a gas/liquid/solid mixture by contact of the mixture with a second phase

Question 2

what is partitioning

Answer 2

differing solubilities of components in immiscible solvents

depends on distribution`

Question 3

what is adsorption

Answer 3

based on selective adherance of components of liquid or gaseous mixture to surface of a solid phase
depends on distribution

Question 4

gas cromatography

Answer 4

separates volatile compounds that may differ in bp by less than half a degree
used analytically and practically
supports fractional distillation and separation/purification on a small scale

Question 5

gas chromatograpgy process

Answer 5

mixture is vapourised and carried along a column by inert flowing gas
gaseous mixture is mobile phase
column is packed with a solid, finely divided substance, the surface of which is coated in a low volatile liquid to serve as the stationary phase
components move at different rates and are separated
physical process involved is partitioning

Question 6

feature of gas chromatographs

Answer 6

carrier gas supply, pressure-reducing valve, dessicant, fine-control, flow meter, heted injection part, column, oven

Question 7

what is retention time

Answer 7

time taken for component to pass from injection site to detector

Question 8

factors affecting retention time

Answer 8

nature of liquid phase
length of column
temperature of column
rate of gas flow

Question 9

liquid coating

Answer 9

liquid is coated on the solid support by dissolving the liquid in a suitable low-boiling solvent and mixing the solution with a solid
low bp solvent is then evaporated, leaving solid granules evenly coated and the column is filled with granules

Question 10

what are capillary columns

Answer 10

long columns with small diameters
liquid is coated directly on inner walls of tubing
very efficient but quite expensive

Question 11

column efficiency

Answer 11

increases with increasing path length and decreases with increasing diameter
diameter of column effects band width

Question 12

retention times

Answer 12

shorter with high temps because gas solubility in liquids decreases with increasing temperature
gives quicker separation but lower resolution

Question 13

GC-MS-MS

Answer 13

relies on volatile molecules being separated in conventional capillary GLC and then output signal of first MS is input for soft ionisation, leading to fragmentation in second MS