thin layer chromotagraphy

Question 1

what does th tlc use as the stationary phase

Answer 1

a chromatography plate consisting of plastic sheet coated with silicon dioxide

Question 2

why do we use plastic

Answer 2

as they can be cut to the required size using scissor

Question 3

what do we do with a spot

Answer 3

a small spot contain the mixure of amino acids to be separated is placed on a line using a capillary tube and placed in a tank with solvent

Question 4

why is a lid place on the tank

Answer 4

so the indide is saturated with solvent vapour

Question 5

what do we allow to rise

Answer 5

the solvent carrying the amino acids with it

Question 6

how does the lagging of amino acid depend on

Answer 6

the affinity for the solvent compared to the affinity to the stationary phase dependent of the intermolecular forces between the two

Question 7

what jhappens when the solvent nearly reaches the top

Answer 7

the plate is removed and the solvent front is marked immediately

Question 8

as amino acids are colorless what do we use

Answer 8

spray the plate using ninhydride which react to form a purple compound or use uv light

Question 9

what do we calculate next

Answer 9

rf values for the amino acids that have moved up the p[late

Question 10

what are the advantages of thin layer chromotagraphy compared to paper

Answer 10

it runs faster
smaller amounts of mixures can be seperates
spots usually spread out a lot less
plates are more robust

Question 11

what does colum chromotagraphy use

Answer 11

a powder such as silica or aluminium oxide as the stationary phases

Question 12

what is done to the powder

Answer 12

it is packed into a column

Question 13

and what happens to the solvent

Answer 13

it is added on the top which included the sample eleunt

Question 14

what happens to the eleunt

Answer 14

it runs down the colum and the component of the mixure move at different rates

Question 15

what can be done to these smaples

Answer 15

they can be collected seperately and the time taken to travel through the column

Question 16

how do we get better seperation

Answer 16

more than one eleunt can be used

Question 17

why is it an advantage to use this method to seperate

Answer 17

a large amount can be seperated and collected including the pure components

Question 18

what is the stationary phase in the gas chromotachraphy

Answer 18

powder coated with oil packed or coated in a long capillary tube which is coiled and placed in an overn

Question 19

what is the mobile phase

Answer 19

an inert gas such as helium

Question 20

what happens to the smaple

Answer 20

it is injected and carried along by the gas and the mixure seperates in accordance to its retetnaion to stationary phase

Question 21

what does this mean

Answer 21

hte components leave the column at different times so have different retetnion times

Question 22

what is done to the dat

Answer 22

it is presented onto a graph with each peak proportional to the amount of component

Question 23

what is a strenght of using gas chromotagraphy

Answer 23

it is so sensitive it can seperate minute traces in food and crude oil,drug taking

Question 24

how is the identification of a component done

Answer 24

by matching its retention time with that of a known substance under the same conditions

Question 25

what does gcms stand for

Answer 25

gas chromotagraphy mass spectroscopy

Question 26

what is it

Answer 26

two techniques in one

Question 27

what is the mass spec used for

Answer 27

to detect the compound molecular formula or its fragmented pattern

Question 28

how does it work

Answer 28

after it has come out of the gas chromotagraphy colum and retention time noted it is fed automatically into the colum