F324 Chromatography & Spectroscopy HW (MS) 
1.	(i)	adsorption 
ALLOW partition OR adsorbtion
IGNORE solubility OR desorption
DO NOT ALLOW absorption
1
(ii)	measure how far each spot travels relative to the solvent front or
calculate the Rf value 
	compare Rf values to those for known amino acids 
ALLOW compare Rf values to database
ALLOW compare to known amino acids
DO NOT ALLOW retention times for first mark, but the 2nd mark would be available as  ECF
ALLOW alternative approach: on the same plate compare position of spots  with known amino acids 
2
(iii)	(amino acids won’t separate because) similar compounds have
similar Rf (values) 
ALLOW spots often overlap OR don’t (fully) separate
ALLOW they have similar Rf (values) or similar adsoptions or similar retention times ECF to (ii)
1
[4]
 
2.	(i)	Accept paper, column or thin-layer chromatography	1
(ii)	The Rf value	1
(iii)
	1
[3]

3.	(a)	(i)	Retention time	1
(ii)

(or mirror image)	1
(b)	Partition	1
[3]
4.	gas/liquid chromatograph separates the tripeptides (1)
	mass spectrometer produces a distinctive fragmentation pattern (1)
	identification by computer using a spectral database (1)	3
[3]

5.	IR
	Similarities
Any 2 of the following three peaks (must give the quoted range)
peak corresponding to OH in all three(3230 – 3550 cm–1) (1)
peak corresponding to NH in all three(3100 – 3500 cm–1) (1)
peak corresponding to CO in all three (1000 – 1300 cm–1) (1)	2 max
	Differences
only shown in the fingerprint region (1)	1
	Mass Spec
	similarities
Mr (75)/ base peak will be the same (1)	1
M + 1 peak same (1)	1
	Differences
Fragmentation pattern may show differences between isomers
/ specific example, eg CH3+ at m/e 15 (1)	1
		(MAX 5)
	QWC
Use of any two terms from: functional group / amino group /
hydroxy group / fingerprint / fragmentation / fragment ion(s) /
base peak or molecular ion / M + 1 peak / m/e	1
[6]

6.	δ value / chemical shift gives the ‘type’ of proton /
chemical environment (1) AW
example quoted from data sheet (1)
	number of peaks gives the number of different types of proton /
chemical environments (1)
	relative / ratio of (1)
peak areas gives the number of protons (of each type) (1)
	splitting gives number of neighbouring / adjacent protons (1)
	description of n + 1 rule / example of doublet, triplet or quadruplet
showing 1, 2 and 3 protons neighbouring (carbon) atom (1) AW
	D2O can be used to identify OH groups (1)
ANY 7 marks out of 8	7
	Quality of written communication mark for correct use and
organisation of at least two of the following technical terms:
proton, environment, singlet (doublet etc.), ppm, equivalent,
chemical shift, splitting, labile, integration	1
[8]

7.	(i)	the peak is due to the CH3CO- group (1)
	not split, so next to a C with no protons / has no neighbouring proton /
δ value is in the range 2.0 – 2.9 (1)	2
(ii)	adjacent to a C with three protons / to a CH3 (1)	1
(iii) and (iv)	3

mark any additional incorrect peaks first
[6]

8.	(i)

	splitting:
doublet (1)
quartet (1)
ignore any other peaks
	position:
doublet peak is at ~1.4 and
quartet peak is at ~4.3 (1)
allow ecf from one incorrect splitting pattern
	areas:
1 and 3 on the correct peaks
(or either way round as ecf if any errors above) (1)	4
(ii)	4 (1)
OH/labile protons now visible AW (1)	2
[6]
 
9.	(a)	low boiling point / easily turns to a gas AW (1)	1
(b)	2,4-dinitrophenylhydrozine / 2,4-DNP(H) / Brady’s reagent (1)
	purify/recrystallise the product/solid (derivative) (1)
	measure the melting point /mp (1)
	compare the result with data book/known values (1)	4
[5]