Paper chromatography can be used to separate the individual amino acids formed when tripeptides are hydrolysed. One molecule of a tripeptide produces three amino acid molecules when hydrolysed. A student is asked to identify the amino acids formed from the hydrolysis of three different tripeptides, A, B and C, using paper chromatography. [Figure 2.1] shows the results of the student's chromatography experiment. [Figure 2.1] The individual amino acids can be identified from their R_f values. R_f = distance travelled by the amino acid spot / distance travelled by the solvent front

1. (a)Suggest why each sample is applied to the chromatography paper using a thin capillary tube rather than a dropping pipette.[1]
2. (b)Suggest why it is necessary to spray a developing agent over the chromatography paper before the chromatogram can be analysed.[1]
3. (c)Table 2.1 shows R_f values for some amino acids in the solvent used in [Figure 2.1]. [Table 2.1] Use the data in Table 2.1 to identify the amino acids in tripeptide A.[2]
4. (d)Suggest why the hydrolysed sample of B produces only two spots.[1]
5. (e)(i)Two of the spots from the hydrolysed sample of C overlap. State the reason for the overlap.[1]
6. (e)(ii)Suggest an improvement to the method that would allow the overlapping spots to be distinguished clearly.[1]

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