Exp 5.4: Carbohydrates (TLC)

Question 1

purpose of TLC

Answer 1

to separate products in the acid (glucose) and enzymatic (glucose, maltose, dextrin) hydrolysates of starch and glycogen

Question 2

polarity of the stationary phase
(phase of silica gel)

Answer 2

normal phase

Question 3

stationary phase used

Answer 3

silica gel

Question 3

mobile phase used

Answer 3

solvent systems

Question 4

which is more polar: silica gel or solvent systems

Answer 4

silica gel

Question 5

silica gel used

Answer 5

normal phase siliga gel G

Question 6

meaning of G in normal phase silica gel G

Answer 6

gypsum (CaSO4)

Question 7

what is present on the surface of normal phase silica gel G

Answer 7

-OH groups

Question 8

physical interactions involved

Answer 8

hydrogen bonding or dipole-dipole (polar) interaction

Question 9

direction of solvent front

Answer 9

ascending

Question 10

principle involved in separation based on physical states of the stationary and mobile phases

Answer 10

adsorption

Question 11

separation of the carbohydrates in the hydrolysate will depend on their ________

Answer 11

polarity

Question 12

solvent system:
reagents and ratio

Answer 12

acetonitrile: water
(85:15)

Question 13

concentration of EDTA and sulfuric acid used

Answer 13

0.3% 1-naphthyl EDTA and 5% sulfuric acid in MetOH

Question 14

visualizing agent

Answer 14

p-anisaldehyde

Question 15

color of spots when visualizing agent (p-anisaldehyde) is used

Answer 15

blue/ blue-green/ green

Question 16

basis of visualizing agent (p-anisaldehyde)

Answer 16

based on complex with the sugar

Question 17

T/F:
the less -OH groups, the more polar the sugar is more adsorbed on normal phase silica gel

Answer 17

false
more -OH groups = more polar

Question 18

Arrange from most polar to least:
maltose, dextrin, glucose

Answer 18

glucose > maltose> dextrin