Question

The water-soluble vitamins niacinamide (a neutral com- pound), riboflavin (a neutral compound), niacin (an anion), and thiamine (a cation) were separated by micellar electrokinetic chromatography in 15mMborate buffer (pH8.0)with 50mMsodium dodecyl sulphate. The migration times were niacinamide (8.1min), riboflavin (13.0min), niacin (14.3min), and thiamine. What would the order have been in the absence of sodium dodecyl sulphate? Which compound is most soluble in the micelles?

Short answer

The thiamine is eluted last as it would be the most soluble.

Step-by-step solution

Definition of water soluble vitamin

Vitamin A, D, E and K are fat-soluble vitamins. Water-soluble vitamins are not stored in our body as its excess gets excrete through the urine. Therefore, these vitamins need to be replenished constantly. Vitamin B and C are water-soluble vitamins.

Task of soluble vitamin

In the task niacinamide riboflavin, niacin and thiamine were separated by micellar electrokinetic chromatography. We need to state the order in the absence of sodium dodecyl sulphate and determine which compound would be the most soluble in the micelles.

Soluble compounds

Niacinamide (neutral)

Riboflavin(neutral)

Niacin (anion)

Thiamine (cation)

Sodium dodecyl sulphate is an anionic surfactant in the absence of the compound we would that be the order: Cation<neutral<anion

Which in our case means: Thiamine < riboflavin =niacinamide<niacin

Consider thiamine to be eluted last as it would be the most soluble.