And though 'blood' wasn't given the prominent status as we thought it'd be, i guess i did well.
Running to Biochem practical hall from there was easier than settling between intuition and lack of knowledge in there.
The solution 14 was clean, clear, colourless. Molisch's - check.
Iodine test:
3 mL of solution was taken, one drop of iodine was added. Deep colour was observed. And i wrote the observation. And then it struck! Doesn't that mean it's starch? But what about the clarity of solution?
Ah! That horrible moment in the chemistry lab when the solution back stabs you.
Confusion, confusion! And then i proceeded as if the answer was negative (not filling in the answer script, btw)
Benedict's - answers!
(Well, starch could have glucose units that drop down from the main chain)
osazone - no. Nothing in 5 minutes. Around 20 minutes and there's slight crystal formation, i guess (the kind i used to get in lactose/maltose, not enough to be transferred to slide)
ok. Barfoed's - no answer.
Ok. I'm gonna settle with starch, I said to myself. Hydrolysis, ok. Then Benedict's, obviously positive. Seliwanoff's - negative. Hmmm. Not Sucrose either. But what about the transparent solution? Looking at others on the way to osazone formation, i could see clearly white solutions of starch. What the?
Iodine test again! Same deep colour. Not exactly violet. Sort of black. Ok, that's what i got in 12th standard during the biology practicals. This is it. Starch!
And i still don't know if it was indeed starch or not. I even tried tasting (yes, that's against lab rules, but this is carbohydrates we're dealing with) and i had taken so little for the fear of cyanide poisoning that i couldn't be sure it was not sweet.
Professor Mahadeva sir comes for viva. And he takes my paper and starts asking about starch..
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