PREPARATION OF STANDARD VITAMIN C CURVE

Place 100mg ascorbic acid in 100ml standard flask and make it up to the mark[1mg/ml],prepare the standard curve of the vitamin c by adding the required weight of the ascorbic acid to the extracting solvent to make 100ml..
Dilute 1ml of the standard mixture to 10ml with 4% TCA[trichloroacetic acid] solution..add 0.75g acid washed norit and shake vigorously and filter...place 2ml of each filtrate in two test tubes,add 1 drop of 10% thiourea solution and 0.5ml of 2.4--DNP[dinitrophenylbenzene] reagent.....place the two test tubes in a water bath at 37degree celcius for 3hours and then place it in a beaker of ice water ..then add 25ml of 98% tetraoxosulphate acid[H2SO4] in dops form the burette in 1 min...then take the absorbance after 30 minutes using jenway 6051 calorimeter..then plot the graph of absorbance against concentration to obtain standard ascorbic acid curve...

SAMPLE PREPARATION
Extract 2.0g of milled sample with 25ml of 0.1% oxalic acid,centrifuge the mixture and transfer the supernatant into a 50ml standard flask..wash the residue 2 times with 10ml of 1.0 oxalic acid,pool it together and make it up to 50ml mark with the extracting solvent..then follow the above outlined procedure and make triplicate analysis....