文档介绍：VITAMINS
Vitamin A
b - Carotene
Vitamin A and b - Carotene Determination
b-CAROTENE STANDARD ABSORBANCES AT 440 AND 620 nm
A at 440 nm
and 620 nm
at 440 nm
at 620 nm
A
A
Use absorbances at 440 nm and then convert this to absorbance at 620 nm and subtract from the absorbance at 620 nm to determine the absorbance at 620 due to Vitamin A.
620
Carotenoid Absorbance at 440nm Vitamin A Absorbance at 620 nm
Carotenoid (mg/ml) Vitamin A mg/cuvette (sample)
Absorbance at 440nm
Absorbance at nm
x
x
x
x
x
x
x
x
x
x
x
THIAMIN DETERMINATION
pyrimidine thiazole
Excite thiochrome at 365 nm and measure the absorbance at 435 nm
Thiamin Determination in Foods
 
5 g enriched flour
75 ml N HCl
Make volume to 100 ml
Digest at 1000C for 30 min
Centrifuge and filter
Oxidation of Thiamine
Tube 1 Tube 2
5 ml Sample 5 ml Sample
g NaCl g NaCl
3 ml 6 3 ml NaOH
13 ml Isobutanol 13 ml Isobutanol
Centrifuge Centrifuge
 
Tube 3 Tube 4
5 ml Standard (thiamin) 5 ml Standard (thiamin)
g NaCl g NaCl
3 ml 6 3 ml NaOH
13 ml Isobutanol 13 ml Isobutanol
Centrifuge Centrifuge
 
Thiamin Standard Solution = mg/ml
Calculation of B1 (mg of B1/5 ml assay sample) = (Tube 1 – Tube) / (Tube 3 - Tube 4 )
RIBOFLAVIN DETERMINATION
6,7 Dimethyl-9-D-1-Ribitylisoalloxazine
Fluorometric Method
Autoclave in N HCl for 30 min
Adjust pH to isoelectric point to precipitate proteins
Filter
 Determination: Test Tubes
10 ml sample, + 1 ml of riboflavin standard or 1 ml H2O
+ 1 ml acetic acid, + ml KMnO4 (4%)
+ ml 3% H2O2 -- KMnO4 color should disappear in 10 seconds, + 20 mg powdered Na2S2O4
Calculation
 mg Riboflavin/ml Final Sample Solution