Lab - Ascorbic Acid Analysis Flashcards Preview

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Flashcards in Lab - Ascorbic Acid Analysis Deck (12)
1

T or F
Ascorbic acid is extremely labile on exposure to heat and air, except in alkaline media.

F
acid dapat

2

Chemical methods for the determination of Vitamin C are based on ___ of the vitamin
A. reducing properties
B. polarity
C. both A and B
D. neither A nor B

A

3

titration method of determination: iodine + acid extract, with ___(indicator) in the presence of light/an oxidizing agent
A. phenolphthalein
B. bromcresol green
C. methylene blue
D. all of the above

C

4

Which is not part of the fluorometric method of determining VitC?
A. reduction to dehydroascrobic acid
B. reaction to 0-phenylendamine
C. both are part
D. both are not part

A

oxidation dapat

5

What method + specific modification of it does the FNRI employ for Ascorbic Acid determination?

Bolin and Book modification of Roe and Oesterling colorimetric method

6

What method was used for the experiment?

Roe and Kuether method

7

Which acids function to reduce the pH of the extracting medium?
A. Acetic and trichloroacetic
B. Trichloroacetic and oxalic
C. Acetic and oxalic
D. Oxalic and metaphosphoric

D

8

By shaking with __, the ascorbic acid is oxidized to dehydroascorbic acid

"Norite"

9

Function of thiourea

Stabilize Vitamin C

10

After coupling with ___, the solution is treated with H2SO4 to produce a red color, to be measured photometrically

2,4 dinitrophenylhydrazine

11

In the standard curve, identify the ordinate

Optical density values

12

In the standard curve, identify the abscissa

Concentration of ascorbic acid