SIMULTANEOUS DETERMINATION OF 13-CIS AND ALL-TRANS VITAMIN A PALMITATE (RETINYL
PALMITATE), VITAMIN A ACETATE (RETINYL ACETATE), AND TOTAL VITAMIN E (Α-TOCOPHEROL
AND DL-Α-TOCOPHEROL ACETATE) IN INFANT FORMULA AND ADULT NUTRITIONALS BY
NORMAL PHASE HPLC
CODE:
DATE:
PAGE:
VER:
Purpose:
AOAC 2012.10
Jan 2014
1 of 11
04
AOAC MLT Study
Page: 6 of 11
DL-α-tocopherol (mg/mL) = ABS × 100 × 10
75.8
3
Where:
ABS = average absorbance reading, determined above; 75.8 = extinction coefficient of
tocopherol at 292 nm; 10 = conversion of percentage to mg/mL.
Calculation of working standard concentrations
The concentration of each vitamin in the working standards is calculated from the stock
concentration using the appropriate dilution factor as show below.
Vitamin A Palmitate (µg/mL)
=
Stock (µg/mL)
× 4
×
4
×
X
50
50
50
Vitamin A Acetate (µg/mL)
=
Stock (µg/mL)
×
4
×
4
×
X
50
50
50
Vitamin E Alcohol (mg/mL)
=
Stock (mg/mL)
× 20 ×
4
×
X
50
50
50
Where as X = 0.5mL, 2mL, 4mL, 8mL, 16mL and 32mL respectively for the calibration
levels
L. SAMPLE PREPARATION
a.
Transfer 25g (W1), accurately weighed to a 250mL schott bottle. Dissolve using warm
water (about 40 to 45
0
C), cool, and make up to 200g (W2) with water. Transfer 5.0g
(W3) of reconstituted sample to a screw-top centrifuge tube.
Samples weight (powder equivalent) g = (W1 x W3) / W2
Vitamin E Acetate (mg/mL)
=
Stock (mg/mL)
× 7 × 4 ×
X
50
50
50
Vitamin A & E - MLT
For ERP Use Only
DO NOT DISTRIBUTE
Page 6
