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: 5 of 11
c.
Repeat the reading a further two times, rinsing the sample cuvette with the solution
before each reading. Calculate the average absorbance reading.
d.
The potency of the vitamin A Acetate stock solution is then calculated as follows:
Where:
ABS = average absorbance reading, determined above; 1560 = extinction coefficient of
retinyl acetate at 325nm; 10000 = conversion of percentage to µg/mL.
dl-α-Tocopherol Acetate
a.
Pipette 3mL of stock solution E1 into a 100mL volumetric flask and make up to volume
with
ethanol
.
b.
Determine the absorption at 284 nm, zeroed against ethanol in a 1cm quartz cell.
c.
Repeat the reading a further two times, rinsing the sample cuvette with the solution
before each reading. Calculate the average absorbance reading.
d.
The potency of the dl-α-tocopherol acetate stock solution is then calculated as follows:
DL-α-tocopherol acetate (mg/mL) =
ABS × 100 × 10
43.6
3
Where:
ABS = average absorbance reading, determined above; 43.6 = extinction coefficient of
tocopheryl acetate at 284 nm; 10 = conversion of percentage to mg/mL.
DL-α-Tocopherol
a.
Pipette 3mL of stock solution E2 into a 100mL volumetric flask and make up to volume
with
ethanol.
b.
Determine the absorption at 292 nm, zeroed against ethanol in a 1cm quartz cell.
c.
Repeat the reading a further two times, rinsing the sample cuvette with the solution
before each reading. Calculate the average absorbance reading.
d.
The potency of the DL-α-tocopherol stock solution is then calculated as follows:
Vitamin A Acetate (µg/mL) = ABS × 100 × 100 × 10000
1560
3
3
Vitamin A & E - MLT
For ERP Use Only
DO NOT DISTRIBUTE
Page 5
