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AOAC Official Method 2014.04
Simultaneous Determination of Choline/Carnitine
in Infant Formulas and Adult Nutritional Products
HILIC LC-MS/MS
First Action 2014
A. Principle
Reconstituted test sample is weighed into a microwave reaction vessel. Microwave heating accelerates
an acidic hydrolysis process to release bound choline. A subsequent alkaline degradation is performed to
release L-carnitine from inherent acylcarnitines. Choline and L-carnitine can be determined
quantitatively in nutritional products and raw materials by hydrophilic interaction liquid
chromatography with tandem mass spectrometry (HILIC LC-MS/MS).
B. Apparatus
(
a
)
Column.-
-Acquity UPLC BEH HILIC 1.7
µ
m, 2.1 × 100 mm (Waters Corp., Milford, MA) or equivalent.
(
b
)
Liquid chromatograph.
—Waters Acquity UPLC Binary.
(
c
)
Solvent manager.-
-Capable of 15,000 psi or equivalent (Waters Corp.).
(
d
)
Detector.
—Waters Acquity TQD o r Xevo TQ-S triple quadrupole mass spectrometer (Waters Corp.),
or equivalent.
(
e
)
Injector.
—Waters Acquity sample manager with integrated column oven or equivalent.
(
f
)
Autosampler
.—Waters Acquity with cooler and vials, or equivalent.
(
g
)
Nitrogen generator
.—Peak Scientific (Billerica, MA) Model NM30LA or equivalent.
(
h
)
Data system.
—Waters MassLynx, latest revision or equivalent.
(
i
)
Microwave.
–MarsXpress (CEM, Matthews, NC) or equivalent.
(
j
)
Reaction vessel.-
-50 mL Teflon® (CEM, Matthews, NC, or equivalent).
(
k
)
Centrifuge tubes.
—Polypropylene (PP), 50 mL capacity, disposable, or equivalent.
(
l
)
Vortex mixer with flat and cone top.
(
m
)
Balance 1.—
Readable to at least 0.0001 g (Mettler-Toledo AT200; Columbus, OH, or equivalent).
(
n
)
Balance 2.—
Readable to at least 0.001 mg (Mettler-Toledo XP 6 or equivalent).
(
o
)
Syringe.–
1 mL Luer tip.
(
p
)
Filters.
–0.45 µm nylon membrane with syringe tip or equivalent.
Candidates for 2016 Method of the Year
311