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Single Laboratory Validation of CARN-05: Determination of Free and Total
Carnitine and Choline in Infant Formulas and Adult Nutritional Products
Wei Jing, Louis Salvati, and Joseph J. Thompson
Abbott Nutrition, Columbus, OH USA
July 25, 2014
Summary
A single laboratory validation (SLV) has been performed for a method that simultaneously determines
choline and carnitine in nutritional products by LC-MS/MS. All eleven SPIFAN matrices (from the AOAC
Stakeholder Panel on Infant Formulas and Adult Nutritionals) were tested. Depending on the sample
preparation, either the added (free, with a water dilution and filtering) or total (after microwave
digestion at 120° in nitric acid and subsequent neutralization with ammonia) species can be detected.
For non-milk containing products, the total carnitine is almost always equal to the free carnitine. A
substantial difference was noted between free and total choline in all products. All Standard Method
Performance Requirements (SMPRs) for carnitine and choline have been met. This document
summarizes the material sent to the SPIFAN ERP (Expert Review Panel) for the review of this method.
The purpose of performing the SLV is to enlist this method as a candidate for AOAC First Action Status
for carnitine, and also choline as well.
Background
Over the last three years, as part of the SPIFAN program, the AOAC has issued regular Calls For Methods
to find suitable test methods for global dispute resolution purposes for nutritional products. Choline
was considered earlier in the process. SMPR 2012.013 was written and approved in 2012 (in February,
India), describing the performance requirements needed for a choline dispute-resolution method.
Three methods were chosen for consideration from those submitted. Abbott Nutrition submitted
CHOL-06 (OMA #2012.19), an LC-MS/MS method very similar to the present submission. A little later, in
September 2012, SMPR 2012.010 was written and approved for carnitine. Abbott submitted CARN-01
(AOAC 2012.17) in response to the Call For Methods, and this was the only entry for some time.
In 2013, the original Abbott choline method 2012.19 was revamped to meet internal requirements and
to make logical improvements to it. Carnitine was added as an analyte (similar to Nestlé’s publication in
JAOAC 91, 4, 2008) and microwave digestion was added to speed up the typical 3-hour digestion
(similar to NIST publication JAOAC 95, 5, 2012, p. 1479). The combined method was substantially
different than either 2012.19 or 2012.17, and so both methods were withdrawn from the SPIFAN
process. Since the last data was presented to the ERP in March 2014, the method has been put in final
Candidates for 2016 Method of the Year
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