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ournal of
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nternational
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.
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.
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respectively (Table 3). The average results obtained from
the analysis of NIST SRM 1849a were within the certified
ranges or close to the information mass fraction value. Only
an information mass fraction value is given for free choline,
although there is currently nothing provided for total carnitine
from NIST. The average total recoveries (endogenous + added)
shown in Tables 4 and 5 for all matrixes tested from LOQ to
the upper ranges required in the SMPR were 95.9–103.6%.
Analysis of bound sources of carnitine and choline analyzed in
duplicate over 3 days gave average recoveries of 104.6% for
acetylcholine, 96.7% for phosphatidylcholine, and 104.1% for
acetylcarnitine. The level of detection (LOD) was determined
by the mean baseline noise + (3 × SD) from 10 blank replicates,
and then adjusted with the default weights and dilutions used
in the method. An LOD of 0.0034 mg/100 g for both free and
total carnitine analyses and an LOD of 0.0047 mg/100 g for
both free and total choline analyses were achieved. An LOQ
of 0.05 mg/100 g was obtained for both free and total choline
and carnitine. The LOQ was calculated from the lowest working
standard concentration through the default weights and dilutions
used in the method. The analytical range of the method is from
the stated LOQ to 250 mg/100 g choline and 20 mg/100 g
carnitine and is supported by the data collected from the
precision and accuracy experiments. This method meets all
requirements of AOAC SMPRs 2012.010 and 2012.013 for
l
-carnitine and total choline, respectively; the only exception
is an inability to distinguish between
l
- and
d
-carnitine with
this method.
References
(1)
Standard Method Performance Requirements
(2013) J. AOAC Int . 96 , 488,AOAC SMPR
2012.010
. doi: 10.5740/jaoac.int.SMPR2012.010
(2)
Standard Method Performance Requirements
(2013) J. AOAC Int . 96 , 492,AOAC SMPR
2012.013.
doi: 10.5740/jaoac.int.SMPR2012.013
(3) Starkey, D.E., Denison, J. E., Seipelt, C. T., Jacobs, W. A., &
Dowell, D
. (2013) J. AOAC Int . 96 , 1082–1085.doi:10.5740/
jaoacint.13-140
(4) Martin, F., Gimenez, C., Fontannaz, P., Kilinc, T.,
Campos-Giménez, E., & Dowell, D.
(2013) J. AOAC Int . 96 , 1396–1399. doi:10.5740/jaoacint.13-195(5) Oates, K., Chen, L., De Borba, B., Mohindra, D., Rohrer, J., &
Dowell, D
. (2013) J. AOAC Int . 96 , 1400–1406.doi:10.5740/
jaoacint.13-177
(6) Ellingson, D., Pritchard, T., Foy, P., King, K., Mitchell, B.,
Austad, J., Winters, D., Sullivan, D., & Dowell, D
. (2013) J. AOAC Int . 96 , 1068–1072. doi:10.5740/jaoacint.13-128Candidates for 2016 Method of the Year
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