Assessing analytical variability of measurement of vitamin A in corn-soy blend.
Two multilaboratory investigations were conducted by SUSTAIN to assess variability in the measurement of vitamin A, the marker used to verify levels of vitamin premix addition to enriched/fortified food aid products, including the widely distributed corn-soy blend (CSB). CSB specifications identify AACC Approved Method 86-06 or equivalent methods for vitamin A analysis, however there is no requirement to demonstrate equivalency. CSB samples with known and blinded levels of vitamin A and a reference standard were analyzed by 16 laboratories using their respective methods. Calculated coefficients of variation across all laboratories and methods for unknown samples and reference standard were 35 and 7.1%, respectively, suggesting the largest source of variation is the vitamin extraction procedure. Laboratories generally overestimated low levels and underestimated high levels of vitamin A within the range of 6000 and 16 000 IU/lb. Only two laboratories demonstrated excellent internal precision (+/- 300 IU vitamin A/lb) and reported values within 95% confidence interval for all blinded samples. Results of this study have implications both for quality control in food aid products (due to the use of vitamin A as a marker) and for regulatory oversight of vitamin A content in commercial food products.
Moore
Wayne R
WR
SUSTAIN, 2000 P St, NW, Suite 300, Washington, DC 20036, USA. wmoore56@verizon.net
DeVries
Jonathan
J
MacDonald
John
J
Hare
Lynne
L
Carson
J
J
Chaudhari
P
P
DeVries
J
J
Fontana
J
J
Golz
P
P
King
J
J
MacDonald
J
J
McCullough
C
C
Noggle
S
S
Rasgorshek
E
E
Schorn
S
S
Skogerson
L
L
Sullins
D
D
Sullivan
D
D
Sussman
M
M
Weibel
M
M
D002623:Chemistry Techniques, Analytical; D005504:Food Analysis / Q000379:methods*; D005527:Food, Fortified / Q000032:analysis*; D009753:Nutritive Value; D011786:Quality Control; D012015:Reference Standards; D015203:Reproducibility of Results; D013025:Glycine max / Q000378:metabolism*; D014481:United States; D016885:United States Department of Agriculture; D014801:Vitamin A / Q000032:analysis / Q000737:chemistry*; D003313:Zea mays / Q000378:metabolism*
D014801:Vitamin A