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Chem, Res. Center Crete, IL – Report of A Validation of LC-MS/MS Method for Folate Analys
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Table 7: The analysis of folate vitamers in Reference Materials
Reference
Material
Matrix
Folate
Vitamer
Results
Days of
analysis
Reference Value
Mean mcg/g
% RSD
n
mcg/g
NIST 1849a
Infant Formula
Milk Based
Folic Acid
2.28
6.6
50
17
2.293+ 0.062
5-CH3-THF
0.17
12.1
41
14
0.084 + 0.0031
Total Folate*
2.42
5.8
41
14
2.31 (Micro
value)
BCR 485
Dried
Vegetable
Powder
5-CH3-THF
2.62-3.045
9.5
38
18
2.14 + 0.42
Total Folate*
2.71-3.02
12.5
37
13
3.15 + 0.28
NIST 3280
Vitamin Tablet Total Folate*
383.1
1.6
3
1
394 + 22
NIST 1546**
Meat
Total Folate*
Mean ng/g
% RSD
n
3
ng/g
14.3
5.1
15
12*
*Total Folate as Folic Acid; **NIST SRM 1546 Total Folate Value is an Information Value (no uncertainty provided).
Total folate as folic acid obtained by our method for the reference material BCR 485 (dried vegetable
powder) was about 96% of the lowest range specified for this reference material. Recent values of the
analysis using a more sensitive LC-MS/MS gave values with in the BCR specified range. Total folic
acid results obtained by the method for this reference material was well within the BCR specified range
for the analyte (Table 19). 5-methyl-THF in BCR 485 was estimated by the method is either close to
the reported upper range or about 20% higher of this range. Accurate analysis of 5-methyl-THF
analysis requires maintaining its stability during the analysis. In this regards we found that control of
pH of the analyte’s solution is critical particularly after SPE elution and our method incorporates a step
for this purpose.
Folic acid in NIST SRM 3280, a multivitamin and mineral dietary supplement tablet matrix, estimated
by the method matched closely to the NIST specified value. Similarly total folate value as folic acid in
the NIST SRM 1546, meat sample, was found to match with the reference value indicated by the NIST
for this sample.
The closeness of results of the analysis of folate and folate vitamers by the method to the specified
reference values in the reference materials are indicative of the accuracy of the method.
The Precision of the Reference material analysis:
The inter-day precision of the reference material analysis of the method for folate and vitamer analysis
was found to be satisfactory and in terms of % RSD ranged between 1.6 to 12.5%.
The analysis of various reference materials over a period of about 3 months also provided a satisfactory
accuracy and precision of the method. The Folic acid results obtained for the NIST SRM 1849a by the
method over a period of about 3 months are presented in Table 8.
The accuracy and intraday precision (% RSD range = 0.4-7.8%) as well as inter-day precision (% RSD
= 6.6%) of the method over a period of about 3 months was found to be satisfactory.
2011.06/Fol-22 (February 2016)
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