AOAC SPIFAN Nutrients ERP-Final Review (Oct. 2018)

B handari et al . : J ournal of AOAC I nternational V ol . 101, N o . x , 2018  13

Table 7. The method precision for 5-CHO-THF analysis in the SPIFAN folate MLT samples

Total No. of labs

Total No. of replicates

Grand mean

RSD r

RSD R

HorRat

Sample No.

MLT samples

μg/100 g

% % HorRat R

P

n

— a

1 2 3 4 5 6 7 8 9

Milk-based infant formula

11 11 11 11 11 11 11 11 11 11 11

22 22 22 33 33 22 22 22 22 22 22

<0.5 <0.5 20.8

— —

Infant formula powder, partially hydrolyzed milk-based Infant formula powder, partially hydrolyzed soy-based NIST SRM 1869 Infant/Adult Nutritional Formula

— — —

11.1 13.7

29.4 28.4 26.1 32.2

1.5 1.1 1.3 1.4

3.3

Soy-based infant formula

20.5

9.1 7.9

Low-Fat adult nutritional powder

9.2

Adult nutritional RTF high-protein liquid Infant formula RTF milk-based liquid Child formula powder, milk-based

<0.5 <0.5

— — — — — —

3.0

14.0

29.5

1.1

10 11

Infant elemental powder

<0.5 <0.5

— — — — — —

Adult nutritional RTF high-fat liquid

a  — = Not applicable.

Table 8. Folate vitamers as percent of total folate as folic acid in the SPIFAN MLT samples a

Sample No.

MLT samples

Folic acid

5-CH3-THF

5-CHO-THF

1 2 3 4 5 6 7 8 9

Milk-based infant formula

89.0 97.8 88.7 85.9 88.8 97.1 99.0 91.6 90.0 99.8 99.5

11.2

Infant formula powder, partially hydrolyzed milk-based Infant formula powder, partially hydrolyzed soy-based NIST SRM 1869 (Infant/ Adult Nutritional Formula)

2.1

11.9

13.4

1.4

Soy-based infant formula

11.8

Low-fat adult nutritional powder

0.3

2.8

Adult nutritional RTF high-protein liquid Infant formula RTF milk-based liquid Child formula powder, milk-based

8.0 9.6

0.8

10 11

Infant elemental powder

Adult nutritional RTF high-fat liquid

the analyzed samples was >21.5 μg/100 g and had RSD r in the range of 9 to 11%, which was somewhat higher than expected by the SMPR for total folate. The RSD R was in the range of 11 to 16% and within the limits suggested by the SMPR for total folate (18). HorRat, in all cases in which 5-CH3-THF and 5-CHO-THF could be quantitated, were in the satisfactory range (0.59–1.5). The distribution of the folate vitamers as percent of total folate (as folic acid) in the samples is provided in Table 8. As expected, folic acid accounts for most of the total folate contents (86–100%) in all of the samples. 5-CH3-THF was found to account for 8 to 13% of total folate in four of the 11 samples studied. It could not be quantitated or accounted for 2% or less of total folate in all of the other samples. 5-CHO- THF was found to account for a significant amount (i.e., about 12% of total folate) in only two samples, both of which were soy-based. It could not be quantitated or accounted for 3% or less of total folate in all of the other samples. The method has demonstrated its compliance with the applicability as required by the folate SMPR 2011.006 (18) and has shown to be suitable for the analysis of folate in a wide range of infant formulas and adult nutritionals. The method

performance with respect RSD r was found to be satisfactory. These results were submitted to SPIFAN in September 2017. Based on the aforementioned data, the method was recommended to advance forward to Final Action status. The participants in the MLT study were invited to make comments on the method performance in their laboratory. In general, comments were positive with respect to the capability of the method. Other comments were minor and were seeking additional clarification in specific steps of the method, which were provided to the study participants and, if relevant, were added to the updated method. Safety concerns of the method were evaluated, and there were no major hazards recognized beyond those typically found in modern chemistry laboratories. The method users are directed to use appropriate safety equipment when handling acids, bases, and solvents, and to refer to the Material Safety Data Sheets for detailed safety instructions for each chemical’s use and disposal. The waste generated by the method should be disposed off according to the relevant local and national guidelines. The described method is accurate, precise, and reproducible for the analysis of total folate in infant formula and adult nutritionals. as well as RSD R