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

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

Table 5. The method precision for folic acid analysis in the SPIFAN folate MLT samples

Total No. of labs

Total No. of replicates

Overall mean of all data (grand mean)

RSD r

RSD R

HorRat

Sample No.

MLT samples

Sum [ n (L)]

μg/100 g

% % HorRat

P

1 2 3 4 5 6 7 8 9

Milk-based infant formula

11

22 20 22 33 30 22 22 22 22 22 22

137.8 128.6 153.9 211.1 153.5 313.9

5.9 9.8

0.64

10 a

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

4.1 12.5 0.81 6.6 15.1 1.01 6.8 11.1 0.78

11 11

10 b

Soy-based infant formula

6.7 9.5

0.63

Low-Fat adult nutritional powder

11 11 11 11 11 11

4.8 10.0 0.74 3.9 11.1 0.62 5.1 17.3 0.81 4.2 10.2 0.75 5.4 12.1 0.87 3.2 10.6 0.61 ≤11% ≤32% 0.5–2.0 ≤7% ≤16% 0.5–2.0

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

48.5 14.4

314.7 257.9

10 11

Infant elemental powder

Adult nutritional RTF high-fat liquid

56.8

Specifications Specifications

0.5–21.5

AOAC SMPR 2011.006 Requirements/Satisfactory Performance

>21.5

a  Data from laboratory 7 removed (Cochran’s test). b  Data from laboratory 8 removed (Cochran’s Test).

Table 6. The method precision for 5-CH3-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

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

17.5 2.77 <0.5 32.6 <0.5

11.0 11.8

24.8 30.0

1.19 1.09

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

— a

— —

10.6

11.2

0.59

Soy-based infant formula

— — —

Low-fat adult nutritional powder

1.0

12.2

31.0

0.97

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

<0.5

— — —

1.2

18.4

20.8 16.0

0.67 0.85

33.3 <0.5 <0.5

8.9

10 11

Infant elemental powder

— — — — — —

Adult nutritional RTF high-fat liquid

a  — = Not applicable.

of 17.3%. HorRat in all cases was in the range of 0.61 to 1.0 (Table 5). The 5-CH3-THF concentration in the liquid RTF samples ranged from <0.5 to 1.2 μg/100 g, and in the powder samples, it ranged from <0.5 to 33.3 μg/100 g. The 5-CH3-THF RSD r was in the range of 8.9 to 10.6%, and RSD R was in the range of 11.2 to 16.0% for samples with a concentration >21.5 μg/100 g. The samples with 5-CH3-THF concentration less than 21.5 μg/100 g had RSD r in the range of 11.0 to 18.4% and RSD R of 20.8 to 31.0%. HorRat, in all cases in which 5-CH3-THF could be quantitated, was in the range of 0.67 to 1.19 (Table 6). The 5-CHO-THF concentration in all the liquid RTF samples was <0.5 μg/100 g, and in the powder samples, it ranged from <0.5 to 20.8 μg/100 g. Soy-based infant formula samples had the highest concentration (20.5 and 20.8 μg/100 g) among the

MLT sample analyzed. The low-fat adult nutritional sample provided a value of 9.2 μg/100g. The 5-CHO-THF RSD r was in the range of 7.9 to 14.0%, and RSD R was in the range of 26.1 to 32.2%. HorRat, in all cases in which 5-CHO-THF could be quantitated, was in the range of 1.1 to 1.5 (Table 7). Folic acid repeatability and reproducibility precisions were found to be within the limit specified for total folate in the SMPR (18), and HorRat values were found to be satis­ factory. 5-CH3-THF and 5-CHO-THF at concentration levels <21.5 μg/100 g provided RSD r in a range of 8 to 18%, the later is somewhat higher than suggested by SMPR for total folate. Concentration of relevant folate vitamers in samples exhibiting a relatively higher RSDr values was <3.5 μg/100 g. The RSD R , however, was within the SMPR’s specifications for total folate and within in the range of 21 to 32%. 5-CH3-THF in two of