AOAC SPIFAN ERP & Working Group Method Reviews (July 10, 2019)

Table 2011.18C. Interlaboratory study results for myo-inositol

Total No. labs

Total No. replicates

Mean (mg/100 g RTF) SD r

Sample type

SD

RSD r

RSD

HorRat a

R

R

Unbound (free) myo-inositol

Infant formula (NIST SRM 1849a) Infant formula powder soy-based Infant formula powder milk-based Infant formula RTF milk-based

10 10

22 22 16 18 18 22 18 20 20 18 20 18 18 20 20 20 20 18 20 20 16 16 16 20 18 18 18

412 b 4.22 4.23 7.20 3.83 3.11 5.05 5.13 3.17

11.3 11.4 2.75 2.77 0.43 0.127 0.305 3.03 7.26 0.80 0.0660 0.109 1.56 2.57 0.28 0.0455 0.185 0.63 2.57 0.31 0.0368 0.0892 0.96 2.33 0.25 0.0899 0.389 2.92 12.61 1.32 0.0233 0.109 0.46 2.15 0.24 0.0950 0.277 1.85 5.41 0.61 0.0582 0.0910 1.84 2.87 0.30 1.08 2.37 11.3 25.0 2.19 0.150 0.501 6.94 23.2 2.30 0.0261 0.172 3.92 25.9 2.15 0.0301 0.0909 8.36 25.2 1.91 0.0103 0.0576 4.72 26.4 1.86 0.0936 0.358 5.53 21.1 2.02 0.0234 0.0878 6.89 25.8 1.94 0.00 0.00 0.00 0.00 0.00 0.0244 0.0850 7.71 26.9 2.00 11.9 11.9 2.83 2.83 0.44 0.147 0.446 2.32 7.05 0.82 0.0696 0.302 1.41 6.12 0.69 0.0588 0.201 0.78 2.66 0.32 0.0380 0.124 0.94 3.07 0.33 0.152 0.357 3.22 7.55 0.84 0.0280 0.285 0.51 5.23 0.60 0.0990 0.283 1.94 5.56 0.63 0.0659 0.128 1.90 3.70 0.39

8 8 8 8 9 9 8 9 9 8 9 9 9 9 8 9 9 8 7 7 9 8 8 8

Infant formula powder partial hydrolyzed milk-based Infant formula powder partial hydrolyzed soy-based

10

Child formula powder Infant elemental powder

Infant formula RTF milk-based, unfortified

Myo-inositol bound as phosphatidylinositol

Infant formula (NIST SRM 1849a) Infant formula powder soy-based Infant formula powder milk-based Infant formula RTF milk-based

9.26 b 2.10 0.667 0.348 0.214

Infant formula powder partial hydrolyzed milk-based Infant formula powder partial hydrolyzed soy-based

1.64

Child formula powder Infant elemental powder

0.328

0.00

Infant formula RTF milk-based, unfortified

0.305

Unbound (free) myo-inositol plus myo-inositol bound as phosphatidylinositol

Infant formula (NIST SRM 1849a) Infant formula powder soy-based Infant formula powder milk-based Infant formula RTF milk-based

422 b 6.27 4.94 7.53 4.04 4.71 5.42 5.11 3.46

Infant formula powder partial hydrolyzed milk-based Infant formula powder partial hydrolyzed soy-based

Child formula powder Infant elemental powder

Infant formula RTF milk-based, unfortified

a  HorRat = RSD/PRSD ∙ PRSD = 2C –0.15 (C = concentration by mass fraction). b  Results in mg/kg powder.

to 200 mL with laboratory water (0.5 mg/L). Dilute 4 and 1 mL of the 0.5 mg/L myo-inositol working standard to 10 mL with laboratory water (0.2 and 0.05 mg/L). Expiration: 2 weeks. ( d ) Hydrochloric acid, 0.5%.— Add 1.25 mL concentrated hydrochloric acid to approximately 200 mL water in a 250 mL volumetric flask. Dilute to volume with water and mix well. Expiration: 6 months. ( e ) Sodium chloride, 1 N.— Dissolve 5.8 g sodium chloride and dilute to 100 mL with water. Expiration: 1 month. ( f ) Sodium hydroxide, 0.12% or 30 mM (Pump 1).— Quickly weigh 4.8 (±0.1) g of 50% sodium hydroxide into a 2000 mL volumetric flask containing approximately 1900 mL water. ( Note : It is important that the sodium hydroxide does not absorb carbon

dioxide from the air.) Swirl to mix well. Dilute to volume with water and mix well. Expiration: 1 month. ( g ) Sodium hydroxide, 4.0% or 1 M (Pump 2).— Quickly weigh 160 (±3) g of 50% sodium hydroxide into a 2000 mL volumetric flask containing approximately 1900mLwater. ( Note : It is important that the sodium hydroxide does not absorb carbon dioxide from the air.) Swirl to mix well. Dilute to volume with water and mix well. Expiration: 1 month. ( h ) 6% Metaphosphoric acid.— Weigh 6.0 g metaphosphoric acid into a 100 mL volumetric flask. Dissolve and dilute to volume with laboratory water. Mix well. Store refrigerated. Expiration: 1 week. ( i ) Phosphatidylinositol extraction solutions.— Prepare fresh on day of use.

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