Determination of Myo-Inositol - AOAC International
Determination of Myo-Inositol - AOAC International
Determination of Myo-Inositol - AOAC International
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4 Schimpf et al.: Journal <strong>of</strong> aoac international Vol. 95, no. 4, 2012<br />
Table 1. Free myo-inositol validation data—<br />
intermediate precision, mg/100 g<br />
HPLC method<br />
Day<br />
Product type 1 2 3<br />
Hypoallergenic infant formula RTF 8.11 8.06 8.17<br />
n 3 3 3<br />
RSD, % 3.64 5.01 3.40<br />
Soy-based infant formula powder 31.1 31.8 30.9<br />
n 3 3 3<br />
RSD, % 2.49 0.327 1.35<br />
Specialty infant formula RTF 19.7 18.9 19.0<br />
n 3 3 3<br />
RSD, % 1.60 0.976 1.73<br />
Milk-based infant formula RTF 4.36 4.43 4.38<br />
n 3 3 3<br />
RSD, % 1.91 4.26 0.784<br />
Very low-fat infant formula powder 125 126 122<br />
n 3 3 3<br />
RSD, % 1.46 3.37 1.19<br />
Free amino acid-based infant formula<br />
powder<br />
65.5 65.0 64.9<br />
n 3 3 3<br />
RSD, % 1.56 1.20 2.78<br />
Pediatric nutritional beverage 10.3 10.5 11.1<br />
n 3 3 3<br />
RSD, % 2.02 1.00 4.19<br />
Adult nutritional beverage 91.6 92.3 NA a<br />
n 4 4<br />
RSD, % 1.35 1.22<br />
a NA = No data generated.<br />
Table 3. Free myo-inositol validation data—accuracy data<br />
Product type<br />
HPLC method a ,<br />
mg/100 g<br />
Table 2. Free myo-inositol validation data—<br />
intermediate precision, mg/100 g<br />
Product type n Avg.<br />
Hypoallergenic infant formula RTF 9 a<br />
Soy-based infant formula powder 9 a<br />
Specialty infant formula RTF 9 a<br />
Milk-based infant formula RTF 20 b<br />
Very low-fat infant formula powder 9 a<br />
Free amino acid-based infant formula powder 9 a<br />
Pediatric nutritional beverage 9 a<br />
Adult nutritional beverage 8 c<br />
a Intralaboratory triplicate analyses on 3 days.<br />
HPLC method<br />
RSD,<br />
%<br />
8.13 3.58<br />
31.3 1.89<br />
19.2 2.22<br />
4.39 2.53<br />
125.0 2.72<br />
65.0 1.82<br />
10 4.25<br />
91.9 1.25<br />
b Intralaboratory single, duplicate, or triplicate analyses on 9 days.<br />
c Intralaboratory quadruplicate analyses on 2 days.<br />
Thoroughly mix or stir products prior to sampling. For<br />
liquid products, accurately weigh 0.5 to 5 g (±10%) <strong>of</strong> product<br />
into a 100 mL volumetric flask and record the weight to the<br />
nearest 0.0001 g. For powdered products that do not require<br />
reconstitution, accurately weigh 0.25 to 1.5 g powder into a<br />
100 mL volumetric flask and record the weight to the nearest<br />
0.0001 g. Add approximately 10 to 15 mL laboratory water<br />
to the volumetric and swirl or stir to completely dissolve the<br />
powder. For powdered products that are not homogeneous at<br />
the subgram level, reconstitute following the product label<br />
instructions and accurately weigh 0.5 to 5 g reconstituted product<br />
into a 100 mL volumetric flask. Record the weight to the nearest<br />
0.0001 g. Add enough 0.5% hydrochloric acid to each sample<br />
to adjust the sample pH to 4.5 ± 0.2 and swirl to mix. Allow the<br />
volumetric flasks to set a minimum <strong>of</strong> 2 min. Dilute to volume<br />
with laboratory water and mix well. Filter samples through<br />
Whatman 2V filter paper into 125 mL Erlenmeyer flasks. (Note:<br />
Although some samples will filter cloudy, the filtrates can still<br />
be used.) Filter an aliquot <strong>of</strong> sample filtrate through a 0.45 µm<br />
syringe filter into an autosampler vial.<br />
(b) Sample preparation for phosphatidylinositol<br />
determinations.—(1) Extraction.—Weigh 4 g (±10%) liquid<br />
Microbiological method b ,<br />
mg/100 g HPLC/micro, %<br />
Hypoallergenic infant formula RTF 8.13 7.4 110<br />
Soy-based infant formula powder 31.3 37.0 84.5<br />
Specialty infant formula RTF 19.2 19.0 101<br />
Milk-based infant formula RTF 4.39 3.7 119<br />
Very low-fat infant formula powder 125.0 140.0 89.2<br />
Free amino acid-based infant formula powder 65.0 62.0 105<br />
Pediatric nutritional beverage 10.6 11.0 96.6<br />
Adult nutritional beverage 91.9 83.0 111<br />
a Multiple intralaboratory analyses on multiple days.<br />
b Single analyses.