OMB Meeting Book_9-11-14

( i ) Solid-phase extraction (SPE) cartridges.— Silica, 1 g (J.T. Baker P/N 7086-07, www.avantormaterials.com) or equivalent. ( j ) Syringes .—1 mL disposable and 25 mL gas-tight glass with 4 in. stainless steel needles.

AOAC Official Method 2011.18 Myo-Inositol (Free and Bound as Phosphatidylinositol) in Infant Formula and Adult Nutritionals Liquid Chromatography/Pulsed Amperometry with Column Switching First Action 2011

The liquid chromatography method with electrochemical (pulsed amperometry) detection (PAD) allows for the quantitation of myo- inositol in infant, pediatric, and adult nutritional formulas. The concentration of myo-inositol is calculated by comparison with standards of known concentration. Total mM yo-inositol, as defined by AOAC SMPR 2011.007, can be calculated by adding the free myo-inositol and myo-inositol bound as phosphatidylinositol data. The method was validated for the quantitation of free myo- inositol and myo-inositol from phosphatidylinositol only . Repeatability was determined from duplicate triplicate analyses performed on the same day. Intermediate precision was determined from replicate determinations performed over multiple days. Accuracy was determined by spiked recovery experiments (free myo-inositol and myo-inositol from phosphatidylinositol) and by comparison to a reference microbiological assay wi t h and expressed as the percentage of HPLC results relative to microbiological results (free myo-inositol) . Instrument limits of detection and quantitation were determined statistically from injections of low-level standards .and by spiking samples with low levels of free myo-inositol. Caution: Refer to Material Safety Data Sheets (MSDS) of chemicals prior to use and follow safe handling procedures and the suggested personal protective equipment.

A. Apparatus

( a ) Analytical balance .—Minimum weighing capacity of at least 0.0001 g.

( b ) Centrifuge . ( c ) Desiccator .

( d ) N-evap.— With water bath or equivalent . ( e ) Oven .—Capable of maintaining 1 21 0°C. ( f ) pH meter .—With pH 4 and 7 buffers. ( g ) Stir plate .—Multiposition with stir bars. ( h ) Tubing .—PEEK or Teflon 0.007–.01 in. id. ( i ) Vacuum manifold. ( j ) Vortex mixer.

( k ) System HPLC .—Corrosion-resistant autosampler, isocratic pump (2), 6-port switching valve, and pulsed amperometry detector with a gold electrode. Autosampler capable of injecting 20  L. ( l ) Columns .—Dionex CarboPac MA1 (4 × 250 mm) P/N 44066, MA1 (4 × 50 mm) P/N 44067, and PA1 (4 × 50 mm) P/N 43096, or equivalent (www.thermofisher.com/dionex/). B. Materials ( a ) Beakers .—Assorted sizes. ( b ) Centrifuge tubes .—50 mL with Teflon-coated caps. ( c ) Syringe filters .—Nylon, 0.45 and 0.2 μm. ( d ) Filter paper .—Whatman 2V or equivalent (www.whatman. com). ( e ) Erlenmeyer flasks .—50 or 125 mL or equivalent. ( f ) Volumetric flasks .—Assorted sizes.

( g ) Funnels .—Suitable for use with filter paper. ( h ) Pipets .—Volumetric (Class A); assorted sizes.

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