AOAC SPIFAN Nutrients ERP-Final Review (Jan. 2019)

2017.03 (JAN 2019) Amino-02-(ERP Review for Pubs) Tryptophan by enz hyd_Abbott Labs_Method_10172018

FOR ERP USE ONLY DO NOT DISTRIBUTE

HPLC Determination of Total Tryptophan in Infant Formula and Adult/Pediatric Nutritional Formula Following Enzymatic Hydrolysis Jonathan Draher and Norman White Abbott Nutrition, Division of Abbott Laboratories B. Sample Size and Applicability Method is applicable to infant formula and pediatric/adult nutritional products in both powder and liquid forms. Powder samples can be analyzed directly or after reconstitution to ready to fee concentrations. Below are some recommended sample weights and examples: Typical Sample Weights: Target 30 – 50 mg of protein into the sample preparation RTF: 2.0g PWD: ~0.3g but not exceeding 50 mg protein or 2.7g of 25/225 reconstitution with water [0.3g x 225/25 = 2.7g] SRM 1849a : Protein = 13.72 g/100g, or 137.2 mg/g; 0.3g x 137.2 mg/g = 41.16 mg protein into prep. @ 10/100 reconstitution: 2.7 SW : 137.2mg/g x 10/100 x 2.7g = 37.04mg protein If weighing powder direct, add 2 mL water to dissolve the powder.

C. APPARATUS 1. Equipment

a) Analytical balance b) Micro-Analytical Balance

c) Volumetric pipettes: 0.5, 1, 2, 5, 10 mL d) 50 mL polypropylene centrifuge tubes e) Rack capable of holding tubes from d) f) Volumetric flasks, 50 mL, 100 mL, 500 mL, 2000 mL g) pH meter h) Constant temperature oven capable of maintaining 50 (+/- 1) degree Centigrade i) Thermometer (-20 to 110°C), calibrated j) Vortex mixer k) Sonic water bath

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