BS ISO 20647:2015 pdf free.Infant formula and adult nutritionals – Determination of total iodine — Inductively coupled plasma mass spectrometry (ICP-MS).
BS ISO 20647 specifies a method for the quantitative determination of total iodine in infant formula and adult nutritional formula.lll The method is applicable to the measurement of total iodine in infant formula and adult nutritional formula from 0,5 pig/bOg to 1 500 pg/bOg reconstituted final product and for ready-to-feed products from 2,5 ig/100 g to 1 000 pg/100 g using ICP-MS.
Using various infant formula and adult nutritional products, the method was subjected to an interlaboratory study. Levels obtained ranged from 3,47 pg/100 g to 124 pig! 100 g. For all precision data related to the interlaboratory study, see Table A.1 located in Annex A.
2 Principle
Digestion occurs using a potassium hydroxide (KOl-l) solution in an oven or open-vessel microwave system. Iodine is stabilized with ammonium hydroxide and sodium thiosulfate after digestion. The solution is brought to volume followed by filtration. The filtrate is analysed directly or after dilution by inductively coupled plasma mass spectrometry (ICP-MS).
3 Reagents and materials
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and distilled or demineralized water or water of equivalent purity. Equivalent chemicals and reagents may be used.
3.1 KOH pellets, certified ACS grade, e.g. Fisher Scientific, Fairlawn, NJ1). NOTE KOH may contribute background levels of iodine.
3.2 Ammonium hydroxide (NH4OH). 28 % to 30 % (rn/rn), certified ACS PLUS, Fisher Scientific1).
3.3 Sodium thiosulfate (Na2S2O3), purity > 99,99 %, metal basis, Fisher Scientific1).
3.4 Surfactant, e.g. Triton®X-100, Sigma, St. Louis, M01).
3.5 Concentrated nitric acid (HNO3), Optima, high purity Fisher Scientific1).
3.6 Perchloric acid (HCIO4), 70 % (rn/rn).
3.7 Purified water, 18 Mfl/cm.
3.8 Reference standards
3.8.1 IodIde standard solution In water, mass concentration p = 1 000 gig/mI, SPEX CertiPrepi).
3.8.2 IodIde standard solution In 1 % triethylamine (TEA). p = 1 000 pg/mI, Inorganic Ventures1).
3.8.3 Standard Reference Material (SRM), National Institute of Standards and Technology (NIST) SRM
1849a, Infant/Adult Nutritional Formula.
Either stock iodide reference solutions may be used for intermediate and working standard solutions preparation. The remaining source may be used as a continuing calibration verification (CCV) standard. Equivalent reference standards may be substituted. ‘Iodide’ may be referred to as ‘iodine’ throughout this International Standard.
3.9 Internal standards
3.9.1 Praseodymium (Pr) standard solution in 5 % HNO3, p = 10 pg/mI. Inorganic Ventures1).
Individual values of iodine are reported for each test sample using praseodymium as the internal standard. Equivalent stock internal standard solutions may be substituted.
3.10 Preparation of reagent solutions
3.10.1 General
Prepare all reagent solutions as recommended by either mass per volume or volume per volume. Adjusting for purity and/or concentration is not required.
3.10.2 KOH solution, p = 50 g/l
Dissolve 25 g of KOH pellets in an appropriate amount of purified water, then dilute to 500 ml with purified water. This solution may be added using a re-pipet volumetric bottle top dispenser. Store this solution at room temperature. Reagent expires 6 months after preparation date.
3.10.3 Stabilizer concentrate
Dissolve 5 g of Na2S2O3 in an appropriate amount of purified water, add 50 ml of NH4OH, then dilute to 500 ml with purified water. The resulting concentration is 10 % NH4OH and 1 % Na2S2O3 in purified water. Store this solution at room temperature. Reagent expires 6 months after preparation date.BS ISO 20647 pdf free download.