BS 17265:2019 pdf download – Foodstuffs – Determination of elements and their chemical species – Determination of aluminium by inductively coupled plasma optical emission spectometry (ICP-OES)

BS 17265:2019 pdf download – Foodstuffs – Determination of elements and their chemical species – Determination of aluminium by inductively coupled plasma optical emission spectometry (ICP-OES) 6.2 Digestion vessels, e.g. of polyfluoropolymers or quartz with volumes from 70 ml to 100 ml. 6.3 Test tube shaker, optional. 6.4 Analytical balance, capable to weigh to the nearest milligram. 7 Procedure 7.1 Digestion 7.1.1 General To ensure complete dissolution of aluminium the following shall be respected: — ensure that the sample is sufficiently homogeneous; — in case of incomplete digestion or high aluminium contents, it may be beneficial to use a test portion as small as possible (at least 200 mg for dry samples) in order to digest aluminium compounds as completely as possible; — for samples containing silicates, digestion temperatures above 220 °C may be necessary in order to dissolve the aluminium as completely as possible; — in case of samples with low water content, first add water and mix intensively, before adding concentrated nitric acid; — do not use hydrogen peroxide for digestion. Further instructions regarding test portions and digestion are given in B.2 and B.3. For pressure digestion according to EN 13805, different vessels may be used depending on the instrument type and manufacturer. The maximum test portion and the minimum liquid volume depend on the pressure stability of the respective vessels. The specifications according to 7.1.2 refer to digestion vessels with volumes from 70 ml to 100 ml and a minimum liquid volume of 5 ml. All indications in 7.1.2 shall be adjusted to the digestion instrument used. For safety reasons the manufacturer’s specifications shall be strictly followed. 7.1.2 Digestion procedure Before digestion, different amounts of water, depending on the different types of food [3], are added in order to obtain comparable acid concentrations in the final digestion solution. The amount of water to be added depends on the test portion and thus on the content of carbon and water in the food type. Add just as much water to the test portion that is necessary to suspend the food completely. Then complete the test portion with water to reach 3 g. Water is also added to fat-containing foods, even if a suspension is hardly possible. Example for digestion of powdery food: Add 2,5 ml of water to the dry food, e.g. 0,5 g of flour. Mix the contents of the digestion vessel intensively, e.g. on a test-tube...