BS EN 1405:2009 pdf free download – Chemicals used for treatment of water intended for human consumption – Sodium alginate.
NOTE Repeatability conditions are conditions where mutually independent test results are obtained with the same method on identical test material in the same laboratory by the same operator using the same equipment within short intervals of time.
5.2.2.3 Ash
5.2.2.3.1 General
This method applies to products with ash in the range 10 % mass fraction to 40 % mass fraction.
5.2.2.3.2 Principle
The organic fraction of the alginate molecule is removed as carbon dioxide and water by heating. The inorganic fraction remains behind as the metal oxide or carbonate, which is weighed as the direct ash. The result is expressed as a percentage by mass calculated with reference to the dried substance (see 5.2.2.2).
5.2.2.3.3 Apparatus
5.2.2.3.3.1 Ordinary laboratory apparatus and glassware together with the following:
5.2.2.3.3.2 Furnace with temperature controller in the range 0 °C to 1 000 °C.
5.2.2.3.3.3 Platinum crucibles with lids, 40 ml capacity.
5.2.2.3.3.4 Platinum tipped tongs.
5.2.2.3.3.5 Desiccator containing silica gel as desiccant.
NOTE The silica gel desiccant should be blue: when pink it requires redrying at 105 °C overnight.
5.2.2.3.4 Procedure
5.2.2.3.4.1 Test portion
Weigh, to the nearest 0,1 mg, 0,5 g of a test sample into a pre-dried, tared platinum crucible (5.2.2.3.3.3).
5.2.2.3.4.2 Determination
Place the lid on the crucible and char the test portion on a hotplate. Place the crucible with charred contents into a furnace (5.2.2.3.3.2) at (650 ± 25) °C and leave for 4 h (or until all the carbon has been burned off, as indicated by the absence of black residue).
Remove the crucible from the furnace and transfer with platinum tipped tongs (5.2.2.3.3.4) to a desiccator (5.2.2.3.3.5) to cool to ambient temperature. Re-weigh the crucible plus contents.
5.2.2.4.4.1 Test portion
Weigh, to the nearest 0,01 g, 5 g of a test sample into a weighing boat.
5.2.2.4.4.2 Determination
Prepare a 1 % mass fraction solution of sodium alginate by dispersing the sample into 495 g of water, whilst stirring with an electric stirrer (5.2.2.4.3.3). Stir for 2 h at approximately 800 min1 (rotational frequency of 13 s1) until the sodium alginate is completely dissolved, and the solution is lump-free. Avoid excessive entrapment of air bubbles.
Calibrate the pH meter (5.2.2.4.3.2) in accordance with the manufacturer’s instructions. Immerse the electrodes in the solution of sodium alginate. Note the pH meter reading once it has stabilised.
5.2.2.4.5 Expression of results
Express the results as pH units, to the nearest 0,1 unit, at 20 °C.
5.2.3 Impurities
Not applicable.
6 Labelling – Transportation – Storage
6.1 Means of delivery
The product shall be delivered in suitable containers, e.g. bulk containers, sacks, drums, cans or bottles. Drums and sacks shall have a moisture barrier, e.g. an internal polyethylene liner.
In order that the purity of the product is not affected, the means of delivery shall not have been used previously for any different product or it shall have been specially cleaned and prepared before use.
6.2 Risk and safety labelling in accordance with the EU Directives.