BS EN 15934-2012 pdf download.Sludge, treated biowaste, soil and waste Calculation of dry matter fraction after determination of dry residue or water content.
NOTE 2 The material ol the evaporatmg dish or crucible should be compatible with the nature of the sample to avoid interferences upon weighing due to possible oxidations.
6.5 Procedure
Place an evaporating dish or crucible (6.4.4) in the drying system (6.4.1) set at (105 i 5) C for a minimum of 30 mm, After cooling in the desiccator (6.4.2) to ambient temperature, weigh the basin to the nearest 1 mg.
Depending on the expected dry residue, weigh into the evaporating dish or crucIble (6.4.4) a suitable amount of material so that the residue obtained has a weight of at least 0.5 g. Weigh the loaded basin to the nearest 1 mg.
Place the evaporating dish or crucible (6.4.4) containing the sample in the drying system (6.4.1) set at (105 ± 5) C until the residue appears dry, typically overnight.
NOTE For some samples e.g. sludge, there is a risk of formatkn of a cake surface, which hinders an even drying, To avoid this, a glass rod can be weighed along with the dish. If cake formation occurs during drying, the glass rod is used to stir the sample, to break up the cake. This should be repeated as necessary. The rod should be reweighed afterwards.
After cooling in the desiccator (6.4.2) weigh the evaporating dish or crucible and contents for the first time.
The dry residue shall be regarded as constant if the mass obtained after further 1 h of drying does not differ by more than 0,5 % of the previous value or 2 mg whichever is the greater. Otherwise repeat the drying process. In case of weight inconstancy after three cycles the drying process may be stopped (after at least 16 h). The result of the last weighing shall be recorded in the test report. A drying period of 16 h is sufficient.
In case of infrared or halogen lamp drying systems the corresponding manufacturer’s instructions apply. The technique of choice shall be recorded in the test report.
Other techniques than oven drying, infrared or halogen lamp drying are allowed, provided they are proven to give comparable results.
6.6 Calculation of results
The dry residue is calculated according to Formula (1):
7.1 Interferences
Substances like peroxides. oxides, hydroxides. ammonia, carbonates, hydrogen carbonates. disulfites, nitrite, sulfite. thiosulfate, hydrazine and derivatives, iron (II), copper (I). tin (II). silanoles, arsenite, arsenate, selenite, tellurite, phenols, boric compounds, aldehydes, acetone and other reactive ketones may cause interferences. Especially all reductive or oxidative reagents are potentially interferIng. In case of concern about interferences results can be verified by azeotropic distillation (Annex B).
Most of the interferences are reduced in case of extraction with methanol before analysis.
7.2 Reagents
All reagents used shall be at least of analytical grade and suitable for their specific purposes, Hygroscopic substances shall be stored in a desiccator.
7.2.1 Karl-Fischer reagent as recommended by provider of KF-system.
7.2.2 Methanol. The methanol used shall not contain more than a mass fraction of 0005 % water.
7.2.3 Toluene if necessary to solve a sample.
7.3 Apparatus
Usual laboratory glassware and the foDowing equipment shall be used.
7.3.1 Karl-Flscher-titrator.
7.3.2 Shaking device.
7.3.3 Weighing pipette.
7.3.4 Conical flasks, 250 ml with ground glass neck and stopper.
7.4 Procedure
7.4.1 Determination of the equivalence factor
Fill the titration vessel (7.3.1) with methanol (7.2.2). Stir without splattering. Titrate with Karl-Fischer reagent (7.2.1) to the end point. Using a weighing pipette (7.3.3) add approximately 80 mg of water (I) with an accuracy of 0,1 %. Titrate to the end point and record the consumption (Vi).
The equivalence factor F is calculated according to Formula (2):
9 Precision
The performance characteristics of the methods have been evaluated (see Annex A).
10 Test report
The test report shall contain at least the following information:
a) a reference to this European Standard (EN 15934):
b) complete identification of the sample;
C) the applied method (Method A or Method B)
d) expression of results. accocding to Clause 8:
e) any details not specified in this European Standard or which are optional, as well as any factor which may have affected the results.BS EN 15934-2012 pdf download.