EN 16169:2012

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.MHOGDKOXSchlamm, behandelter Bioabfall und Boden - Bestimmung des Kjeldahl-StickstoffsBoues, bio-déchets traités et sols - Détermination de l'azote KjeldahlSludge, treated biowaste and soil - Determination of Kjeldahl nitrogen13.080.10Chemical characteristics of soils13.030.20Liquid wastes. SludgeICS:Ta slovenski standard je istoveten z:EN 16169:2012SIST EN 16169:2013en,fr,de01-februar-2013SIST EN 16169:2013SLOVENSKI
STANDARD
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16169
August 2012 ICS 13.030.01; 13.080.10 English Version
Sludge, treated biowaste and soil - Determination of Kjeldahl nitrogen
Boues, bio-déchets traités et sols - Détermination de l'azote Kjeldahl
Schlamm, behandelter Bioabfall und Boden - Bestimmung des Kjeldahl-Stickstoffs This European Standard was approved by CEN on 24 May 2012.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.
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Repeatability and reproducibility data . 10A.1 Materials used in the interlaboratory comparison study . 10A.2 Interlaboratory comparison results . 11Bibliography . 12 SIST EN 16169:2013

WARNING — Persons using this European Standard should be familiar with usual laboratory practice. This European Standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. IMPORTANT — It is absolutely essential that tests conducted according to this European Standard be carried out by suitably trained staff.
Compounds with nitrogen bound in N-N, N-O linkages and some heterocycles (pyridines) are only partially determined. The limit of detection (LOD) is usually 0,03 % nitrogen, and the limit of quantification (LOQ) is 0,1 % nitrogen (using 0,25 mol/l sulfuric acid for titration). 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 15934, Sludge, treated biowaste, soil and waste — Calculation of dry matter fraction after determination of dry residue or water content EN 16179, Sludge, treated biowaste and soil —– Guidance for sample pretreatment EN ISO 3696, Water for analytical laboratory use — Specification and test methods (ISO 3696) EN ISO 5667-15, Water quality — Sampling — Part 15: Guidance on the preservation and handling of sludge and sediment samples (ISO 5667-15) ISO 18512, Soil quality — Guidance on long and short term storage of soil samples 3 Terms and definitions For the purpose of this document, the following terms and definitions apply. 3.1 Kjeldahl nitrogen nitrogen that is contributed by free ammonia, inorganic ammonia compounds and those types of organic nitrogen compounds that are converted to ammonium sulfate by the digestion process described in this standard (catalytic sulfuric acid digestion) [SOURCE: EN 13342:2000, 3.1] 4 Principle The dried and homogenized, moist or liquid material is digested in a suitable Kjeldahl tube with sulfuric acid, thus converting most nitrogen compounds present to ammonium sulfate. To raise the temperature, potassium sulfate is added and e.g. a mixture of titanium dioxide and copper sulfate is used as a catalyst. After adding sodium hydroxide to the digestion solution the produced ammonium is evaporated by distillation as ammonia. This is condensed in the cooling system and flows into a conical flask with boric acid solution (or diluted sulfuric acid). This solution is analyzed for ammonia by titration with sulfuric or hydrochloric acid. SIST EN 16169:2013

Table 2 — Amounts of sulfuric acid consumption by various materials
during Kjeldahl digestion Material Consumption of sulfuric acid (36 mol/l) during digestion ml/g Soil, organic C 10,0 Soil, organic matter 5,8 Al2O3 1,63 Fe2O3 1,04 Clay 0,60 CaCO3 0,55 Silt 0,33 Sand 0 Salicylic acid 6,76 Na2S2O3 0,58 Reduced Fe 1,50
6 Reagents Use only reagents of recognized analytical grade, unless otherwise specified. 6.1 Water, complying with grade 2 according to EN ISO 3696.
6.2 Sulfuric acid, H2SO4, ρ = 1,84 g/ml. 6.3 Catalyst mixture Grind and thoroughly mix 200 g of potassium sulfate (K2SO4), 20 g of copper sulfate pentahydrate (CuSO4 · 5 H2O) and 20 g of titanium dioxide (TiO2), with the crystal structure of anatase, to prepare a mixture: 10:1:1 = K2SO4:CuSO4:TiO2. This catalyst mixture is commercially available. 6.4 Sodium hydroxide, c(NaOH) = 10 mol/l. SIST EN 16169:2013

7 Apparatus Usual laboratory apparatus, and in particular the following: 7.1 Kjeldahl digestion flasks or tubes, suitable for digestion stand (7.2). 7.2 Digestion stand, suitable for digestion of samples with sulfuric acid at a temperature near to 400 °C.
7.3 Distillation apparatus, e.g. of the Parnas-Wagner-type or other suitable distillation apparatus with steam generator. 8 Sample storage and sample pretreatment Store soil samples according to ISO 18512 and sludge samples according to EN ISO 5667-15. For the purpose of this European Standard biowaste may be stored like soil. Pretreat the samples according to EN 16179, if not otherwise specified. Usually, they are dry, homogeneous and of a defined grain size, liquid or moist. Results are referred to dry mass, so that in case of liquid or moist samples a special sample shall be used for the determination of dry mass. Determine the dry mass of the sample according to EN 15934. 9 Procedure 9.1 General Homogeneity of the test sample shall be ensured. 9.2 Digestion Place a test portion of the dried sample, of about 0,2 g to 1 g, or an undried sample with the corresponding dry matter, to the nearest of 0,1 % accuracy in the digestion flask or tube (7.1). Larger test portions are possible; the mass should be chosen according to the nitrogen content. To use the semi-micro or the macro method respective flasks or tubes shall be used with suitable volumes. Add 10 ml sulfuric acid (6.2). NOTE 1 The amount of sulfuric acid may be adapted to the size of the flask or tube. Swirl until the acid is thoroughly mixed with the sample. Allow the mixture to stand and cool. Add 2,5 g of the catalyst mixture (6.3). SIST EN 16169:2013
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