Determination of total organic carbon in limestone

This European Standard specifies methods for the determination of the total organic carbon content (TOC) in limestone.
The standard describes the reference method and alternative methods which can be considered to be equivalent.
In the case of a dispute, only the reference method is used.
Any other methods may be used provided they are calibrated, either against the reference method or against internationally accepted reference materials, in order to demonstrate their equivalence.

Bestimmung des Gesamtgehalts an organischem Kohlenstoff in Kalkstein

Diese Europäische Norm legt Verfahren für die Bestimmung des Gesamtgehalts an organischem Kohlenstoff (TOC, en: total organic carbon) in Kalkstein fest.
ANMERKUNG   Dieses Verfahren behandelt die Bestimmung von TOC < 1 %.
Diese Norm beschreibt das Referenzverfahren und Alternativverfahren, die als gleichwertig betrachtet werden können.

Determination du carbone organique total dans le calcaire

La présente Norme européenne spécifie les méthodes de détermination de la teneur en carbone organique total (COT) du calcaire.
NOTE Cette méthode couvre la détermination de la COT < 1 %.
La norme décrit la méthode de référence et les variantes qui peuvent être considérées comme équivalentes.

Določevanje celotnega organskega ogljika v apnencu

Ta evropski standard določa metode za določevanje celotnega organskega ogljika (TOC) v apnencu.
V tem standardu so opisane referenčna metoda in alternativne metode, ki se lahko obravnavajo kot enakovredne.
V primeru spora se uporabi le referenčna metoda.
Uporabijo se lahko tudi druge metode, če so umerjene glede na referenčno metodo ali mednarodno sprejete referenčne materiale, s čimer se dokaže njihova enakovrednost.

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Bestimmung des Gesamtgehalts an organishchem Kohlenstoff in KalksteinDetermination du carbone organique total dans le calcaireDetermination of total organic carbon in limestone91.100.10Cement. Mavec. Apno. MaltaCement. Gypsum. Lime. MortarICS:Ta slovenski standard je istoveten z:EN 13639:2017SIST EN 13639:2017en01-december-2017SIST EN 13639:2017SLOVENSKI

STANDARDSIST EN 13639:2004/AC:2004SIST EN 13639:20041DGRPHãþD
SIST EN 13639:2017
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 13639
September
t r s y ICS
{ sä s r rä s r Supersedes EN
s u x u {ã t r r tEnglish Version

Determination of total organic carbon in limestone Determination du carbone organique total dans le calcaire

Bestimmung des Gesamtgehalts an organischem Kohlenstoff in Kalkstein This European Standard was approved by CEN on

t x June
t r s yä

egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä

translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä

CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Serbiaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey and United Kingdomä

EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels

t r s y CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN

s u x u {ã t r s y ESIST EN 13639:2017
EN 13639:2017 (E) 2 Contents Page

European foreword ....................................................................................................................................................... 4 1 Scope .................................................................................................................................................................... 5 2 Normative references .................................................................................................................................... 5 3 General requirements for testing .............................................................................................................. 5 3.1 Number of tests ................................................................................................................................................ 5 3.2 General statistical terms .............................................................................................................................. 5 3.3 Expression of masses and results .............................................................................................................. 6 3.4 Blank determinations .................................................................................................................................... 6 3.5 Sampling and sampling preparation ........................................................................................................ 6 3.6 General test principles .................................................................................................................................. 6 4 Reagents ............................................................................................................................................................. 7 5 General apparatus .......................................................................................................................................... 9 5.1 Balances .............................................................................................................................................................. 9 5.2 Laboratory ovens ............................................................................................................................................ 9 5.3 Crucibles .......................................................................................................................................................... 10 6 Gravimetric method with wet oxidation (reference method) ..................................................... 10 6.1 Principle .......................................................................................................................................................... 10 6.2 Apparatus ........................................................................................................................................................ 10 6.3 Procedure........................................................................................................................................................ 11 6.4 Calculation ...................................................................................................................................................... 12 7 Gravimetric method with furnace oxidation (alternative method No. 1) ............................... 12 7.1 Principle .......................................................................................................................................................... 12 7.2 Apparatus ........................................................................................................................................................ 12 7.3 Procedure........................................................................................................................................................ 14 7.4 Calculation ...................................................................................................................................................... 14 8 Infrared detection method with furnace oxidation (low temperature) (alternative method No. 2) ................................................................................................................................................ 15 8.1 Principle .......................................................................................................................................................... 15 8.2 Apparatus ........................................................................................................................................................ 15 8.3 Procedure........................................................................................................................................................ 17 8.4 Calculation ...................................................................................................................................................... 18 9 Infrared detection or conductivity methods with furnace oxidation (high temperature): procedure A (alternative method No. 3) ................................................................ 19 9.1 Principle .......................................................................................................................................................... 19 9.2 Apparatus ........................................................................................................................................................ 19 9.3 Procedure........................................................................................................................................................ 20 10 Infrared detection or conductivity methods with furnace oxidation (high temperature): procedure B (alternative method No. 4) ................................................................ 21 10.1 Principle .......................................................................................................................................................... 21 10.2 Apparatus ........................................................................................................................................................ 21 10.3 Procedure........................................................................................................................................................ 21 SIST EN 13639:2017

EN 13639:2017 (E) 3 11 Repeatability and reproducibility standard deviation, determination limit ......................... 22 12 Test report ...................................................................................................................................................... 22 Annex A (informative)

Features of commercial HF (High Frequency) combustion/infrared carbon analyzers ........................................................................................................................................... 23 A.1 Combustion ..................................................................................................................................................... 23 A.2 Infrared gas analyser .................................................................................................................................. 24 Annex B (informative)

Assignment of reagents to methods ...................................................................... 25 Bibliography ................................................................................................................................................................. 27

SIST EN 13639:2017

EN 13639:2017 (E) 4 European foreword This document (EN 13639:2017) has been prepared by Technical Committee CEN/TC 51 “Cement and building limes”, the secretariat of which is held by NBN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 2018, and conflicting national standards shall be withdrawn at the latest by March 2018. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 13639:2002. In comparison to EN 13639:2002, the following change has been made: In Clause 10 a new alternative method, Alternative method No. 4, developed in Sweden, has been included. According to the CEN-CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 13639:2017

EN 13639:2017 (E) 5 1 Scope This European Standard specifies methods for the determination of the total organic carbon content (TOC) in limestone. NOTE This method covers the determination of TOC in < 1 %. The standard describes the reference method and alternative methods that can be considered to be equivalent. 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. ISO 3310-1, Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth ISO 11464, Soil quality — Pretreatment of samples for physico-chemical analysis 3 General requirements for testing 3.1 Number of tests Where the analysis is one of the series subject to statistical control, determination of the total organic carbon content by a single test shall be the minimum required. Where the analysis is not part of a series subject to statistical control, the number of tests for determination of the total organic carbon content shall be two (see also 3.3). In case of dispute, only the reference method is used. In case of dispute, the number of tests for determination of the total organic carbon content shall be two (see also 3.3). Any other method may be used provided it is calibrated, either against the reference method or against internationally accepted reference materials, in order to demonstrate its equivalence. 3.2 General statistical terms Repeatability standard deviation - the standard deviation of test results obtained under repeatability conditions where independent test results are obtained with the same method on identical material tested in the same laboratory by the same operator using the same equipment within short intervals of time. Reproducibility standard deviation - the standard deviation of test results obtained under reproducibility conditions where test results are obtained with the same method on identical material tested in different laboratories with different operators using different equipment. NOTE Definitions are based on ISO 3534-1 [1]. The standard deviations of repeatability and reproducibility are expressed in absolute percent. Determination limit (Formula (1)) - is the content where its relative uncertainty, which is assigned to a fixed probability level, and defined as the quotient of the half of a two-side prognosis interval and the content to be assigned to the determination limit, is equal to a pre-set value. SIST EN 13639:2017

EN 13639:2017 (E) 6 2.()11DlDlxDfxxxxkstnpQα−=××++ (1) where:

is the probability level f is the variability (number of degrees of freedom) DlDlxxk∆=1 is the relative uncertainty ∑=−=niixxxQ12)( is the number of calibration samples n number of test results p is the number of analyses of each calibration sample sxD is the standard deviation of the procedure t is the quantile of the t-distribution (f = n

xi is the analysed content assigned to a calibration sample x is the arithmetic mean of the contents assigned to all calibration samples xDl is the determination limit

¿xDl is half width of the two-side prognosis interval

NOTE This determination limit is based on DIN 32645 [2]. 3.3 Expression of masses and results Express masses in grams to an accuracy of ± 0,000 5 g. Express the results as a percentage to at least two decimal places, if the difference between the individual test results exceeds two times the repeatability standard deviation given in Clause 10, the test shall be repeated. 3.4 Blank determinations Carry out a blank determination without a sample following the same procedure and using the same amounts of reagents. Correct the results obtained for the analytical determination. 3.5 Sampling and sampling preparation Depending on the size of the raw material, a sample of at least 1 kg up to 10 kg shall be taken by the procedure described in ISO 11464, dried, crushed, reduced and ground to form a representative laboratory sample for analysis. The laboratory sample shall pass a sieve of 90 µm mesh size conforming to ISO 3310-1. The drying process shall be modified, if necessary, to accommodate samples known to contain high contents of volatile organic carbon. 3.6 General test principles In general, all the methods consist of the following procedures: a) decarbonation of the original limestone sample; b) purification of the carrier gas, if it is not of high purified quality; SIST EN 13639:2017

EN 13639:2017 (E) 7 c) oxidation of the organic carbon matter; d) purifying of the CO2 produced by oxidation; e) measurement of the CO2 content. 4 Reagents 4.1 General requirements Application of this standard involves the use of hazardous substances. There are national and European regulations and provisions on requirements for occupational health and safety. Use only reagents of analytical quality. References to water mean distilled water, or water of equal purity. Unless otherwise stated percent means percent by mass. cubic centimetre at 20 °C: ammonia solution

0,88 to 0,91 hydrochloric acid
1,18 to 1,19 hydrogen peroxide
1,11 nitric acid
1,40 to 1,42 phosphoric acid
1,71 to 1,75 sulfuric acid
1,84

The degree of dilution is always given as a volumetric sum, for example: dilute hydrochloric acid 1 + 2 means that 1 volume of concentrated hydrochloric acid is to be mixed with 2 volumes of water. 4.2 Ammonia solution (NH3 × H2O) 4.3 Calcium chloride, anhydrous (CaCI2) 4.4 Calibration reagent, metal For example iron with known carbon content. 4.5 Carbon dioxide in oxygen Concentrations, 0,95 vol.% and 19 vol.% 4.6 Carrier gases Air, oxygen, nitrogen or argon, free of carbon dioxide and hydrocarbons, depending on application. 4.7 Chromic acid Dissolve 5 g of chromium trioxide (4.8) in 10 ml of water. Add sulfuric acid (4.13) with stirring, until the chromium trioxide, which initially precipitates, is just re-dissolved. SIST EN 13639:2017

EN 13639:2017 (E) 8 WARNING — Chromic acid and its mixtures with sulfuric acid, may cause cancer. Also the vapour phase is dangerous. It is therefore necessary to take special precautions when working with chromic acids. 4.8 Chromium trioxide (CrO3) 4.9 Concentrated hydrochloric acid (HCI) 4.10 Concentrated hydrogen peroxide (H2O2) 4.11 Concentrated nitric acid (HNO3) 4.12 Concentrated phosphoric acid (H3PO4) 4.13 Concentrated sulfuric acid (H2SO4) 4.14 Copper (Cu), free of carbon 4.15 Copper oxide (CuO) Particle size of 0,6 mm to 1,2 mm 4.16 Dilute hydrochloric acid 1 + 5 4.17 Dilute nitric acid 1 + 9 4.18 Iron (Fe), free of carbon 4.19 Lead chromate (PbCrO4) 1 4.20 Magnesium perchlorate (Mg(CIO4)2), anhydrous Particle size 0,6 mm to 1,2 mm. 4.21 Magnesium sulfate, anhydrous (MgSO4) 4.22 Magnesium turnings according to Grignard (Mg) 4.23 Manganese dioxide (MnO2) Particle size of 0,6 mm to 1,2 mm. 4.24 Oxalic acid dihydrate (C2H2O4 × 2H2O) 4.25 Oxidation catalyst Ignited silver permanganate with a composition of approximately (AgMnO4).

1 Where substances are listed in REACH Regulation Annex XIV List of substances subject to authorisation, Article 56(3) of REACH provides a generic exemption from authorisation for listed substances for use in scientific research and development.

Scientific research and development includes use of listed substances as reagents for analysis and quality control purposes as long as use is carried out under controlled conditions and the amount does not exceed one tonne per year, per legal entity.

See FAQ [585] on ECHA's website. SIST EN 13639:2017

EN 13639:2017 (E) 9 4.26 Oxidizing mixture To 85 ml sulfuric acid (4.13) in a 250 ml beaker add in order 15 ml phosphoric acid (4.12), 20 g phosphorus pentoxide (4.28),15 g potassium dichromate (4.30), and 1 g potassium iodate (4.31). Carefully heat the mixture to about 170 °C maintaining the temperature for about 5 min and occasionally stirring with a thermometer. Allow the mixture to cool to room temperature and store it in a stoppered bottle. WARNING — Chromic acid, formed from mixtures of potassium dichromate and sulfuric acid, may cause cancer. Also the vapour phase is dangerous. It is therefore necessary to take special precautions when working with chromic acids. 4.27 Paraffin 4.28 Phosphorus pentoxide (P2O5) 4.29 Platinum (1 %) on alumina pellets (Pt), oxidation catalyst Particle size 3,2 mm. 4.30 Potassium dichromate (K2Cr207) 1) 4.31 Potassium iodate (KIO3) 4.32 Silver gauze (Ag) Wash commercially available silver gauze with ammonia solution (4.2), nitric acid 1 + 9 (4.17) and hydrogen peroxide (4.10). Rinse the gauze with water between each washing. 4.33 Sodium hydroxide (NaOH) 4.34 Sodium hydroxide (NaOH) on a high surface dark coloured siliceous carrier 4.35 Sodium hydroxide solution Dissolve 40 g sodium hydroxide (4.33) in water and make up to 1 000 ml. Store in a polyethylene container. 4.36 Sodium iodide (NaI) 4.37 Sodium iodide solution Add 10 ml of hydrochloric acid (4.9) and 150 g of sodium iodide (4.36) into a 1 l volumetric flask and dilute to 1 Iitre with water. 4.38 Zinc wool (Zn) 5 General apparatus 5.1 Balances Capable of weighing to an accuracy of ± 0,000 5 g and of ± 0,000 05 g for alternative methods 2 and 4, respectively. 5.2 Laboratory ovens Capable of being maintained at the following temperatures: (75 ± 5) °C and (105 ± 5) °C. SIST EN 13639:2017

EN 13639:2017 (E) 10 5.3 Crucibles Crucibles made of alumina of average porosity (30,5 ± 0,1) % and average density (2,38 ± 0,01) g/cm3. 6 Gravimetric method with wet oxidation (reference method) 6.1 Principle The carbon dioxide in the limestone is driven off by use of phosphoric acid (4.12). The remaining organic carbon is then oxidized to carbon dioxide with a strong oxidizing reagent mixture (4.26). The liberated carbon dioxide is absorbed on an inorganic carrier impregnated with sodium hydroxide (4.34) in a U-tube. The increase in mass is directly proportional to the organic carbon content in the sample. 6.2 Apparatus The apparatus is illustrated in Figure 1. To generate reduced pressure in the apparatus a small vacuum pump or an aspirator is used. The absorption tube (see Figure 1, no. 8) is filled approximately two thirds of its volume with the absorbent for carbon dioxide (4.34) and with magnesium perchlorate (4.20). The absorption tube is then inserted into the apparatus as shown in Figure 1 drawing through it about 4 l of carrier gas (4.6). At this time the apparatus should be checked for leaks by turning off the drying tower tap whilst keeping the small vacuum pump or the aspirator trap fully open. If leaks are absent the gas flow through the bubble counter stops completely. After checking for leaks, the taps of the absorption tube are to be closed, it is transferred to a desiccator for 10 min, weighed to an accuracy of 0,000 5 g (mu1), and reassembled as shown in Figure 1.

SIST EN 13639:2017
EN 13639:2017 (E) 11

Key 1 drying tower for carrier gas containing a carbon dioxide absorbent (4.34) 2 safety trap 3 inlet tube for the oxidising mixture (4.26) with glass rod stopper 4 150 ml round bottom distillation flask 5 100 ml sharp bottomed flask with 50 ml chromic acid (4.7) 6 absorption tube filled (in order upwards) with zinc wool (4.38), lead chromate (4.19) and silver gauze (4.32). The materials are fixed in place with cotton wool plugs 7 absorption tube filled with magnesium perchlorate (4.20), fixed in place with cotton wool 8 absorption tube with a total volume of approximately 11 cm3 containing, in order, absorbent for carbon dioxide (4.34), and magnesium perchlorate (4.20), fixed in place with cotton wool plugs 9 bubble counter, containing concentrated sulfuric acid (4.13) 10 vacuum Figure 1 – Apparatus for TOC determination by wet oxidation method WARNING — Use of acid resistant fume cupboards and acid resistant gloves is obligatory 6.3 Procedure Weigh, to an accuracy of ± 0,000 5 g, (1,00 ± 0,05) g of limestone (m1). Transfer to the 150 ml round flask, add 2 ml of water and 30 ml of phosphoric acid (4.12). Heat the mixture and boil gently for 4 min to expel the carbon dioxide. Cool the mixture and connect the flask to the apparatus. Substitute for the absorption tube (see Figure 1, no. 8) a glass tube and pass 2 I of carrier gas (4.6) through the apparatus to clear the system of any carbon dioxide. Fit the weighed absorption tube again to the apparatus and SIST EN 13639:2017

EN 13639:2017 (E) 12 check once more for leaks. Open the taps of the absorption tube2. Add approximately 30 ml of oxidizing mixture (4.26) to the flask through the inlet tube by lifting the glass rod and bring the sample mixture in the round bottom flask gently to boiling and keep at boiling for 4 min. Then remove the heater and whilst cooling pass approximately 3 I of carrier gas (4.6) through the system. Close the taps of the absorption tube. Transfer the absorption tube to a desiccator, allow to cool for 30 min and weigh to an accuracy of ± 0,000 5 g (mu2). 6.4 Calculation Calculate the total organic carbon content in percent using the formula: 29,27112×−=mmmTOCuu (2) where mu1

is the mass of the absorption tube before absorption of carbon dioxide in grams; mu2 is the mass of the absorption tube after absorption of carbon dioxide in grams; m1 is the mass of the sample in grams. 7 Gravimetric method with furnace oxidation (alternative method No. 1) 7.1 Principle The carbon dioxide in the limestone is driven off by use of hydrochloric acid (4.9) at approximately 130 °C. The insoluble residue is transferred to a platinum vessel. The remaining organic carbon is then oxidized in an oxygen atmosphere at approximately 900 °C and the liberated carbon dioxide is absorbed on an inorganic carrier impregnated with sodium hydroxide (4.34) in an absorption tube. The increase in mass is directly proportional to the organic carbon content in the sample. 7.2 Apparatus The apparatus is illustrated in Figure 2. A hot plate or sand bath, controlled at 140 °C is also needed.

2 When the white colour has extended along the first half of the tube, change the absorbent. SIST EN 13639:2017

EN 13639:2017 (E) 13

Key 1 oxygen cylinder (4.6) 2 drying tower containing carbon dioxide absorbent (4.34) 3 sample inlet of the quartz tube 4 short furnace, approximately 6 cm long 5 platinum vessel3 6 long furnace, approximately 26 cm long 7 silver gauze (4.32) 8 oxidation catalyst (4.25) 9 absorption tube, filled with magnesium perchlorate (4.20) 10 absorption tube with a total volume of approximately 11 cm3 containing, in order, absorbent for carbon dioxide (4.34) and magnesium perchlorate (4.20), fixed in place with cotton wool plugs 11 bubble counter, filled with paraffin (4.27) Figure 2 — Apparatus for TOC determination by gravimetric furnace oxidation method

3 The dimensions of the platinum vessel are approximately 5,0 cm x 0,8 cm x 0,8 cm. SIST EN 13639:2017

EN 13639:2017 (E) 14 7.3 Procedure 7.3.1 Filling the quartz tube Close the left-hand side outlet of the quartz tube with a 1 cm quartz wool plug. While holding the quartz tube in a vertical position, fill it with 6 cm of the oxidation catalyst (4.25), 1 cm quartz wool plug, 12 cm silver gauze (4.32), and 1 cm quartz wool plug. Compact the catalyst by slight vibration while filling the tube. Pack the silver gauze loosely. Position the quartz tube in the long furnace as shown in Figure 2. Heat the long furnace to (500 ± 20) °C, while passing oxygen through the tube. The flow rate of the oxygen shall be at least 7 ml/min. After 30 min the equipment is ready for the carbon determination.4 7.3.2 Preparing an absorption tube Fill a U-tube with carbon dioxide absorbent (4.34) and water absorbent (4.20) as indicated in Figure 2 no. 10. Keep the taps closed until the tube is fitted to the apparatus. Before each carbon determination, transfer the absorption tube into a desiccator and allow to stand for 10 min. Then weigh the absorption tube to an accuracy of ± 0,000 5 g (mu3). 7.3.3 Determination Weigh, to an accuracy of ± 0,000 5 g, (0,4 ± 0,1) g of limestone (m2) and transfer it into a dish consisting of perfluorinated plastic such as PFA or PTFE containing approximately 5 ml of water. The dish has a diameter of approximately 8 cm and a height of approximately 3 cm. Add slowly 10 ml of hydrochloric acid (4.9). At the end of the first intensive reaction, heat the dish on a hot plate with a surface temperature of approximately 140 °C to complete dryness. Allow oxygen to pass through the quartz tube and the drying tube (see Figure 2, no. 9) for approximately 15 min at a flow rate of at least 7 ml/min. Fit the weighed absorption tube (see Figure 2, no. 10) to the apparatus whilst opening its taps. Break up the sample residue and remove it from the wall of the dish with a PTFE rod, while still on the hot plate. Transfer the residue completely into the platinum vessel which is immediately introduced into the right-hand side inlet of the quartz tube, whilst oxygen is still passing through the tube. Close the inlet with a rubber stopper. Move the short furnace into position and heat to (900 ± 25) °C maintaining this temperature for 15 min. Then switch it off, but pass oxygen through the tube for another 20 min. After that close the taps of the absorption tube. Remove it, cool it in a desiccator, and weigh it to an accuracy of ± 0,000 5 g (mu4). 7.4 Calculation Calculate the total organic carbon content in percent using the formula: 29,27234×−=mmmTOCuu (3) where mu3 is the mass of the absorption tube before absorption of carbon dioxide in grams; mu4 is the mass of the absorption tube after absorption of carbon dioxide in grams; m2 is the mass of the sample in grams.

4 The catalyst filling in the tube, especially the silver gauze (4.32) is sufficient for about 15 carbon determinations and shall be renewed in time. SIST EN 13639:2017

EN 13639:2017 (E) 15 8 Infrared detection method with furnace oxidation (low temperature) (alternative method No. 2) 8.1 Principle The carbon dioxide in the limestone is driven off by use of hydrochloric acid (4.9) at approximately 130 °C. The residue is transferred to a platinum vessel. The remaining organic carbon reacts in an oxygen atmosphere at approximately 900 °C and is totally oxidized on a platinum catalyst at approximately 820 °C. The liberated carbon dioxide is measured by selective infrared spectrometric detector. The signal is quantified by chromatographic evaluation. 8.2 Apparatus A flow diagram in Figure 3 illustrates the apparatus and the principle of the furnace oxidation infrared detection instrument for determination of TOC. A hot plate or sand bath, controlled at 120 °C to 130 °C is also needed.

SIST EN 13639:2017
EN 1363
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