BS EN 15936:2012 pdf download
BS EN 15936:2012 pdf download.Sludge, treated biowaste, soil and waste- Determination of total organic carbon (TOC) bydry combustion.
7.3 Purging unit for TIC determination, for Method A only.
7.4 Crucibles or boats, made of e.g. ceramics, silica glass, silver or platinum.
NOTE Tin and nickel cn.icibles are not aod-resistant. Tin auctles are suitable only for Method A.
8 Sample pretreatment
Pretreat the sample according to EN 16179 or EN 15002, if not otherwise specified.
For soil, dried samples shall be used.
Moist or paste-like samples may be mixed with aluminium oxide (6.9) until granular material is obtained and then be comminuted. In this case, the ratio of aluminium oxide to sample shall be considered In the calculation of TOC (according to 9.4 or 10.4).
If samples contain — depending on the accuracy of the method — negligible amounts & volatile compounds except water, the samples may be dried.
9 Procedure – Method A (Indirect method)
9.1 Determination
9.1.1 General
The mass of the test portion should be as large as possible and shall be chosen so that the liberated quantity
of carbon dioxide lies within the working range of the equipmentlcalibration.
9.1.2 Determination of the TC
The sample prepared according to Clause 8 is weighed into a suitable vessel (7.4). To minimize carbon blank values the vessel may be pre-treated by heating (in a muffle furnace or the TC apparatus itself)!
The sample Is burned or decomposed in a flow of carrier gas containing oxygen (6.13).
The combustion temperature shall be high enough to convert all carbon completely to carbon dioxide. For samples containing carbonates, which are difficult to decompose. e.g. berium carbonate, the release of the carbon dioxide may be Improved by Increasing the temperature or by the use of modifiers. e.g. tin, copper.
The temperature range of commercially available instruments is between 900 C and 1 500 C.
During the combustion of reactive samples explosion or fuming may be prevented by covering the sample with inert material e.g. silica sand.
The carton dioxide released during the analysis is measured using one of the detection methods infrared spectrometry, gravr’ietry, coulometry. conductometry. thermal conductivity detection, flame lonisatlon detection after reduction to methane, or other suitable techniques. and is expressed as carbon.
9.1.3 Determination of the TiC
The sample prepared according to Clause 8 is weighed into the purging unit (7.3).
The system is closed gas-tight and flushed with carrier gas until no more carbon dioxide from ambient air is present. Then acid (6.12) is added and the carbon dioxide is stripped by purging or stirring and/or heating. The released carbon dioxide is transferred to the detector by the carrier gas.
The addition of anti-foaming agents, e.g. silicone cxl. may be helpful in the case of strongly foaming samples, The addition of wettin9 agents. e.g. surtactants, may Improve wetting of the surface of the sample.
The carbon dioxide released duflng the gas evolution is immediately measured using one of the detection methods infrared spectrorneiry, gravimetry, coulometry, conductometry. thermal conductivity detection, flame ionisation detection after reduction to methane, or other suitable techniques and is expressed as carbon.
TIC may alternatively be determined according to ISO 10693.
Samples containing persistent carbonates (e.g. concrete, cement) require treatment with hot acid for complete
release of carbon dioxide.
9.2 CalIbration
If a relative method Is used for detection. e.g. infrared detection, calibration is necessary.
Examples of calibration substances suitable for TC are calcium carbonate (61). potassium hydrogen phthalate (6.4). acetanilide (6.5). atropine (66), spectroaphic graphite powder (6.7).
Sodium carbonate (62) and Na6-EDTA (6.3) as well as all compounds with EDTA-structure shall not be used for TC-calibration as they are used as control substances.
Sodium carbonate (6.2) or calcium carbonate (6.1) are suitable for the calibration of TIC. Other calibration substances may be used provided their suitability is checked.
The following procedure snould be applied for calibration:
Establish the preliminary working range
Measure a minimum of five standard samples The concentration of these standard samples shall be distributed evenly over the working range.
— Calculate mean values for each concentration
Carry out a linear regression analysis with the mean values and test the lineaflty of the calibration function (see also ISO 8466-1).
