5. TOC in daily practice 5.1. TOC determination methods according to EN 1484 5.2. Determination of the purgeable organic carbon (POC) 5.3. TNb – total bound nitrogen 5.4. Kit for high-salt samples 5.5. Kit for small sample volumes 5.6. Kit for manual injections 5.7. Calibration with automatic dilution function 5.8. Blank value consideration in TOC analysis 5.9. TOC – measurement principle – catalytic combustion at 680°C 5.10. TOC-L – detection limit normal catalyst 5.11. TOC determination with wet chemical UV-oxidation 5.12. Silanisation of syringe – TOC determination of surfactant 5.13. TOC...

SHIMADZUExcellence in Science Application News NO. SCA-130-501 Sum parameter - Total Organic Carbon The EN 1484 standard “Guidelines for the determination of total organic carbon (TOC) and dissolved organic carbon (DOC)” defines various terms and parameters. ■ Definitions according to EN 1484 TC: Total carbon - the sum of organically bound and inorganically bound carbon present in water, including elemental carbon. TIC: Total inorganic carbon - the sum of carbon present in water, consisting of elemental carbon, carbon monoxide, carbon dioxide (also carbonates and hydrogen carbonates), cyanide,...

The TOC is calculated from the difference between TC and TIC: TOC = TC - TIC ■ Limitations of the difference method The inorganic carbon content may not be too high in comparison to the TOC. Error propagation can result in a high level of uncertainty for the calculated TOC value. The EN 1484 standard recommends that the TOC value, when using the differential method, should be higher or equal to the TIC value (TOC > TIC). Example: TC - Value = 100 mg/l (RSD = 2%) ± 2 mg/l (98 - 102 mg/l) IC - Value = 98 mg/l (RSD= 2%) ± 1,96 mg/l (96,04 - 99,96mg/l) TOC = 2 mg/l ± 3,96mg/l (- 1,96 - 5,96 mg/l) Due...

SHIMADZUExcellence in Science Application News NO. SCA-130-502 Sum parameter - Total Organic Carbon According to EN 1484, which contains the instructions for TOC determination, the POC (purgeable organic carbon) is the TOC content that can be expelled under the conditions of this method. This information is very unspecific and should be described here in more detail. The instruments in the TOC-L series can be extended with an option to include measurement of the POC parameter. The core feature of this option is the LiOH trap, which is placed in the flow line of the analyzer. For POC determination,...

Fig. POC-Calibration with IC-standard ■ System testing In POC analysis, it is of great importance that the LiOH trap functions perfectly. A test should, therefore, be carried out to confirm the efficiency of the CO2 trap. This test should be carried out each working day: An IC control solution (TIC = 1000 mg/L) is prepared and analyzed as a POC sample. For efficient functioning of the LiOH trap, the POC measuring result must be < 0.1 mg/L. ■ Example of a POC measurement Sample: Toluene in ultrapure water Toluene is a compound that is fully purgeable. In the addition method, the toluene sample...

SHIMADZU Excellence in Science Sum parameter - Total Organic Carbon Application NewsTNb - total bound nitrogen NO. SCA-130-503 Although nitrogen compounds are essential for nature and the environment, high nitrogen depositions can lead to problems. Nitrogen compounds enter the environment primarily through agricultural processes. Nitrogen-containing fertilizers constitute the largest proportion. But nitrogen compounds can also enter the environment via chemical industrial processes. Excessively high concentrations of nitrogen compounds in the environment can cause eutrophication of water bodies....

The conversion of the nitrogen containing compounds takes place via combustion in an oxygen atmosphere higher than 700 °C to nitrogen oxide, which reacts with ozone to activated nitrogen dioxide (NO2*). In the subsequent reaction to NO2, light quanta are emitted (chemiluminescence) that are measured by the detector. ■ Simultaneous TN determination using the TNM-L Based on the similar oxidation process, the TNb determination can be carried out simultaneously with the TOC measurement. For this application, the TNM-L option is installed on the top of the main TOC-L system. Subsequently, the gas...

Application News Kit for high-salt samplesNO. SCA-130-504 Compound Tab. Melting point of different salts Samples with high-salt loads generally are a problem for TOC analysis. The problem is less the conversion of organic compounds to CO2 than the effects of the salt on the catalyst. This leads to higher maintenance needs, as the salt can crystallize in the combustion system. In many applications for the instruments in the TOC-L and the TOC-4110/4200 series, the kit for salt-containing samples is an important component. It consists of a combustion tube of a special geometry and a unique mixture...

■ Endurance test To determine the performance of this option, a brine solution was measured in a long-term test. For this purpose, a 28 % NaCl solution (matrix adapted with a 15 % sulfuric acid solution and spiked to a 5 ppm TOC solution using a KPH solution) was injected 220 times. Initially, a blank value and a control standard with 10 ppm TOC were measured. The control standards were tested after 110 and 220 injections, respectively. The injection volume was 50 pL. The following figure shows the excellent reproducibilities and the stability of the measurement. ■ Recommended Analyzer / Configuration...

Application News Sum parameter - Total Organic Carbon Kit for small sample volumesNO. SCA-130-505 The instruments of the TOC-L series are designed to successively analyze many different types of samples of different concentrations. For the autosampler, sample trays for different sample numbers and sample volumes are available. To eliminate cross-contamination between analyses of the different samples, the number of rinsing steps can be defined in the software. There is usually enough sample volume available to rinse the tubing and the injection system of the TOC-L several times. Depending on...