TOCmittaukset

TOCmittaukset refer to the measurement of total organic carbon in a sample and are widely used in environmental monitoring, drinking water analysis and industrial process control. In Finnish practice, TOCmittaukset describe the determination of organic carbon content in water, wastewater, soils and extract solutions, to assess organic matter presence and treatment performance.

The measurement principle involves converting organic carbon in the sample to carbon dioxide, which is then detected by a CO2 sensor. In water samples, inorganic carbon (for example from carbonates) is typically removed first by acidification and, if needed, purging of CO2. The remaining carbon is oxidized to CO2 by either high-temperature catalytic combustion or chemical oxidation (such as persulfate) under UV or heat. The CO2 produced is measured by infrared detectors, providing a reading for total organic carbon. Some methods distinguish dissolved organic carbon (DOC) by performing filtration prior to analysis, while TOC measurements may be reported for total carbon in the processed sample.

TOC analyses can report different fractions depending on preparation: TOC generally refers to the organic carbon in the sample after inorganic carbon removal and oxidation; DOC denotes the dissolved fraction obtained after filtration; some procedures also emphasize non-purgeable organic carbon in specific configurations. The choice of method depends on the matrix and the information required for process control or compliance.

Applications include monitoring drinking water quality, evaluating wastewater strength, optimizing water treatment processes, and environmental monitoring of rivers, lakes and soils. Quality control follows standardized practices from ISO and EPA and includes regular instrument calibration, use of reference materials, blanks, and replicate measurements to ensure accuracy and traceability.

Limitations include potential interference from inorganic salts, incomplete oxidation of refractory organics, and the influence of sample handling and turbidity. Proper sample preservation and preparation are essential for reliable results.