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Special impurity analytics


Gas impurity analysis

Sulphur compounds

For sulphur containing compounds, we can analyze hydrogen sulfide (H2S) and carbonyl sulfide (COS) with gas chromatographic (GC) method. The GC analysis is conducted with sulphur selective Flame Photometric Detector (FPD) and our main analytical range is in 0 - 10 000 ppm. In addition to H2S and COS, it is possible to analyze sulphur dioxide (SO2), methyl mercaptan (CH3SH), dimethyl sulphide (CH3SCH3) and tetrahydrothiophene (THT, natural gas component) concentrations.

Sulphur compounds need special care from sample gathering and analysis as they tend to absorb to the transfer lines and storage containers. Furthermore, the sample analysis should be conducted fairly rapidly after sample collection (within a day).

Ammonium nitrogen (NH4-N) compounds

Nitrogen compound analysis, such as organic, ammonium and ammonia nitrogen is conducted with Kjeldahl distillation. This method can be used, for example, product gas, condensation water and waste water samples. VTT has developed a sample gathering method for ammonium nitrogen collection so that the sample is stored in a sulphuric acid solution and in analysis this solution is distillated directly without burning the ammonia.

Cyanide (CN-) compounds

In this method, a cyanide defined as the CN-groups that can be analyzed as cyanide ions (CN-). In the VTT’s cyaniden sample collection method, the cyanide compounds are collected into a sodium hydroxide (NaOH) solution. In addition to cyanide ion concentration, the analysis contains cyanide released from metal cyanides and complexes as hydrogen cyanide. Hydrogen cyanide is released when sample is reacted with strong sulphuric acid solution.