This method was developed by Axel Semrau. It combines two proven methods and enables a true total sulphur determination. In the ODOR total S II all sulphur compounds are converted into hydrogen sulphide (H2S) and subsequently measured on-line in the ODOR.

The first proven method for the determination of total sulfur is the gas chromatographic determination of different sulfur compounds and the summation of the measured sulfur compounds to total sulfur with the appropriate software. Especially suitable are gas chromatographs like the ODOR on-line, which only give signals for sulphur-containing components, but not for other substances in the gas. This method is well suited if only a few different sulphur compounds are present in the gas and therefore the calibration effort is low.

In the second method, all sulphur components are converted to H2S before detection. The conversion is done by means of a catalyst and with the addition of hydrogen (H2). The new ODOR total S II implements this method. In the ODOR total SII, a mixture of natural gas and hydrogen is produced via high-precision mass flow controllers (MFC). This mixture is passed over a hot catalyst, whereby all sulfur components are converted into H2S. This process also converts components such as carbon oxide sulfide (COS) to H2S.
The advantage of the process is that, due to the conversion of all sulfur components into one sulfur component (H2S), only one single-component calibration gas is required even for 100% total sulfur determination. This simplifies handling considerably and reduces costs.

Both methods (H2S measurement with the ODOR on-line / catalyst application for sulfur conversion) have been successfully used in practice for many years. The ODOR on-line has proven its robustness and reliability in field measurements of H2S, methyl mercaptan and ethyl mercaptan. With the ODOR total S II, the simple and automatic coupling of both methods in one procedure is now possible.