Method for monitoring concentration of water borne substance in an aqueous medium

A method for monitoring the concentration of a water borne substance in an aqueous medium, comprising the steps of:

• introducing a defined amount of the aqueous medium into a gas circulatory system of an analytical apparatus comprising a high temperature reaction chamber and a measuring chamber, wherein the gas circulatory system extends through the high temperature reaction chamber and the measuring chamber, and wherein the introducing of the aqueous medium occurs upstream of the high temperature reaction chamber or into it;
• evaporating the aqueous medium in the high temperature reaction chamber;
• reacting the water borne substance with at least one reaction partner in the high temperature reaction chamber to a gaseous reaction product;
• registering the current value of a measured variable, which is a function of the concentration of the chemical species of the reaction product in the gas circulatory system, wherein the concentration of the chemical species of the reaction product in the gas circulatory system depends, on the one hand, on a time-dependent state of the gas circulatory system and, on the other hand, on the concentration of the substance in the aqueous medium;
• and
• ascertaining the concentration of the substance in the aqueous medium by applying the current value of the measured variable, wherein:
• in the ascertaining of the concentration of the substance in the aqueous medium, the contribution to the concentration of the chemical species of the reaction product in the gas circulatory system by the state of the gas circulatory system is ascertained on the basis of a model of the state, and a correction of the concentration of the chemical species of the reaction product in the gas circulatory system occurs on the basis of this contribution;
• for producing a clean state of the gas circulatory system, the gas circulatory system is purged, at given times or state dependently, with a carrier gas, which is free of the chemical species of the reaction product, except for possible negligible impurities and which is allowed to flow from a reservoir into the gas circulatory system;
• directly after the purging, registering the measured variable with the carrier gas and before new introducing of the aqueous medium, as a reference value, especially as a null point for describing a clean state of the gas circulatory system, for ascertaining the concentration of the chemical species of the reaction product in the gas circulatory system;
• and
• observing the time dependent behavior of the measured variable without introducing additional sample of the aqueous medium, following purging with the carrier gas, in order to win current data for modeling of the time dependent behavior of the contamination;
• wherein the modeling comprises a diffusion model describing the time dependent contamination by the chemical species of the reaction product getting into the gas circulatory system from the air in the surroundings of the analytical apparatus;
• and
• wherein the chemical species of the reaction product can get from the environment of the analytical apparatus as contaminant into the gas circulatory system, and the model describes time-dependent changing of the concentration of the chemical species of the reaction product in the gas circulatory system.

A method for monitoring the concentration of a water borne substance in an aqueous medium, comprising the steps of:

• introducing a defined amount of the aqueous medium into a gas circulatory system of an analytical apparatus comprising a high temperature reaction chamber and a measuring chamber, wherein the gas circulatory system extends through the high temperature reaction chamber and the measuring chamber, and wherein the introducing of the aqueous medium occurs upstream of the high temperature reaction chamber or into it;
• evaporating the aqueous medium in the high temperature reaction chamber;
• reacting the water borne substance with at least one reaction partner in the high temperature reaction chamber to a gaseous reaction product;
• registering the current value of a measured variable, which is a function of the concentration of the chemical species of the reaction product in the gas circulatory system, wherein the concentration of the chemical species of the reaction product in the gas circulatory system depends, on the one hand, on a time-dependent state of the gas circulatory system and, on the other hand, on the concentration of the substance in the aqueous medium;
• and
• ascertaining the concentration of the substance in the aqueous medium by applying the current value of the measured variable, wherein:
• in the ascertaining of the concentration of the substance in the aqueous medium, the contribution to the concentration of the chemical species of the reaction product in the gas circulatory system by the state of the gas circulatory system is ascertained on the basis of a model of the state, and a correction of the concentration of the chemical species of the reaction product in the gas circulatory system occurs on the basis of this contribution;
• the chemical species of the reaction product can get from the environment of the analytical apparatus as contaminant into the gas circulatory system;
• and
• the model describes time-dependent changing of the concentration of the chemical species of the reaction product in the gas circulatory system due to contamination;
• wherein an alarm signal is output, when change of the concentration of the chemical species of the reaction product in the gas circulatory system on the basis of contamination with respect to time exceeds a limit value.