Metrohm Combines Conductivity and pH measurement with Inline Dilution and Subsequent Ion Chromatography (IC)

In combination with Metrohm Inline Dilution (MIDT), this system makes sure that the ionic concentration of the solution is ideal for the subsequent analysis by IC. Moreover, by including inline pH measurement in this procedure, Metrohm enables users to determine the most important parameters in water analysis on a single system.

Excessive ionic concentrations are a challenge in ion chromatography as they are likely to stress the column leading to incorrect results. To prevent this, solutions are usually diluted prior to injection in the ion chromatograph. The conductivity of the solution is usually taken as a measure to determine the optimum dilution factor. However, conductivity measurement and the dilution itself are still very often performed manually – something that is both laborious and time-consuming.

The Metrohm technique presented here combines all of these steps in a single system. To this end, sample is transferred into the measuring cell equipped with a 5-ring electrode of an 856 Conductivity Module by means of an 858 Professional Sample Processor and an 800 Dosino. From the measured conductivity the software calculates the required dilution factor. Subsequently, the sample is transferred to an external vessel, exactly diluted there and then injected in the ion chromatograph for analysis.
    
Apart from the conductivity, the pH value is determined in almost any water analysis. The Metrohm system presented here enable users to simply determine the pH value in the original solution by including an 867 pH module in the system setup. As there is no manual work required the pH measurement is fast. Alternatively, the pH value can also be determined in the solution after it has been diluted. The pH measurement is carried out to protect the column as there are some columns with only a limited pH working range. This means that sample will only get injected in the ion chromatograph, if the pH value is within the pH working range of the column.
Ultimately, the MagIC Net™ software of the 850 Professional IC presents the results of the conductivity and pH measurement together with the results of the ion chromatographic analysis in a detailed report.