Metrohm has unveiled an inline sample preparation unit (MISP) for full automation of sample preparation.
The sample preparation unit (SPU) allows for the inline neutralisation of both bases and acids for anion analysis of difficult sample matrices.
MSM (cation exchanger) technology is used with an increased capacity, and ensures reliable analysis of difficult samples: for example, the determination of anions in concentrated alkalis.
The module can also be used for the removal of interfering cations that can disturb the baseline in anion analysis.
Elimination of the interfering matrix takes place inline, with the regeneration and rinsing carried out in parallel offline.
The capacity of SPU is unlimited, as the unit is automatically regenerated and rinsed after each determination.
The sample solution enters the SPU via a loop injector and is rinsed with ultra-pure water.
Using this setup, the sample cations are exchanged: for example, for protons (H+).
If the sample is sodium hydroxide, then water is formed by neutralisation.
The sample is then transferred to an anion pre-concentration column, where the trace anions to be determined are retained; then elution takes place, with the eluent in a counter-flow direction to transfer the anions to the separating column, where they are separated and determined.
For acidic samples, the setup can be altered so that a lithium salt is used to rinse the sample.
Now the cation exchanger is in the lithium form, and when the sample (hydrochloric acid, for example) passes over the SPU, the acids are converted to their lithium salts and the pH of the sample is increased.
The anions are retained on a pre-concentration column and analysed in the same way as for neutralisation.
The Metrohm inline sample preparation unit is integrated directly into the 850 Professional IC instrument (2.850.2190), or the 833 module can be added retrospectively to older Metrohm and third-party instruments.
