Dialysis for IC

Samples for ion chromatography need to be clear, clinically pure, with no bacteria or particles. Apart from the ions to be determined, however, most samples still contain large amounts of aggressive substances that make an analysis difficult. With 'MISP', the Metrohom inline sample preparation system, Metrohm now provides a range of possibilities and methods that allow users to automate sample preparation and make it considerably more efficient than was previously possible.

With the introduction of the Metrohm dialysis system, the determination of anions and cations in matrices such as fruit juice, milk, soil eluates or drilling oil emulsions, for example, can be carried out quickly, without any problem and without damaging the separating column.

Dialysis is neither filtration, nor extraction, nor digestion. Thanks to the special stopped-flow method, the ions from the sample solution diffuse through the dialysis membrane and enter the acceptor solution. After only a short time a concentration equilibrium is established between the sample solution and the acceptor solution. Whereas ions can pass through the membrane unhindered, larger particles - the matrix - are simply transported past the dialysis membrane. As a result matrix effects are reduced to the absolute minimum. The acceptor solution is then injected directly into the ion chromatograph and analysed as usual.

A high repeatability, long membrane working life, dialysis rates >98% and very low detection limits for anions and cations (lower µg/L range) make the Metrohm IC Dialysis system into a tool for mastering difficult applications.