Analysis of substances in minute concentrations - by freezing solution for concentration in first stage and analysing rest in second stage

An analysis of substances which are present in solutions in minute concns. by means of an analyser proceeds in two stages. The desired substance is first conc. by freezing most of the soln., utilising the phase equilibrium between liquid and solid phase. In the second stage, the liquid soln residue is analysed by the analyser. The method has a higher sensitivity than conventional methods. Traces of organic cpds. contained in a solution can thus be determined with a high accuracy.