Tandem on-line dialysis with a double and single dialyser in flow injection dialysis — Simultaneous determination of calcium and high chloride in industrial effluents

The on-line double membrane dialyser described previously was coupled in series to a single dialyser in the manifold of a flow injection system to include the determination of samples with a high chloride content simultaneously with calcium in industrial effluents from a single sample injection. 50 μl of industrial effluent samples are injected into a carrier stream and are simultaneously dialysed in the double on-line dialyser for chloride and calcium. The dialysed chloride sample zones are further directed to a second dialyser that is incorporated in series with the first dialyser. This enables laboratories to determine samples with a very high chloride content up to 60 g/l simultaneously with calcium by using an automated tandem on-line dialysis technique. The fast and reliable fully automated two-component flow injection procedure operated at a sampling frequency of 90 samples per hour and the results obtained for chloride and calcium in industrial effluents compared well with those obtained by standard methods.