Preconcentration of an analyte dialysate in a flow-injection system

Preconcentration of an analyte dialysate was studied in a flow-injection system where hyphenation of the dialysis/preconcentration was done on-line. The dependence of the combined dialysis/preconcentration process on a number of variables was evaluated and optimised. As timing played a very important role in the whole system, a time regulated system from a computer was employed to control various functions of the system. The system was applied to the determination of copper in food supplements containing vitamin-mineral conditioners for dogs and cats. Suitable results were obtained from a calibration curve between 0.5 and 5 mg/l of soluble copper with a detection limit of 0.295 mg/l. The values obtained by the hyphenated dialysis/preconcentration/FIA system compared favourably with the standard manual atomic absorption spectrometric method and the value of 0.05% (m/m) given by the producers. A relative standard deviation of 5.74% was obtained.