1997 Volume 13 Issue 3 Pages 409-414
This work reports on the development, optimization and application of an FIA manifold to the sequential determination of calcium and magnesium cations in haemodialysis solutions. A tubular electrode sensitive to calcium and an atomic absorption spectrophotometer to measure magnesium were used as a detection processed. The system included a dialysis unit to enable sample dilution, since they presented high levels of the species to be determined. The system performance was optimized to obtain the maximum slope of calibration lines to Ca2+ and Mg2+ by means of the Taguchi Parameters Design (TPD). An L9(34) saturated orthogonal array led to the following optimized conditions: flow rate, 3.0ml/min; sample volume injected, 20μl; reactor length, 100cm; ionic strength, 3M. Under these conditions, the analytical procedure was robust and lead to reproducible results which were insensitive to variations in the glucose concentration. The developed system presents a high sampling rate (80 samples/h). The results obtained by the FIA system were compared with those given by the process of visual titration (10 samples/h) used as a reference method; it was found that both methods were in good agreement.
