Cation exchange chromatography with both unsuppressed conductivity detection and indirect photometric detection (IPD) modes were used for the separation and detection of inorganic cations. Salt of weak base diphenylamine has been used as an eluent for several cations both with unsuppressed conductivity detection and IPD. 4-aminodiphenylammonium chloride possess ion exchange capability, chromatographic selectivity and large molar absorptivity. 4-aminodiphenylammonium chloride showed a good chromatographic performance toward the analysis of the cations (Lithium, Barium, Iron II and Iron III ) using conventional HPLC equipment with either conductivity or indirect UV detectors. The analysis of these cations using (1×10-7 M) 4-aminodiphenylammonium chloride at pH 5.80 in 5% DMSO, with Dionex Ion Pac CS3 Column, and 1ml/min flow rate was achieved with unsuppressed column conductivity and IPD at 342.5 nm detection. Chromatogram of a separation mixtures containing four cations (Li+, Ba+2,Fe+2 and Fe+3) and other mixture have given well separated peaks using IPD technique. The capacity factor K` for the analyzed cations were ranged from (1.70-2.44), peak symmetries was ranged from (1.11-1.41) and resolution with an average value of (1.310) was optained. The average RSD for tR was 0.435%. The average recovery was 93.1075 % and the average relative error percentage was 6.77 % with unsuppressed conductivity detection . However, using IPD, the peak symmetry was ranged from(1.30-1.54), and an average value of resolutin of 1.41 which indicate a good chromatographic performance. The RSD in tR averaged 0.351 %. The average value of recovery was 95.975 %. Calibration curve for all analyzed cations were linear from their detection limit to at least 10 ppm. The correlation coefficients for the linear calibration curve were ranged from (0.9991, 0.9998) with both detection techniques. The detection limit was ranged from (0.025, 0.1) ppm for unsuppressed conductivity detection compared to (0.02, 0.05) ppm for IPD.
