An electrodialytic potassium hydroxide eluent generator suited to small bore ion chromatography

Abstract

An electrodialytic potassium hydroxide eluent generator (EDG) well-suited to small-bore (2 mm i.d.) ion chromatography (sIC) system is described. The basic configuration of EDG cartridge is much similar to that of conventional counterpart except lower void volume, which was measured to be ˜9 μL relative to ˜ 31 μL of conventional one. The corresponding dispersion volume was computed to be ˜58 μL and ˜106 μL, respectively. Lower void volume will improve the sharpness of a step gradient (or steeper rise curve), which is helpful to gradient elution. The device can bear the pressure up to at least 20.5 MPa and the effective KOH concentration that can be generated is ranging from 0.15 mM to 100 mM at the typical flow rate of sIC (0.4 mL/min). High purity of the produced KOH eluent and excellent running reproducibility of the device were observed, as indicated by the typical suppressed background (0.36 μS/cm) and <0.11% (or <0.23%) of the relative standard deviation of the retention times for common inorganic anions achieved under isocratic (or gradient) mode.