ABSTRACT
An electrolyte cathode atmospheric glow discharge atomic emission spectroscopy(ELCAD-AES) has been developed to determine the hardness of water. By the standard curves of Mg and Ca, the concentration curves of Mg and Ca measurement were obtained. The limits of detection of Mg and Ca were 0.2 and 0.8 mg/L, respectively. The precision and recovery were experimentally elucidated, which indicated that the homemade ELCAD-AES system has a good performance. Finally, practical water samples such as tap water, boiled tap water, ground water, boiled ground water and lake water were analyzed by the method. The results were in agreement with those by the EDTA titration. This demonstrates that ELCAD-AES has the capacity for on-line determination of water hardness.