重量法或容量滴定法是测定土壤或天然水中钙含量的经典方法。但容量法中有时由于样品混浊或带有颜色,使终点难以辨别,以致误差较大。近年来,随着离子选择性电极的发展,钙电极已用于土壤或水中的含钙量的测定。最早用于钙电极的电活性材料为有机磷酸盐(Ross,1967)。后来(Ammann et al.,1972) Gravimetric or volumetric titration is the classical method of determining calcium in soil or natural water. However, the volume method sometimes due to the sample cloudy or with a color, so difficult to distinguish the end point, resulting in greater error. In recent years, with the development of ion selective electrodes, calcium electrodes have been used to determine the amount of calcium in soil or water. The earliest electroactive material for calcium electrodes was organophosphates (Ross, 1967). Later (Ammann et al., 1972)