Bjorvatn K, Mørch T
Acta Odontol Scand. 1979;37(5):259-65. doi: 10.3109/00016357909004695.
Ion selective potentiometry is widely used for analytical purposes in biologic research. The Ca selective electrode offers an inexpensive and easily handled means for studying ionized calcium. It does not affect the process studied, and may, for example, combined with an automatic recorder, give running information on dynamic systems. The calcium electrode responds in accordance with the Nernst equation and has a theoretical range of 1--10(-6) M Ca2+. The electrode is influenced by changes in temperature, in pH and also in concentration of buffer solution. The Ca sensitive membrane is adversely affected by acetic acid but tolerates lactate/lactic acid buffers. Best linearity in calibration curves for Ca2+ in lactate buffers is found in concentrations from 10(-4) M to 10(-2) M Ca. In a 5% Na lactate/lactic acid buffer, pH 5, with 0.5 M KNO3 as an ionic strength adjuster, a straight calibration curve, Nernstian slope factor 27 mV/decade, is found from 10(-4) to 1 M Ca.
离子选择性电位分析法在生物学研究中广泛用于分析目的。钙选择性电极提供了一种廉价且易于操作的手段来研究离子化钙。它不会影响所研究的过程，例如，与自动记录仪结合使用时，可以提供动态系统的实时信息。钙电极根据能斯特方程响应，理论测量范围为1 - 10⁻⁶ M Ca²⁺。该电极受温度、pH值以及缓冲溶液浓度变化的影响。钙敏感膜会受到乙酸的不利影响，但能耐受乳酸/乳酸盐缓冲液。在乳酸盐缓冲液中，Ca²⁺校准曲线的最佳线性范围是Ca浓度为10⁻⁴ M至10⁻² M。在pH为5的5%乳酸钠/乳酸缓冲液中，以0.5 M硝酸钾作为离子强度调节剂，可得到一条从10⁻⁴到1 M Ca的直线校准曲线，能斯特斜率因子为27 mV/十倍浓度变化。
