Determination of Calcium Ion Concentration

The electrode potential of ISEs depends on the activity of the detected ion. If the adsorption or complex formation of the ion decreases the activity of the free ion, then the potentiometric method will give a smaller concentration value than another method that measures the total ion concentration. [Pg.197]

Calcium ion concentration is an important property of apples. It seriously affects the post-harvest marketing and storage value of it. Usually, the measurement of the calcium concentration in fruits like apple is made by drying and burning the fruit and analyzing the ashes with atomic absorption spectroscopy. Knee and coworkers [65] observed that the considerable part of calcium ions in the apple is bound to cell walls. [Pg.197]

Gao et al. [66] investigated the accuracy of calcium measurements in simulated milk ultrafiltrate and skim milk samples. They realized that the free calcium ion concentration is smaller in the sample than the total one owing to the ionic complex formation by phosphate, chloride, and citrate ions. Therefore, they recommend new standard solutions for calibration with ionic profile nearly the same as samples. Using those calibrating solutions, the systematic error could be substantially reduced. [Pg.197]

Big Chemical Encyclopedia