Simultaneous Determination of K+, Ca2+, Na+ and Cl- in Radish by Ion Selective Electrode Combined with Flow-Injection Asynchronous Injection

A rapid and accurate method for simultaneous determination of K+, Ca2+, Na+ and Cl- in radish was established by using ion selective electrode coupled with flow-injection asynchronous injection. The optimum conditions were as follows: the flow rate was 2.43 mL·min-1; the total ion strength adjustment buffer consists of 80 mmol·L-1 of Tris-H3BO3 (pH 6.00), 0.05 mmol·L-1 of Na+, 0.5 mmol·L-1 of K+, 0.01 mmol·L-1 of Ca2+ and 0.57 mmol·L-1 of Cl-; the reaction coil length was 50 cm; the sampling volume was 220 μL; the pH of the mixed standard solution was 6.00. The linearity ranges of K+, Ca2+, Na+ and Cl- were 10-70, 0.5-7.0, 10-36, 21-119 mmol·L-1, respectively, with detection limits (3s/k) of 5.0, 0.2, 5.0, 10 mmol·L-1, respectively. Recovery rates obtained by standard addition method were in the range of 92.8%-110% and RSD (n=11) was less than 2.0%.