A new method of high-purity calcium citrate synthesized by using an on-line cation-resin column was proposed

and it was monitored by an automatic flow-injection electrochemical analysis system which was established on the basis of dynamic electrochemical technology with flow-through mini-type Na+ and Ca2+ electrodes.Simultaneous monitoring of the operational state of cation resin and the content of calcium citrate in effluent of the cation resin column was achieved by using this system.Through the investigation and optimization of the relevant factors

the total ionic strength adjustment buffer consisted of 80 mmol·L-1 tris

175 mmol·L-1 H3BO3

1 mmol·L-1 KCl and 0.025 mmol·L-1 CaCl2

sample injection volume was 150 μl

total flow rate was selected at 2.26 ml·min-1

length of mixing coil was 120 cm(I.D.0.5 mm).The linear determination ranges of the system were 2.0～1000 mmol·L-1 for Na+

0.2～50 mmol·L-1 for Ca2+

respectively

and the relative standard deviation was less than 0.68%(n=11).The detection limits were 1.12 mmol·L-1 for Na+

0.093 mmol·L-1 for Ca2+

respectively.