Analytical Sciences

A Negative-pressure Flow-injection Micro-electrode System for Rapid and Simultaneous Determination of Four Electrolytes in Human Serums

Yong-Sheng LI,* Lei ZHOU,* Hui-Sheng ZHANG,** Zhen-Yao LAI,* and Xiu-Feng GAO***

*School of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China
**School of Information Technology, Shenzhen University, Shenzhen 518060, P. R. China
***West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu 610041, P. R. China

An automatic system for simultaneous determination of K⁺, Na⁺, Cl⁻ and Ca²⁺ in serums was established on the basis of a negative-pressure flow-injection using micro-electrodes, and parameters of the system were optimized. The total ionic strength adjustment buffer consisted of 0.25 mmol L⁻¹ K⁺, 48.6 mmol L⁻¹ Na⁺, 2.56 mmol L⁻¹ Cl⁻, 0.25 mmol L⁻¹ Ca²⁺ and 23 mmol L⁻¹ Na₂B₄O₇–H₃BO₃; the flow rate was 1.58 mL min⁻¹, the sampling volume was 45 μL, and the mixing coil length was 30 cm. The system could conduct 480 detections h⁻¹, and its RSD was less than 1.6%. Recoveries were 97.3 – 103.6%, and linear responses were 2.0 – 22.0 mmol L⁻¹ for K⁺, 89.6 – 253.0 mmol L⁻¹ for Na⁺, 20.1 – 248.2 mmol L⁻¹ for Cl⁻, and 0.35 – 10.0 mmol L⁻¹ for Ca²⁺, respectively. The ion concentration ranges were in ranges of human serum electrolytes. The system features minimized sorption of fibrin in sensors and prolonged sensor life.

J-STAGE: View this article in J-STAGE