Analytical Sciences


Abstract − Analytical Sciences, 28(8), 781 (2012).

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.