摘要

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 mu L, 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 mrnol 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.