Study Of Constant-Current Coulometric Titration Measurement System

This paper presents the development of measurement system and the researching works of correspondence analysis methods .The theoretical bases of constant-current coulometric titration is Farad's law.In this paper, Farad's law is introduced.With analizing the constant-current coulometric titration test methods home and abroad, the automatic measurement system and the correspondence analysis methods were established.The expatiating upoon the working principle of the system was also presented.The constant-current control device, which designed and achieved by using auto-control technology, ensure the current constantly by comparing the output signal to the standard signal (standard cell and standard resistance).The softwares of system control and data process were also compiled. The control system would select one of the programme modules according to the sample-under-test by the computer. The coulometric titration can be carried out automatically. Thus, the control device and the software come into a reasonable measurement system.The stability of the constant-current device was examiated by two methods.The factors that affect the titration efficiency have been analyzed theoretically. They were under controll during the titration test. Thus the analyzing methods of Na2CO3 and EDTA CRM by coulometric auto-titration are formulated on the bases of the data of the measurement.The uncertainty analysis to the results shows that good purpose has been achieved.