Feasibility Study on the Application of Automatic Potentiometric Titrator in the Measurement of Organic Carbon in Marine Sediments

The automatic potentiometric titrator has the advantages of being simple to operate and giving fast measurement results, which could reduce artifical influence due to manual operation. In this study, organic carbon content of marine sediments was determined by Automatic Potentiometric Titrator. In order to investigate if the Automatic Potentiometric Titrator could accurately determine the titration end-point, this method was compared with the national standard method (GB 17378.5-2007) in which the titration end-point was visually determined through color change. Results show that the detection limits of the automatic potentiometric titrator and manual methods were 0.029% and 0.086%, respectively. There are no significant differences between the two methods in titration end-point determination. However, the Automatic Potentiometric Titrator has better accuracy and precision than manual operation. Therefore, under certain circumstances, Automatic Potentiometric Titrator can take over the visual method to determine the titration end-point. It is also noteworthy that there are some problems in measuring real samples. For example, the Automatic Potentiometric Titrator might be unable to accurately determine the target titration end-point when there are complex electrical potential changes due to redox reactions and chelating interactions in the reaction system. On this occasion, the titration end-point can be determined visually.