End point detection of precipitation titration by scanometry method without using indicator

Abstract

A new methodology is developed for the accurate detection of precipitation titration end points without using any indicator. The validity of this new scanometry method was studied by detection of end points of the titration of halides in single, binary and ternary solutions. The cell containing precipitate was scanned with a flatbed scanner, and the image was analyzed in the CMYK color model by a written color analysis program. The results revealed that among the color values, the black value was suitable for the accurate detection of end points. To improve the accuracy of the end point detection, second derivative titration curves were obtained. The titration errors were acceptable, and were always less than 10%. The possibility of qualitative detection of end points, without using any image analysis, was also studied. The results indicated that in some cases, the end points could be visually detected from the cell image without applying any color analysis.