potentiometric determination of la(iii) using chitosan modified carbon paste electrode with an experimental design

In this work, d-optimal mixture design was applied as an experimental design to screen and optimize the effect of the composition of a carbon paste on its performance. in this study, chitosan was offered as a ligand for the determination of la(iii) with the carbon paste electrode. in the fabricated sensor, the greatest nernstian slope was achieved on the optimized mixture composition by experimental design: 60.00% w/w powder graphite, 1.53% w/w multi-walled carbon nanotubes (mwcnts), 29.79% w/w paraffin oil, and 8.68% w/w chitosan. mwcnt was used for increasing the electrode response to la(iii). the quadratic fitting pattern based on d-optimal model was used to find the desirability functions of the suggested design to assess the cross-interferences and the interactions between the factors. the fabricated sensor for determining the la(iii) ions demonstrated a maximum nernstian slope equal to 19.70 mv.decade^-1 along a linear range from 1.0×10^−6 to 1.0×10^−2 mol/l^−1 and detection limit of 10^−6 mol/l^-1. the designed sensor was successfully tested in the ph range of 2-9 with suitable selectivity, fast response time (about 30 s) and long lifetime (over 2 months) was obtained without any deviation. the offered electrode was used successfully as an indicator in the potentiometric titration of la(iii) with edta.