Modification of Multiwalled Carbon Nanotubes by Dipyridile Amine for Potentiometric Determination of Lead(II) Ions in Environmental Samples

Table 1

Optimization of the electrode composition.

Electrode no.	Graphite powder (%)	Paraffin (%)	Di-pyridile amine	Unmodified MWCNTs (%)	Modified MWCNTs (%)	Slope (mV)	Linear range (mol L^−1)	𝑅^2
1	75	25	0	0	0	11.9±3.1	—	—
2	73	24	3	0	0	15.6±2.2	3.5×10^−6 to 1.0×10^−2	0.915
3	72	23	5	0	0	19.3±1.9	1.0×10^−6 to 1.0×10^−2	0.935
4	71	22	7	0	0	18.5±1.9	1.5×10^−6 to 1.0×10^−2	0.928
5	73	24	0	3	0	13.5±2.1	5.0×10^−6 to 1.0×10^−2	0.905
6	72	23	0	5	0	16.9±1.8	2.0×10^−6 to 1.0×10^−2	0.919
7	70	23	0	7	0	20.2±1.7	8.0×10^−7 to 5.0×10^−3	0.946
8	68	23	0	9	0	18.8±1.9	1.5×10^−6 to 1.0×10^−2	0.939
9	72	23	5	5	0	25.0±1.7	3.5×10^−7 to 2.5×10^−3	0.975
10	67	23	5	7	0	28.9±1.1	7.5×10^−8 to 2.5×10^−3	0.995
11	65	23	5	9	0	27.8±1.5	1.5×10^−7 to 2.5×10^−3	0.979
12	73	24	0	0	3	24.7±1.7	5.0×10^−7 to 2.5×10^−3	0.966
13	72	23	0	0	5	26.3±1.5	2.0×10^−7 to 2.5×10^−3	0.970
14	70	23	0	0	7	28.6±1.2	9.5×10^−8 to 2.5×10^−3	0.990
15	67	23	0	0	9	28.0±1.3	1.0×10^−7 to 2.5×10^−3	0.982