Figures of merit of the COOH-CNTs/Ag/NH₂-CNTs/GCE for the target drugs.

Figures of merits	AM	AT
Investigated range (μM to pM)	0.125–50.0	0.15–75.0
Linearity range (nM to pM)	6–50	9–75
LOD (fM)	77.6 fM	83.2 fM
LOQ (fM)	258.6	277
% RSD (reproducibility) (n = 6)	<0.9	<0.9
% RSD (repeatability) (n = 5)	<1.5	<1.5
% RSD (stability) (n = 8)	1.5	2.7
% RSD (anti interference ability) (n = 20)	2.2	3.1
% RSD (validity) (n = 6)	<3	<3
% Recovery (n = 12)	95–102	96–103