First Screen-Printed Sensor (Electrochemically Activated Screen-Printed Boron-Doped Diamond Electrode) for Quantitative Determination of Rifampicin by Adsorptive Stripping Voltammetry

Abstract

In this paper, a screen-printed boron-doped electrode (aSPBDDE) was subjected to electrochemical activation by cyclic voltammetry (CV) in 0.1 M NaOH and the response to rifampicin (RIF) oxidation was used as a testing probe. Changes in surface morphology and electrochemical behaviour of RIF before and after the electrochemical activation of SPBDDE were studied by scanning electron microscopy (SEM), CV and electrochemical impedance spectroscopy (EIS). The increase in number and size of pores in the modifier layer and reduction of charge transfer residence were likely responsible for electrochemical improvement of the analytical signal from RIF at the SPBDDE. Quantitative analysis of RIF by using differential pulse adsorptive stripping voltammetry in 0.1 mol L^-1 solution of PBS of pH 3.0 ± 0.1 at the aSPBDDE was carried out. Using optimized conditions (E_acc of -0.45 V, t_acc of 120 s, ΔE_A of 150 mV, ν of 100 mV s^-1 and t_m of 5 ms), the RIF peak current increased linearly with the concentration in the four ranges: 0.002-0.02, 0.02-0.2, 0.2-2.0, and 2.0-20.0 nM. The limits of detection and quantification were calculated at 0.22 and 0.73 pM. The aSPBDDE showed satisfactory repeatability, reproducibility, and selectivity towards potential interferences. The applicability of the aSPBDDE for control analysis of RIF was demonstrated using river water samples and certified reference material of bovine urine.

Keywords: differential pulse adsorptive stripping voltammetry; electrochemically activated screen-printed boron-doped diamond sensor; first screen-printed sensor for rifampicin determination; river water and urine samples.

Figure 1

(A) Voltammograms of 0.2 nM rifampicin (RIF) in 0.1 M phosphate buffer saline (PBS) of pH 7.5 obtained at the bare screen-printed boron-doped diamond electrode (SPBDDE) (a), electrochemically activated in 0.1 M acetate buffer of pH 4.0 containing 10 mM H₂O₂ SPBDDE (b) and electrochemically activated in 0.1 M NaOH SPBDDE (c). The differential pulse adsorptive stripping voltammetric (DPAdSV) parameters: Eacc of −0.25 V, tacc of 60 s, ΔE_A of 50 mV, ν of 100 mV s⁻¹ and t_m of 10 ms. (B) Nyquist plots of SPBDDE (a) and aSPBDDE (b).

Figure 2

Cyclic voltammograms recorded in a solution of 0.1 M KCl containing 5.0 mM K₃[Fe(CN)₆] at the bare SPBDDE (A) and electrochemically activated in 0.1 M NaOH SPBDDE (B). (C) Dependence between anodic peak currents and the square root of the scan rates for the bare SPBDDE (a) and aSPBDDE (b), ν range of 50–400 mV s⁻¹.

Figure 3

(A) Scanning electron microscope (SEM) images and (B) optical profiles of SPBDDE (a) and aSPBDDE (b).

Figure 4

Influence of pH value (A) and concentration of the PBS solution of pH 3.0 ± 0.1 (B) on RIF peak current. The DPAdSV parameters: Eacc of −0.25 V, tacc of 60 s, ΔE_A of 50 mV, ν of 100 mV s⁻¹ and t_m of 10 ms.

Figure 5

(A) Cyclic voltammograms recorded in 0.1 M solution of PBS (pH 3.0 ± 0.1) containing 5.0 µM RIF at different scan rates, (B) the dependence between Ip and ν^1/2, (C) dependence between log Ip and log ν for ν from 15 to 500 mV s⁻¹.

Figure 6

Influence of Eacc (A) and tacc (B) on the analytical signal of 1.0 and 0.5 nM RIF, respectively.

Figure 7

Effect of ΔE_A (A), ν (B) and t_m (C) on analytical response of 0.5 nM RIF. The DPAdSV parameters: E_acc of −0.45 V and t_acc of 120 s.

Figure 8

Histogram bars of the RIF peak current in the presence of interferents.

Figure 9

(A) DPAdSV curves recorded at the aSPBDDE in the PBS solution of pH 3.0 ± 0.1 containing increasing concentrations of RIF: (a) 0.002, (b) 0.005, (c) 0.01, (d) 0.02, (e) 0.05, (f) 0.1, (g) 0.2, (h) 0.5, (i) 1.0, (j) 2.0, (k) 5.0, (l) 10.0, (m) 20.0 nM. (B) DPAdSV curves for the RIF concentration: (a) 0.002, (b) 0.005, (c) 0.01, (d) 0.02 nM. (C) Calibration plot of RIF. The DPAdSV parameters: Eacc of −0.45 V, tacc of 120 s, ΔE_A of 150 mV, ν of 100 mV s⁻¹ and t_m of 5 ms.

Figure 10

DPAdSV curves obtained for the determination of RIF in Bystrzyca river water sample (A): (a) 1 mL of sample + 0.1, (b) as (a) + 0.1, (c) as (a) + 0.2 nM RIF and bovine urine sample (B): 1 µL of sample + 0.1, (b) as (a) + 0.1, (c) as (a) + 0.2 nM RIF. The DPAdSV parameters: Eacc of −0.45 V, tacc of 30 s, ΔE_A of 150 mV, ν of 100 mV s⁻¹ and t_m of 5 ms.