First Electrochemical Sensor (Screen-Printed Carbon Electrode Modified with Carboxyl Functionalized Multiwalled Carbon Nanotubes) for Ultratrace Determination of Diclofenac

Abstract

A simple, sensitive and time-saving differential-pulse adsorptive stripping voltammetric (DPAdSV) procedure using a screen-printed carbon electrode modified with carboxyl functionalized multiwalled carbon nanotubes (SPCE/MWCNTs-COOH) for the determination of diclofenac (DF) is presented. The sensor was characterized using optical profilometry, SEM, and cyclic voltammetry (CV). The use of carboxyl functionalized MWCNTs as a SPCE modifier improved the electron transfer process and the active surface area of sensor. Under optimum conditions, very sensitive results were obtained with a linear range of 0.1-10.0 nmol L −1 and a limit of detection value of 0.028 nmol L −1 . The SPCE/MWCNTs-COOH also exhibited satisfactory repeatability, reproducibility, and selectivity towards potential interferences. Moreover, for the first time, the electrochemical sensor allows determining the real concentrations of DF in environmental water samples without sample pretreatment steps.Keywords: screen-printed carbon electrode modified with carboxyl functionalized multiwalled carbon nanotubes; diclofenac; differential-pulse adsorptive stripping voltammetry; environmental water samples; HPLC with photo-diode array detection Materials 2020, 13, 781 2 of 15 to ground and surface water, causing their pollution. Low water temperatures and short days hinder the process of photolysis and the biodegradation of pharmaceutical preparations, which can cause adverse and unpredictable effects in the ecosystem. The main sources of pollution are factories and production plants, as well as hospitals, health centers, and practically every household. DF is one of the most commonly found ingredients in water, and its concentration is from 3.7 × 10 −11 to 1.4 × 10 −8 mol L −1 [2,3].Although the likelihood of any form of short-term human health risk after DF release into the environment is low, a study links the catastrophic decline of Gyps vulture populations across the Indian subcontinent to DF [4,5]. Generally, NSAIDs such as DF and ibuprofen, for example, have Log Kow values greater than three and may have the capacity to bioaccumulate in the tissues of organisms [6]. DF exhibits acute hepatotoxicity, causes changes in kidneys and gills in rainbow trout (O. mykiss) and exhibits acute toxicity to phytoplankton and zooplankton. Moreover, the possibility of synergetic effects with other pharmaceuticals or chemicals in the aquatic environment increases the environmental risk as well [7].There are many methods in the literature that allow for the determination of DF at various concentration levels. The most popular methods are spectrophotometry (determined DF concentrations: 6.8 × 10 −7 -8.4 × 10 −2 mol L −1 ), spectrofluorimetry (determined DF concentrations: 4.2 × 10 −7 -1.7 × 10 −4 mol L −1 ), calorimetry (determined DF concentrations: 4.6 × 10 −6 -2.7 × 10 −4 mol L −1 ), high-performance thin-layer chromatography (determined DF concentrations: 6.8 × 10 −7 -2.7 × 10 −6 mol L −1 ), and HPLC (determined DF concentrations: 1.7 × 10 −8 -1.4 × 10 −5 mol L −1 )...

Simultaneous Analysis of Paracetamol and Diclofenac Using MWCNTs-COOH Modified Screen-Printed Carbon Electrode and Pulsed Potential Accumulation

“…However, for the individual PA determination, the SPCE/CNFs should be used. These results perfectly confirm our previous research already described in the literature [ 2 , 4 ]. In the next step of the experiments, attempts were made to explain these differences between the size of PA and DF signals at the electrodes.…”

“…In the previously published papers [ 4 ], the electrochemical properties of SPCE and SPCE/MWCNTs-COOH were tested using CV studies in a solution of 0.1 mol L −1 KCl and 5.0 × 10 −3 mol L −1 K 3 [Fe(CN) 6 ]. However, the electrochemical properties SPCE/CNFs were not studied.…”

“…The basis of the mechanism of action is inhibition of cyclooxygenase, an enzyme involved in the synthesis of prostaglandins from cell membrane lipids. DF is used to treat inflammation and rheumatic (including rheumatoid arthritis) and non-rheumatic pain (including postoperative and traumatic pains, gout attacks, renal and hepatic colic, and dysmenorrhea) [ 3 , 4 ].…”

“…Screen-printed electrodes are cheap and ready-made systems with various modifications, and they are easily available commercially. Purchased electrochemical sensors do not require additional modifications; are immediately ready for use; and are characterized by high selectivity, sensitivity, and reproducibility [ 2 , 4 ].…”

A Screen-Printed Sensor Coupled with Flow System for Quantitative Determination of a Novel Promising Anticancer Agent Candidate

“…The modified sensor showed great improvement to the EIMTC reduction electrode process compared to the unmodified sensor (LOD: 5.0 × 10 −10 mol L −1 vs. 3.4 × 10 −8 mol L −1 and 1.7 × 10 −9 mol L −1 vs. 1.1 × 10 −7 mol L −1 , respectively). The reason for enhanced detection performance at the SPCE/CNFs is related to an increase in the number of active sites, as we showed earlier [ 14 , 15 ]. Furthermore, the electrochemical responses of EIMTC at the SPCE/CNFs were characterized by the CV technique and the results indicated that the reduction process of EIMTC is diffusion-controlled.…”