Electroanalytical thread-device for estriol determination using screen-printed carbon electrodes modified with carbon nanotubes

Abstract

Microflow systems are powerful analytical tools that explore similar principles of typical flow injection analysis driven to in a microfluidic device. Generally, microfluidic devices can promote a low consumption of reagents and samples, high speed of analysis and possibility of portability. Several advances have been reached applying a simple and low cost device based on cotton thread as microfluidic channel where the transportation of solutions is based on capillary force helped by gravity. In the present work, we have demonstrated the versatility of thread-based electroanalytical devices (μTED) constructed using a cotton thread as the solution channel and screen-printed electrodes (SPE) surface modified with carbon nanotubes (CNT) as electrochemical detectors for the amperometric determination of estriol hormone in pharmaceutical samples. The parameters involved in the amperometric detection and microflow system were studied and optimized, using the best experimental conditions (flow rate of 0.50 μL s−1, 10 mm of analytical path, 2.0 μL of volume of injection and potential of detection of 0.75 V) a linear response was observed for concentration range (LDR) of 1.0 to 1000 μmol L−1 with limits of detection (LOD) and quantification (LOQ) of 0.53 μmolL−1 and 1.77 μmolL−1, respectively, and frequency of injection of 32 per hour. The proposed methodology was applied for determination of estriol in commercial samples and results were compared with those provided by spectrophotometric method (official methodology). The obtained results are in agreement at a 95% of confidence level.

An Overview of Recent Electroanalytical Applications Utilizing Screen‐Printed Electrodes Within Flow Systems

“…Finally, SPEs were also used successfully for implementation of amperometric detection within FIA microfluidic devices based on cotton threads. [76][77][78] The SPEs were easily adapted to these FIA microfluidic devices and used for detection of estriol (LOD = 0.53 μmol L À 1 ) in water samples, [76] phenol (LOD = 0.003 μmol L À 1 ) in tap water" [77] and antioxidants such as gallic (LOD = 1.5 μmol L À 1 ) and caffeic acid (0.8 μmol L À 1 ) in wine. [78] These excellent LODs were obtained with minimal consumption of reagents (flow rate � 0.7 μL s À 1 ) and samples (injection volume = 2.0 μL).…”

“…Tap water AuSPE modified with SAM and covered of chitosan 1.6 40 [58] Electroactivity of NPs NR SPGE NR NR [59] Isoniazid PF and blood serum SPCE 0.003 50 [60] Arsenic(III) Drinking water SPCE modified with AuNPs and nanofiber-chitosan 0.15 72 [61] Salmonella typhimurium Milk SPCE 7.7 cells mL À 1 NR [ [75] Estriol PF SPCE 0.53 33 [76] Phenol Drinking water SPCE modified with CN/AuNPs/tyrosinase 0.003 30 [77] Gallic acid Caffeic acid Wine SPCE 1.5 08 43 [78] [a] AF: analytical frequency (injections h À 1 ); AuSPE: gold SPE; LOD: limit of detection; NR: not reported; PF: pharmaceutical formulation; SGPE: screen-printed graphite electrode; SPCE: screen-printed carbon electrode; MWCNTSPE: multiwalled carbon nanotube SPE; WE: working electrode; TvL: Trametes versicolor Laccase. and injection valves.…”

“…If the internal volume of the BIA cell is large, a great number of injections can be made (high dilution inside the cell) without the need to touch the electrodes or exchange the electrolyte solution inside the cell (useful for portable applications). [75,76] In 2014, the combination of a BIA system and SPEs (BIA-SPE) was proposed for the first time. [19] The portable characteristics of both BIA and SPEs were already recognized forming a robust portable electrochemical system.…”

Electrochemical sensors for malachite green based on carbonaceous nanomaterials

“…A new activated carbon (AC) produced from fir (Abies nordmanniana) cones has been utilized for modification of a glassy carbon electrode in order to obtain a very sensitive and selective sensor for MG. The results were compared with those obtained with other nanomaterials such as single-walled carbon nanotubes (SWCNTs) and reduced graphene oxide (RGO) and with those reported in literature [11][12][13][14].…”

An Overview of Pesticide Monitoring at Environmental Samples Using Carbon Nanotubes-Based Electrochemical Sensors

“…The integration of CNTs in electrochemical sensing applications is very attractive due to their large surface areas [16] and wide useful potential ranges, commonly from −1.0 to +1.0 V [17][18][19] which support various redox reactions [20,21]. Additionally, the superficial incorporation of organic [22,23] and inorganic molecules [24,25], metallic nanoparticles [26], biomolecules [27][28][29], and the nanocomposites of conducting polymers and CNTs [30,31] can increase the field of applications of CNTs in electroanalytical issues.…”