title: Graphene-polyaniline modified electrochemical droplet-based microfluidic sensor for high-throughput determination of 4-aminophenol.
abstract: We report herein the first development of graphene-polyaniline modified carbon paste electrode (G-PANI/CPE) coupled with droplet-based microfluidic sensor for high-throughput detection of 4-aminophenol (4-AP) in pharmaceutical paracetamol (PA) formulations. A simple T-junction microfluidic platform using an oil flow rate of 1.8 μL/min and an aqueous flow rate of 0.8 μL/min was used to produce aqueous testing microdroplets continuously. The microchannel was designed to extend the aqueous droplet to cover all 3 electrodes, allowing for electrochemical measurements in a single droplet. Parameters including flow rate, water fraction, and applied detection potential (Edet) were investigated to obtain optimal conditions. Using G-PANI/CPE significantly increased the current response for both cyclic voltammetric detections of ferri/ferrocyanide [Fe(CN)6](3-/4-) (10 times) and 4-AP (2 times), compared to an unmodified electrode. Using the optimized conditions in the droplet system, 4-AP in the presence of PA was selectively determined. The linear range of 4-AP was 50-500 μM (R(2) = 0.99), limit of detection (LOD, S/N = 3) was 15.68 μM, and limit of quantification (LOQ, S/N = 10) was 52.28 μM. Finally, the system was used to determine 4-AP spiked in commercial PA liquid samples and the amounts of 4-AP were found in good agreement with those obtained from the conventional capillary zone electrophoresis/UV-Visible spectrophotometry (CZE/UV-Vis). The proposed microfluidic device could be employed for a high-throughput screening (at least 60 samples h(-1)) of pharmaceutical purity requiring low sample and reagent consumption.
authors.affiliation: Electrochemistry and Optical Spectroscopy Research Unit (EOSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand.
authors.forename: Poomrat
authors.initials: P
authors.lastname: Rattanarat
authors.affiliation: Electrochemistry and Optical Spectroscopy Research Unit (EOSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand; Chromatography and Separation Research Unit (ChSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand.
authors.forename: Akkapol
authors.initials: A
authors.lastname: Suea-Ngam
authors.affiliation: Program in Macromolecular Science, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand.
authors.forename: Nipapan
authors.initials: N
authors.lastname: Ruecha
authors.affiliation: Department of Chemistry, Faculty of Science, Srinakharinwirot University, Sukhumvit 23, Wattana, Bangkok 10110, Thailand.
authors.forename: Weena
authors.initials: W
authors.lastname: Siangproh
authors.affiliation: Department of Chemistry, Colorado State University, Fort Collins, CO 80523, United States; School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, United States.
authors.forename: Charles S
authors.initials: CS
authors.lastname: Henry
authors.affiliation: Electrochemistry and Optical Spectroscopy Research Unit (EOSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand; Chromatography and Separation Research Unit (ChSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand.
authors.forename: Monpichar
authors.initials: M
authors.lastname: Srisa-Art
authors.affiliation: Electrochemistry and Optical Spectroscopy Research Unit (EOSRU), Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand; National Center of Excellent of Petroleum, Petrochemicals and Advanced Materials, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand. Electronic address: corawon@chula.ac.th.
authors.forename: Orawon
authors.initials: O
authors.lastname: Chailapakul
mesh_terms: D000627:Aminophenols / Q000032:analysis*; D000814:Aniline Compounds / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000379:methods; D006108:Graphite / Q000737:chemistry*; D057166:High-Throughput Screening Assays; D044085:Microfluidics / Q000295:instrumentation*; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission
chemical_list: D000627:Aminophenols; D000814:Aniline Compounds; C416807:polyaniline; D006108:Graphite; C026729:4-aminophenol
keywords: 4-Aminophenol; Droplet-based microfluidics; Electrochemical detection; Graphene; Paracetamol; Polyaniline