Polyaniline immobilized on polycaprolactam nanofibers as a sorbent in electrochemically controlled solid-phase microextraction coupled with HPLC for the determination of angiotensin II receptor antagonists in human blood plasma

A Hybrid Stainless-Steel SPME Microneedle Electrode Sensor for Dual Electrochemical and GC-MS Analysis

A mechanically robust in-tube stainless steel microneedle solid phase microextraction (SPME) platform for dual electrochemical and chromatographic detection has been demonstrated. The SPME microneedle was fabricated by layer-by-layer (LbL) in-tube coating, consisting of carbon nanotube (CNT)/cellulose nanocrystal (CNC) film layered with an electrically conductive polyaniline (PANI) hydrogel layer (PANI@CNT/CNC SPME microneedle (MN)). The PANI@CNT/CNC SPME MN showed effective analysis of caffeine by GC-MS with an LOD of 26 mg/L and excellent precision across the dynamic range. Additionally, the PANI@CNT/CNC SPME MN demonstrated a 67% increase in sensitivity compared to a commercial SPME fiber, while being highly robust for repeated use without loss in performance. For electrochemical detection, the PANI@CNT/CNC SPME MN showed excellent performance for the detection of 3-caffeoylquinic acid (3-CQA). The dynamic range and limits of detection (LOD) for 3-CQA analysis were 75-448 mg/L and 11 mg/L, respectively. The PANI@CNT/CNC SPME MN was demonstrated to accurately determine the caffeine content and 3-CQA in tea samples and dark roast coffee, respectively. The PANI@CNT/CNC SPME MN was used for semiquantitative antioxidant determination and composition analysis in kiwi fruit using electrochemistry and SPME-coupled GC-MS, respectively.

Polyaniline and Polyaniline-Based Materials as Sorbents in Solid-Phase Extraction Techniques

Polyaniline (PANI) is one of the best known and widely studied conducting polymers with multiple applications and unique physicochemical properties. Due to its porous structure and relatively high surface area as well as the affinity toward many analytes related to the ability to establish different types of interactions, PANI has a great potential as a sorbent in sample pretreatment before instrumental analyses. This study provides an overview of the applications of polyaniline and polyaniline composites as sorbents in sample preparation techniques based on solid-phase extraction, including conventional solid-phase extraction (SPE) and its modifications, solid-phase microextraction (SPME), dispersive solid-phase extraction (dSPE), magnetic solid-phase extraction (MSPE) and stir-bar sorptive extraction (SBSE). The utility of PANI-based sorbents in chromatography was also summarized. It has been shown that polyaniline is willingly combined with other components and PANI-based materials may be formed in a variety of shapes. Polyaniline alone and PANI-based composites were successfully applied for sample preparation before determination of various analytes, both metal ions and organic compounds, in different matrices such as environmental samples, food, human plasma, urine, and blood.

Electrospun Conducting Polymers: Approaches and Applications

Inherently conductive polymers (CPs) can generally be switched between two or more stable oxidation states, giving rise to changes in properties including conductivity, color, and volume. The ability to prepare CP nanofibers could lead to applications including water purification, sensors, separations, nerve regeneration, wound healing, wearable electronic devices, and flexible energy storage. Electrospinning is a relatively inexpensive, simple process that is used to produce polymer nanofibers from solution. The nanofibers have many desirable qualities including high surface area per unit mass, high porosity, and low weight. Unfortunately, the low molecular weight and rigid rod nature of most CPs cannot yield enough chain entanglement for electrospinning, instead yielding polymer nanoparticles via an electrospraying process. Common workarounds include co-extruding with an insulating carrier polymer, coaxial electrospinning, and coating insulating electrospun polymer nanofibers with CPs. This review explores the benefits and drawbacks of these methods, as well as the use of these materials in sensing, biomedical, electronic, separation, purification, and energy conversion and storage applications.

Solution blow spinning polysulfone-Aliquat 336 nanofibers: synthesis, characterization, and application for the extraction and preconcentration of losartan from aqueous solutions

Nanofibers are materials used in a wide range of applications due to their unique physicochemical properties. As an alternative to the most common method of its manufacturing (electrospinning) blow spinning has been used since it has greater production efficiency and simplicity. A wide variety of polymers is used for its preparation and can be modified to improve the interaction and selectivity toward specific analytes. Thereby nanofibers have been used for the extraction or removal of organic compounds such as drugs but there are still few reports of drug extractions like losartan. In this work polysulfone-Aliquat 336 nanofibers were prepared using the blow spinning method to extract and preconcentrate losartan. The studies showed that Aliquat 336 incorporation significantly improve the extraction of losartan with polysulfone fibers. Adsorption process was thermodynamically favorable with an adsorption capacity of 15.45 mg·g−1. Thus, it was possible to extract more than 92% of initial losartan using 10 mg of polysulfone-Aliquat 336 fibers (9 and 3.5% (w/v)), at pH 6 from deionized water and synthetic wastewater. Finally, losartan preconcentration was evaluated to facilitate its quantification using ultraviolet–visible spectrometry (UV-Vis), which allowed the determination of this drug at concentrations below the detection limit.

Electrochemically controlled solid phase microextraction based on a conductive polyaniline-graphene oxide nanocomposite for extraction of tetracyclines in milk and water

BACKGROUND

Tetracycline antibiotics are employed for human and animal health and for speeding up growth rates. However, their presence in food products and environmental waters has been a concern for some years. Therefore, a variety of sample preparation methods have been developed for the analysis of tetracycline residues in these matrices.

RESULTS

An electrochemically controlled solid phase microextraction based on a modified copper electrode with polyaniline/graphene oxide (PANI/GO) conductive nanocomposite was developed for the extraction of oxytetracycline, tetracycline and doxycycline before high-performance liquid chromatography-UV analysis. PANI/GO was synthesized by in situ chemical oxidative polymerization, characterized by scanning electron microscopy and Fourier-transform infrared spectroscopy, and bound on the electrode using high purity conductive double-sided adhesive carbon glue. The significant factors affecting the performance of microextraction were investigated and optimized. Under the optimized conditions [sample, 15 mL; sorbent, 10 mg; pH, 3.0; electroextraction voltage, -0.9 V; electroextraction time, 20 min; eluent (MeOH/NH₃ ), 500 μL; and desorption time, 5 min], the limits of detection for target analytes were in the ranges 0.32-1.01 and 2.42-7.59 μg L^-1 in water and milk samples, respectively. The linear ranges were 1.06-750 μg L^-1 for water and 8.05-750 μg L^-1 for milk samples. The intra-day and inter-day precisions were 2.32-3.80 and 3.29-4.25, respectively. The method was applied to the determination of analytes in milk and water samples with different fat contents, and the recoveries were obtained in the range 71-104%.

CONCLUSION

The developed electro-microextraction method provides a facile, rapid, cost-effective, sensitive and efficient promising procedure for the extraction of antibiotics in complex matrices. © 2020 Society of Chemical Industry.