Electrochemically controlled solid-phase micro-extraction of proline using a nanostructured film of polypyrrole, and its determination by ion mobility spectrometry

Polypyrrole Nanomaterials: Structure, Preparation and Application

In the past decade, nanostructured polypyrrole (PPy) has been widely studied because of its many specific properties, which have obvious advantages over bulk-structured PPy. This review outlines the main structures, preparation methods, physicochemical properties, potential applications, and future prospects of PPy nanomaterials. The preparation approaches include the soft micellar template method, hard physical template method and templateless method. Due to their excellent electrical conductivity, biocompatibility, environmental stability and reversible redox properties, PPy nanomaterials have potential applications in the fields of energy storage, biomedicine, sensors, adsorption and impurity removal, electromagnetic shielding, and corrosion resistant. Finally, the current difficulties and future opportunities in this research area are discussed.

The effect of different binders on the comprehensive performance of solid phase microextraction fiber

Binders are significant components for the preparation of solid-phase microextraction (SPME) fibers. However, little attention has been paid to the effect of different binders. Considering their diverse properties, in this work, we select three kinds of commonly used binders including polydimethylsiloxane (PDMS), polyacrylonitrile (PAN) and Nafion, as well as introduce a new binder of poly (vinylidene fluoride) (PVDF) to synthetically study the influence of binders. By using the commercial active carbons (ACs) with different binders, four SPME fibers with uniform morphologies and comparative thicknesses (i.e., ACs-PDMS-coated, ACs-PAN-coated, ACs-Nafion-coated and ACs-PVDF-coated fibers) have been prepared successfully. The effect of binders on the pore structure of ACs is firstly investigated. It is found that PDMS and PAN would cause pore blocking, and the specific surface area of ACs coatings decreases from 1362 m² g^-1 to 280 and 196 m² g^-1, respectively. While the specific surface area of ACs-PVDF composite remains 940 m² g^-1. Based on SPME, the influences of acid/alkali, high temperature and matrix towards different fibers are further systematically surveyed. Finally, the enrichment performance of prepared fibers towards various organic pollutants is preliminarily discussed. The comparison results show that PVDF demonstrates outstanding stability in all aspects. Therefore, PVDF might be an excellent candidate for the preparation of SPME fiber. Moreover, all obtained results are expected to provide the reference value for the further development of novel SPME fibers.

Electrochemically Fabricated Solid Phase Microextraction Fibers and Their Applications in Food, Environmental and Clinical Analysis

Background:

Designing an analytical methodology for complicated matrices, such as biological and environmental samples, is difficult since the sample preparation procedure is the most demanding step affecting the whole analytical process. Nowadays, this step has become more challenging by the legislations and environmental concerns since it is a prerequisite to eliminate or minimize the use of hazardous substances in traditional procedures by replacing with green techniques suitable for the sample matrix.

Methods:

In addition to the matrix, the nature of the analyte also influence the ease of creating green analytical techniques. Recent developments in the chemical analysis provide us new methodologies introducing microextraction techniques and among them, solid phase microextraction (SPME) has emerged as a simple, fast, low cost, reliable and portable sample preparation technique that minimizes solvent consumption.

Results:

The use of home-made fibers is popular in the last two decades since the selectivity can be tuned by changing the surface characteristics through chemical and electrochemical modifications. Latter technique is preferred since the electroactive polymers can be coated onto the fiber under controlled electrochemical conditions and the film thicknesses can be adjusted by simply changing the deposition parameters. Thermal resistance and mechanical strength can be readily increased by incorporating different dopant ions into the polymeric structure and selectivity can be tuned by inserting functional groups and nanostructures. A vast number of analytes with wide range of polarities extracted by this means can be determined with a suitable chromatographic detector coupled to the system. Therefore, the main task is to improve the physicochemical properties of the fiber along with the extraction efficiency and selectivity towards the various analytes by adjusting the electrochemical preparation conditions.

Conclusion:

This review covers the fine tuning conditions practiced in electrochemical preparation of SPME fibers and in-tube systems and their applications in environmental, food and clinical analysis.

Evaluation of in-tube solid-phase microextraction method for co-extraction of acidic, basic, and neutral drugs

Simultaneous extraction of acidic, basic, and neutral drugs from different biological samples is a considerable and disputable concept in sample preparation strategies.