Brief bibliometric analysis of "ionic liquid" applications and its review as a substitute for common adsorbent modifier for the adsorption of organic pollutants

The importance of improving adsorbent's adsorption efficiency in organic pollutants has been reported by many researchers. Surfactant-based modified adsorbents were a tasteful choice. As a result, the use of surfactants as a modifier for removing organic pollutants has shown to play a very big role in enhancing the adsorption efficiency of different materials. Ionic liquids are receiving extensive interest as green multipurpose compounds, primarily as a replacement for traditional chemicals that are used in many chemical processes. This work gives a brief bibliometric analysis of application of ionic liquid from 1930 to 2017, documents were collected from Scopus database and keywords from the abstracts and titles were analyzed using VOSviewer software. Furthermore, the work presents a review of conventionally known surfactants and the recent likelihood of ionic liquids for modifying adsorbents for adsorption of organic pollutants. Over the period of years between 1930 and 2017, 13,144 documents were published on the application of ionic liquids. VOSviewer software further confirms that adsorption is one of the leading areas in applications of ionic liquids. Review also showed that ionic liquid is a good modifier of adsorbents.

Applications of liquid-phase microextraction in the sample preparation of environmental solid samples

Solvent extraction remains one of the fundamental sample preparation techniques in the analysis of environmental solid samples, but organic solvents are toxic and environmentally harmful, therefore one of the possible greening directions is its miniaturization. The present review covers the relevant research from the field of application of microextraction to the sample preparation of environmental solid samples (soil, sediments, sewage sludge, dust etc.) published in the last decade. Several innovative liquid-phase microextraction (LPME) techniques that have emerged recently have also been applied as an aid in sample preparation of these samples: single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid-liquid microextraction (DLLME). Besides the common organic solvents, surfactants and ionic liquids are also used. However, these techniques have to be combined with another technique to release the analytes from the solid sample into an aqueous solution. In the present review, the published methods were categorized into three groups: LPME in combination with a conventional solvent extraction; LPME in combination with an environmentally friendly extraction; LPME without previous extraction. The applicability of these approaches to the sample preparation for the determination of pollutants in solid environmental samples is discussed, with emphasis on their strengths, weak points and environmental impact.

Three-phase hollow fiber liquid-phase microextraction based on two immiscible organic solvents for determination of tramadol in urine and plasma samples

Recently, the new concept of three-phase liquid microextraction was introduced based on applying two immiscible organic solvents in lumen and wall pores of hollow fiber. In the present work, this novel microextraction technique combined with gas chromatography-mass spectrometry has been developed for determination of tramadol, an analgesic agent, in plasma and urine samples. A systematic investigation of the proposed method was applied to find optimal extraction conditions and evaluate the interaction effects between the factors by designing experiments according to the methodology of Box-Behnken response surface design. Analysis of variance (ANOVA) revealed that the important factors contributing to extraction efficiency are extraction time, stirring rate and hollow fiber length. Under the optimum conditions, the developed method provided a preconcentration factor of 546, good repeatability (RSD %=6.4), and good linearity (r(2)=0.995) for spiked plasma and urine real samples. The linear dynamic range from 0.1 to 400 μg L(-1) and limit of detection (LOD) of 0.08 μg L(-1) were obtained under selected ion monitoring mode. The results demonstrated that three-phase hollow fiber microextraction based on two immiscible solvents is a simple and accurate technique with very good preconcentration factor and clean-up for extraction of tramadol from biological samples.