Ionic liquid for high temperature headspace liquid-phase microextraction of chlorinated anilines in environmental water samples

Application of gas flow headspace liquid phase micro extraction coupled with gas chromatography-mass spectrometry for determination of 4-methylimidazole in food samples employing experimental design optimization

Background

4-Methylimidazole (4-MeI) or 4-methyl-1H-imidazole, a slightly yellowish solid with molecular formula C₄H₆N₂, is a heterocyclic compound which supposedly does not exist as a natural product and is formed when carbohydrates are heating with ammonium compounds. This compound is used in pharmaceuticals, agriculture and photography chemicals, dyes and pigments, and rubber manufacturing. In the present study, a simple and efficient sample preparation method designated gas flow headspace liquid phase microextraction (GF-HS-SDME) was employed for the extraction and preconcentration of 4-methylimidazole (4-MeI) from food and beverage samples, before its determination by gas chromatography-mass spectrometry.

Result

To investigate the optimal conditions for the extraction process in GF-HS-SDME method, factors affecting extraction, including selection of extraction solvent, vial volume, extraction solvent ratio, position of extracting solvent, drop volume, sample volume, stirring speed, temperature, extraction time, sample pH, ionic strength of the sample solution and gas flow rate were optimized by utilizing both one-variable-at-a-time method and Plackett–Burman design. The investigation of protocol was carried out by using a standard solution containing 100.0 μg L⁻¹ of 4-MeI in deionized water.

Conclusion

In this study, a simple and green analytical method based on GF-HS-SDME was proposed for the extraction and preconcentration of 4-MeI from foodstuffs, followed by GC–MS determination. The main advantage of this method is its high preconcentration factor and fastness due to the application of an inert gas stream during microextraction.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13065-022-00823-z.

Room-temperature-ionic-liquid coated graphitized carbons for selective preconcentration of polar vapors

Most adsorbent materials used for preconcentrating and thermally desorbing volatile and semi-volatile organic compounds (S/VOCs) in portable or "micro" gas chromatographic (GC/µGC) instruments preferentially capture non-polar or moderately polar compounds relative to more polar compounds. Here, we explore the use of a known trigonal-tripyramidal room-temperature ionic liquid (RTIL) as a surface modifier for the graphitized carbons, Carbopack B (C-B) and Carbopack X (C-X), with the goal of enhancing their capacity and selectivity for polar S/VOCs. Breakthrough tests were performed by challenging tubes packed with ∼2.5 mg of C-B or RTIL-coated C-B (RTIL/C-B) with 13 individual S/VOCs, including several organophosphorus compounds and reference alkyl and aromatic hydrocarbons of comparable vapor pressures, at concentrations ranging from 14 to 130 mg/m³. The 10% breakthrough volume, V_b10, was used as the measure of capacity. For the RTIL/C-B, the V_b10 values of the five organophosphorus vapors tested were consistently ∼2.5 times larger than those for the untreated C-B, and V_b10 values of the four non-polar reference vapors were 11-26 times smaller for the RTIL/C-B than for the untreated C-B. For compounds of similar vapor pressure the capacity ratios for polar vs. non-polar compounds with the RTIL/C-B ranged from 1.8 to 34. Similar results were obtained with C-X and RTIL/C-X on a smaller set of compounds. Tests at 70% relative humidity or with a binary mixture of a polar and non-polar compound had no effect on the capacity of the RTIL/C-B, and there were no changes in V_b10 values after several months of testing that included cycling from 25 to 250 °C. Capacity was strongly correlated with vapor pressure. Attempts to reconcile the selectivity using models based on linear-solvation-energy relationships were only partially successful. Nonetheless, these results indicate that RTIL coating of carbon adsorbents affords a simple, reliable means of rendering them selective for polar S/VOCs.

Ionic liquid based microextraction of targeted lipids from serum using UPLC-MS/MS with a chemometric approach: a pilot study

An ionic liquid based vortex assisted surfactant-enhanced emulsification microextraction method followed by using liquid chromatography-electrospray mass spectrometry have been used for the determination of fatty acids, triglycerides and phospholipids in serum samples.

Recent advances of ionic liquids and polymeric ionic liquids in capillary electrophoresis and capillary electrochromatography

Ionic liquids (ILs) and polymeric ionic liquids (PILs) with unique and fascinating properties have drawn considerable interest for their use in separation science, especially in chromatographic techniques. In this article, significant contributions of ILs and PILs in the improvement of capillary electrophoresis and capillary electrochromatography are described, and a specific overview of the most relevant examples of their applications in the last five years is also given. Accordingly, some general conclusions and future perspectives in these areas are discussed.

Periodic mesoporous organosilica with ionic liquid framework as a novel fiber coating for headspace solid-phase microextraction of polycyclic aromatic hydrocarbons

Periodic mesoporous organosilica based on alkylimidazolium ionic liquid (PMO-IL) was prepared and used as a highly porous fiber coating material for solid-phase microextraction (SPME). The prepared nanomaterial was immobilized onto a stainless steel wire for fabrication of the SPME fiber. The fiber was evaluated for the extraction of some polycyclic aromatic hydrocarbons (PAHs) from aqueous sample solutions in combination with gas chromatography-mass spectrometry (GC-MS). A one at-the-time optimization strategy was applied for optimizing the important extraction parameters such as extraction temperature, extraction time, ionic strength, stirring rate, and desorption temperature and time. In optimum conditions, the repeatability for one fiber (n=3), expressed as relative standard deviation (R.S.D.%), was between 4.3% and 9.7% for the test compounds. The detection limits for the studied compounds were between 4 and 9 pg mL(-1). The developed method offers the advantage of being simple to use, with shorter analysis time, lower cost of equipment, thermal stability of fiber and high relative recovery in comparison to conventional methods of analysis.

Ionic liquids in microextraction techniques

The tremendous potential of room temperature ionic liquids as an alternative to environmentally harmful ordinary organic solvents is well recognized. Due to their unique properties, such as low volatility, tunable viscosity and miscibility, and electrolytic conductivity, ionic liquids have attracted extensive attention and gained popularity in many areas of analytical chemistry including modern sample preparation techniques. In this review the advantages and limitations of application of ionic liquids as solvents/sorbents for microextraction are critically discussed. Topics covered include solid-phase microextraction, single drop microextraction, dispersive liquid-liquid microextraction and hollow-fiber liquid-phase microextraction. The compatibility of the ionic liquid-based microextraction with different analytical techniques such as gas chromatography, high-performance liquid chromatography, electrothermal or flame atomic absorption spectrometry and some others is also discussed. Finally, the main practical applications on this topic are summarized.

Hollow fiber supported liquid-phase microextraction using ionic liquid as extractant for preconcentration of benzene, toluene, ethylbenzene and xylenes from water sample with gas chromatography-hydrogen flame ionization detection

A novel method has been developed for the analysis of benzene, toluene, ethyl-benzene, and o-, m- and p-xylenes (BTEXs) in water using hollow fiber supported liquid-phase microextraction (HF-LPME) followed by gas chromatography-hydrogen flame ionization detection. Ionic liquid 1-butyl-3-methy-limidazolium hexafluorophosphate ([BMIM][PF(6)]) was acted as the extractant for extraction and preconcentration of BTEXs from aqueous samples, and a porous-walled polypropylene hollow fiber was utilized to stabilize and protect [BMIM][PF(6)] during the extraction process. Various parameters that affect extraction efficiency were investigated in detail, and the optimized experimental conditions were as follows: 8 μL of [BMIM][PF(6)] as extraction solvent for the target analytes in 20 mL of sample solution, 30 min of extraction time, a stirring rate of 1400 rpm and 15% NaCl (w/v) in aqueous sample at 25°C (ambient temperature). The recovery was found to be 90.0-111.5% with RSD (n=5) of 1.3-5.4%, and the detection limits (S/N=3) were in the range of 2.7-4.0 μg/L. The proposed method was simple, cheap, rapid, sensitive and environmentally benign, and could act as an alternative to techniques for BTEXs analysis with expensive instrumentations.

Ionic liquid-based homogeneous liquid-liquid microextraction for the determination of antibiotics in milk by high-performance liquid chromatography

Ionic liquid-based homogeneous liquid-liquid microextraction (IL-based HLLME) high-performance liquid chromatography was developed and applied to the extraction, separation and determination of some antibiotics in milk. The proteins and lipids were removed by adding salt and adjusting the pH value. The homogeneous extraction was applied to the improvement of recoveries for IL phase and analytes. The experimental parameters of the IL-based HLLME, including salt concentration in sample solution, pH value of sample solution, volume of [C(6)MIM][BF(4)], amount of ion-pairing agent (NH(4)PF(6)), and extraction time, were evaluated. The limits of detection for enoxacin, pefloxacin, norfloxacin, enrofloxacin, sulfamethoxazole and sulfadimethoxine were 15.8, 7.07, 5.13, 4.00, 7.79 and 8.33 μg L(-1), respectively. When the proposed method was applied to the analysis of milk samples the recoveries of the analytes ranged from 92.5 to 118.6% and relative standard deviations were lower than 7.00%.

Degradation of dichloroaniline isomers by a newly isolated strain, Bacillus megaterium IMT21

An efficient 3,4-dichloroaniline (3,4-DCA)-mineralizing bacterium has been isolated from enrichment cultures originating from a soil sample with a history of repeated exposure to diuron, a major metabolite of which is 3,4-DCA. This bacterium, Bacillus megaterium IMT21, also mineralized 2,3-, 2,4-, 2,5- and 3,5-DCA as sole sources of carbon and energy. These five DCA isomers were degraded via two different routes. 2,3-, 2,4- and 2,5-DCA were degraded via previously unknown dichloroaminophenol metabolites, whereas 3,4- and 3,5-DCA were degraded via dichloroacetanilide.

Recent applications of ionic liquids in separation technology

Ionic liquids (ILs) have been applied in different areas of separation, such as ionic liquid supported membranes, as mobile phase additives and surface-bonded stationary phases in chromatography separations and as the extraction solvent in sample preparations, because they can be composed from various cations and anions that change the properties and phase behavior of liquids. Although the applications of ILs in separations are still in their early stages, the academic interest in ILs is increasing. An overview of the principle applications of ILs in separation technology is present in this work. Furthermore, the prospects of the ILs in separation techniques are discussed.