Dispersive Liquid-liquid Research Articles

Determination of Trace Cobalt in Water Samples by Ionic Liquid-Dispersive Liquid–Liquid Microextraction and Graphite Furnace Atomic Absorption Spectrometry

Determination of Trace Cobalt in Water Samples by Ionic Liquid-Dispersive Liquid–Liquid Microextraction and Graphite Furnace Atomic Absorption Spectrometry

Ionic Liquid-Dispersive Micro-Extraction and Detection by High Performance Liquid Chromatography-Mass Spectrometry for Antifouling Biocides in Water.

A simple analytical method was developed and evaluated for the determination of two antifouling biocides using an ionic liquid-dispersive liquid-liquid micro-extraction (IL-DLLME) and a high-performance liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) analysis. Irgarol 1051 and Sea-Nine 211 were extracted from deionized water, lake water, and seawater using IL 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIm][PF6]) and ethyl acetate as the extraction solvent and the dispersion solvent. Several factors were considered, including the type and volume of extraction and dispersive solvent, IL amount, sample pH, salt effect, and cooling temperature. The developed method resulted in a recovery range of 78.7-90.3%, with a relative standard deviation (RSD, n = 3) less than 7.5%. The analytes were enriched greater than 40-fold, and the limits of detection (LOD) for two antifouling biocides were 0.01-0.1 μg L-1. The method was effectively applied for the analysis of real samples of freshwater as well as samples of seawater.

Ultrasound-Assisted Ionic Liquid Microextraction for Preconcentration of Cadmium in Water, Vegetables and Hair Samples Prior to FAAS Determination

Background:: Cadmium (Cd2+) is considered to be one of the most important hazardous heavy metals due to its toxicity for living organisms at low concentration levels. Therefore, the estimation of trace Cd2+ in different types of various samples is a very important objective for chemists using effective methods. In the present work, a novel, green, easy and fast ultrasoundassisted ionic liquid-dispersive liquid phase microextraction technique (UA-IL-DLPME) was developed to preconcentrate and determine trace quantities of cadmium (Cd2+) ions from real samples, prior to detection by FAAS. Methods: The proposed technique is based on utilization of ionic liquid (IL) (1-hexyl-3- methylimidazolium tris(pentafluoroethyl)trifluorophosphate [HMIM][FAP]) as an extraction solvent for Cd2+ ions after complexation with 2-(6-methylbenzothiazolylazo)-6-nitrophenol (MBTANP) at pH 7.0. The impact of different analytical parameters on the microextraction efficiency was investigated. The validation of the proposed procedure was verified by the test of two certified reference materials (TMDA-51.3 fortified water, SRM spinach leaves 1570A) applying the standard addition method. Results: In the range of 2.0-200 μg L−1, the calibration graph was linear. Limit of detection, preconcentration factor and the relative standard deviation (RSD %, 100 μg L-1, n=5) as precision was 0.1 μg L-1, 100 and 3.1%, respectively. Conclusion: Green UA-IL-DLPME method was developed and applied to preconcentrate and determine trace quantities of Cd2+ in real water, vegetables and hair samples with satisfactory results.

Ultrasound-Assisted Ionic Liquid-Dispersive Liquid-Liquid of Curcumin in Food Samples Microextraction and Its Spectrophotometric Determination.

Background: A rapid and new ultrasound-assisted ionic liquid-dispersive liquid-liquid microextraction method (UA-IL-DLLME) was presented for the determination of curcumin by spectrophotometry. Objective: To determine trace levels of curcumin in food samples by using green and low-cost method development. Methods: 1-Butyl-3-methylimidazolium hexafluorophosphate was used to extract curcumin from sample solutions with the aid of sonication. Optimum extraction efficiency was determined by examining extraction solvents, pH, centrifugation speed, time, sonication period, and temperature. The influences of diverse ions on the recovery of curcumin were examined. The concentration of curcumin in the final solution was measured by spectrophotometer at 425 nm. Results: The enrichment factor achieved was 167. The LOD and the RSD were 0.51 μg/L and 4.3%, respectively. The presented method was performed to detect curcumin in 20 food samples. Conclusions: The presented UA-IL-DLLME method is simple, low in cost, environmentally friendly, rapid, and sensitive and requires minimal use of toxic organic solvents. Highlights: A microextraction method was applied to increase sensitivity. Higher enrichment factors and lower detection limits were observed. The proposed technique is easy, cost-effective, accurate, and precise.

Recent Trends in Microextraction Techniques Employed in Analytical and Bioanalytical Sample Preparation

Sample preparation has been recognized as a major step in the chemical analysis workflow. As such, substantial efforts have been made in recent years to simplify the overall sample preparation process. Major focusses of these efforts have included miniaturization of the extraction device; minimizing/eliminating toxic and hazardous organic solvent consumption; eliminating sample pre-treatment and post-treatment steps; reducing the sample volume requirement; reducing extraction equilibrium time, maximizing extraction efficiency etc. All these improved attributes are congruent with the Green Analytical Chemistry (GAC) principles. Classical sample preparation techniques such as solid phase extraction (SPE) and liquid-liquid extraction (LLE) are being rapidly replaced with emerging miniaturized and environmentally friendly techniques such as Solid Phase Micro Extraction (SPME), Stir bar Sorptive Extraction (SBSE), Micro Extraction by Packed Sorbent (MEPS), Fabric Phase Sorptive Extraction (FPSE), and Dispersive Liquid-Liquid Micro Extraction (DLLME). In addition to the development of many new generic extraction sorbents in recent years, a large number of molecularly imprinted polymers (MIPs) created using different template molecules have also enriched the large cache of microextraction sorbents. Application of nanoparticles as high-performance extraction sorbents has undoubtedly elevated the extraction efficiency and method sensitivity of modern chromatographic analyses to a new level. Combining magnetic nanoparticles with many microextraction sorbents has opened up new possibilities to extract target analytes from sample matrices containing high volumes of matrix interferents. The aim of the current review is to critically audit the progress of microextraction techniques in recent years, which has indisputably transformed the analytical chemistry practices, from biological and therapeutic drug monitoring to the environmental field; from foods to phyto-pharmaceutical applications.

Quick, Easy, Cheap, Effective, Rugged, and Safe Method Followed by Ionic Liquid-Dispersive Liquid–Liquid Microextraction for the Determination of Trace Amount of Bisphenol A in Canned Foods

Combination of the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method with ionic liquid-dispersive liquid–liquid microextraction (QuEChERS-IL-DLLME) was developed as an extraction methodology to determine bisphenol A (BPA) in various canned food samples prior to high-performance liquid chromatography ultraviolet detection (HPLC-UV). The potential variables affecting the microextraction recovery were considered in the optimization process. Obtained results showed that 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C6mim][Tf2N]) is a better extraction solvent compared with 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6mim][PF6]) and is more compatible with RP-HPLC. Under the optimum conditions, the method yielded a linear calibration curve ranging from 1.0 to 500 μL−1 with a determination coefficient (R2) of 0.9993. Enrichment factor for BPA was 98, and limit of detection was 0.1 μg L−1. The relative standard deviation percent (RSD%) for the intra-day and inter-day extraction and determination at 2.0, 20, and 200 μg L−1 levels of BPA was less than 7.2 % (n = 6) and 9.7 % (n = 6), respectively. Finally, the proposed method was successfully applied for the extraction, cleanup, preconcentration, and determination of the BPA in different canned food samples, and satisfactory results were obtained (relative recovery ≥90 %).

Simultaneous Determination of 13 Priority Polycyclic Aromatic Hydrocarbons in Tehran's Tap Water and Water for Injection Samples Using Dispersive Liquid-Liquid Micro Extraction Method and Gas Chromatography-Mass Spectrometry.

Polycyclic aromatic hydrocarbons (PAHs) are classified as persistent and carcinogenic organic pollutants. PAHs contamination has been reported in water. Many of relevant regulatory bodies such as EU and EPA have regulated the limit levels for PAHs in drinking water. In this study, 13 priority polycyclic aromatic hydrocarbons (PAHs) were determined in tap water samples of Tehran and water for injection. Dispersive liquid-liquid microextraction procedure combined with gas chromatography-mass spectrometry was used for the extraction and determination of PAHs in the samples. Under the optimized conditions, the range of extraction recoveries and relative standard deviations (RSDs) of PAHs in water using internal standard (anthracene-d10) were in the range of 71-90% and 4-16%, respectively. Limit of detection for different PAHs were between 0.03 and 0.1 ngmL(-1). The concentration of PAHs in all tap water as well as water for injection samples were lower than the limit of quantification of PAHs. This is the first study addressing the occurrence of PAHs in water for injection samples in Iran using dispersive liquid-liquid micro extraction procedure combined with gas chromatography-mass spectrometry.

Determination of Cadmium in Rice by Dispersive Liquid-Liquid Micro Extraction-Hydride Generation-Atomic Fluorescence Spectrometry

Determination of Cadmium in Rice by Dispersive Liquid-Liquid Micro Extraction-Hydride Generation-Atomic Fluorescence Spectrometry

Determination of chlorophenols in honey samples using in-situ ionic liquid-dispersive liquid–liquid microextraction as a pretreatment method followed by high-performance liquid chromatography

In-situ ionic liquid-dispersive liquid–liquid microextraction (IL-DLLME) method was developed as a pretreatment method for the detection of six chlorophenols (CPs) in honey samples. The hydrophobic ionic liquid [C4MIM][NTf2], formed in-situ by the hydrophilic ionic liquid [C4MIM][BF4] and the ion exchange reagent LiNTf2 was used as the microextractant solvent of CPs from honey sample. Then the enriched analytes were back-extracted into 40μL of 0.14M NaOH solution and finally subjected to analysis by high-performance liquid chromatography. The method showed low limit of detection of CPs, 0.8–3.2μg/L and high enrichment factor, 34–65 with the recoveries range from 91.60% to 114.33%. The method is simple, rapid, environmentally friendly and with high extraction efficiency.

Ionic Liquid-Magnetic Nanoparticle Microextraction of Safranin T in Food Samples

A new two-step microextraction approach combining ionic liquid-dispersive liquid–liquid microextraction with magnetic-dispersive microsolid-phase extraction was developed for the fluorescence determination of safranin T in food samples. In the first step, ionic liquid (1-hexyl-3-methylimidazolium hexafluorophosphate (C6MIM][PF6)) was used to extract safranin T from a sample solution with the assistance of controlled temperature conditions. Fe3O4@SiO2 magnetic nanoparticles were then used to retrieve the ionic liquid, which were collected by application of an external magnetic field. The ionic liquid and safranin T were recovered from the surface of magnetic nanoparticles using ultrasound and an organic solvent. The effective factors in the proposed method, including type and volume of extraction solvent, pH, dispersive temperature and extraction time, type of desorption solvent, amount of Fe3O4@SiO2 magnetic nanoparticles, and ultrasound time were optimized. Under the optimal conditions (extraction solvent, 100 μL of [C6MIM][PF6]; pH 9.0; dispersive temperature, 80 °C; extraction time, 5 min; desorption solvent, acetone; amount of Fe3O4@SiO2 magnetic nanoparticles, 5 mg; ultrasound time, 120 s), the method presented has good linearity (r 2 = 0.9994) in the range of 5–300 ng mL−1. The detection limit was 0.48 ng mL−1, while the relative standard deviation for the analysis of 100 ng mL−1 of the safranin T was 1.47 % (n = 10). The method was successfully applied to the determination of safranin T in tomatoes, tomato sauce, and yuba samples, and good recovery rates (96.71–98.26 %) with relative standard deviation of below 2 % were achieved.

Room Temperature Ionic Liquid-Based Dispersive Liquid Phase Microextraction for the Separation/Preconcentration of Trace Cd2+ as 1-(2-pyridylazo)-2-naphthol (PAN) Complex from Environmental and Biological Samples and Determined by FAAS

The current work develops a new green methodology for the separation/preconcentration of cadmium ions (Cd(2+)) using room temperature ionic liquid-dispersive liquid phase microextraction (RTIL-DLME) prior to analysis by flame atomic absorption spectrometry with microsample introduction system. Room temperature ionic liquids (RTIL) are considered "Green Solvents" for their thermally stable and non-volatile properties, here 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6] was used as an extractant. The preconcentration of Cd(2+) in different waters and acid digested scalp hair samples were complexed with 1-(2-pyridylazo)-2-naphthol and extracted into the fine drops of RTILs. Some significant factors influencing the extraction efficiency of Cd(2+) and its subsequent determination, including pH, amount of ligand, volume of RTIL, dispersant solvent, sample volume, temperature, and incubation time were investigated in detail. The limit of detection and the enhancement factor under the optimal conditions were 0.05 μg/L and 50, respectively. The relative standard deviation of 100 μg/L Cd(2+) was 4.3 %. The validity of the proposed method was checked by determining Cd(2+) in certified reference material (TM-25.3 fortified water). The sufficient recovery (>98 %) of Cd(2+) with the certified value. The mean concentrations of Cd in lake water 13.2, waste water 15.7 and hair sample 16.8 μg/L, respectively and the developed method was applied satisfactorily to the preconcentration and determination of Cd(2+) in real samples.

Ionic liquid based dispersive liquid–liquid microextraction coupled with micro-solid phase extraction of antidepressant drugs from environmental water samples

Ionic liquid-dispersive liquid–liquid microextraction combined with micro-solid phase extraction (IL-DLLME-μ-SPE), and high-performance liquid chromatography (HPLC) was developed for the determination of tricyclic antidepressants (TCAs) in water samples. Two hundred microliters of an organic solvent (as disperser solvent) and 20μl of 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate were injected into a 5.0ml sample for sonication-assisted DLLME. After this, a μ-SPE device, containing a novel material zeolite imidazolate framework 4 (ZIF-4), was added into the sample solution and 1min of vortex-assisted extraction was performed. After 5min of sonication-assisted desorption, 10μl of desorption solvent was injected into a HPLC system for analysis. A characteristic property of DLLME-VA-μ-SPE is that any organic solvent and solid sorbent immiscible with water can be used. Special apparatus, or conical-bottom test tubes, and tedious procedures conventionally associated with DLLME such as centrifugation, or refrigeration of solvent are not necessary in the present approach. A novel material, ZIF-4 was employed as μ-SPE sorbent. Under the optimized conditions, the calibration curves were linear in the range of 1–1000μg/L. The relative standard deviations and the limits of detection were in the range of 1.5% and 7.8% and 0.3 and 1μg/L, respectively. The relative recoveries of canal water samples, spiked with drugs, were in the range of 94.3% and 114.7%. The results showed that IL-DLLME-μ-SPE was suitable for the determination of TCAs in water samples.

Ultrasound-assisted ionic liquid/ionic liquid-dispersive liquid–liquid microextraction for the determination of sulfonamides in infant formula milk powder using high-performance liquid chromatography

Ultrasound-assisted ionic liquid/ionic liquid-dispersive liquid–liquid microextraction (UA-IL/IL-DLLME) high-performance liquid chromatography was developed and applied to the extraction, separation and determination of sulfonamides in infant formula milk powder samples. The hydrophobic IL and hydrophilic IL were used as extraction solvent and dispersion solvent, respectively. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of [C6MIM][PF6] dispersed entirely into sample solution with help of [C4MIM][BF4]. The purification of sample and concentration of target analytes were performed simultaneously. The introduction of ion-pairing agent (NH4PF6) was beneficial to the improvement of recoveries for IL phase and analytes. The experimental parameters of the UA-IL/IL-DLLME, including concentration of [C6MIM][PF6] and [C4MIM][BF4] in sample solution, ultrasound extraction time, pH value of sample solution and amount of ion-pairing agent (NH4PF6), were evaluated. The limits of detection for sulfamerazine, sulfamethizole, sulfachlorpyridazine, sulfamonomethoxine, sulfmethoxazole and sulfisoxazole were 2.94, 9.26, 16.7, 5.28, 3.35 and 6.66μgkg−1, respectively. When the present method was applied to the analysis of infant formula milk powder samples, the recoveries of the analytes ranged from 90.4% to 114.8% and relative standard deviations were lower than 7.5%. The proposed method was compared with the ionic liquid-homogeneous liquid–liquid microextraction, ionic liquid-ultrasound-assisted emulsification–microextraction and ionic liquid-temperature-controlled-DLLME. The results indicated that the proposed method is effective for the extraction of the sulfonamides in milk powder samples.

Temperature controlled ionic liquid-dispersive liquid phase microextraction for determination of trace lead level in blood samples prior to analysis by flame atomic absorption spectrometry with multivariate optimization

This paper described a new approach for the preconcentration of lead (Pb2+) by temperature controlled ionic liquid-dispersive liquid phase microextraction (TIL-DLME) prior to analyzing by flame atomic absorption spectrometry (FAAS). An ionic liquid (IL) 1-Butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6] was used as an extractant solvent. The Pb2+ was complexed with ammonium pyrrolidinedithiocarbamate (APDC) and then entered into the infinite IL drops at high temperature (>70°C). Important variables affecting the microextraction efficiency such as pH, ligand concentration, amount of IL, temperature and incubation time were investigated. The results showed that the coexistent ions had no obvious negative effect on the determination of Pb2+. In the optimum experimental conditions, the limit of detection (LOD) and the enhancement factor (EF) were 0.13μgL−1 and 93, respectively. The relative standard deviation (RSD) of 10μgL−1 Pb2+ was 4.3%. The developed method was validated by determining Pb2+ in certified reference material (CRM) and the results showed that the determined values of Pb2+ were in good agreement with the certified value. The proposed method was applied satisfactorily for the preconcentration of Pb2+ in acid digested blood samples of children with different respiratory disorders.

Effective indirect enrichment and determination of nitrite ion in water and biological samples using ionic liquid-dispersive liquid–liquid microextraction combined with high-performance liquid chromatography

An ionic liquid dispersive liquid–liquid microextraction high-performance liquid chromatography (IL-DLLME-HPLC) method for effective enrichment and determination of nitrite ion in water and biological samples was developed. The method was based on the reaction of nitrite ion with p-nitroaniline in the presence of diphenylamine in acid media and IL-DLLME of azo product. The optimization of reaction and extraction conditions, such as kind and concentration of acid, reaction time, volume of reaction solvent, temperature, kind of extraction and dispersive solvent, volume of extraction and dispersive solvent, addition of salt, extraction and centrifugal time were studied. Under the optimal conditions, 1-octyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide IL-DLLME procedure provided high enrichment factor of 430 and good extraction recovery of 91.7% for nitrite ion. The linearity was observed in the range of 0.4–500.0 μg L −1 with good correlation coefficient ( r 2 = 0.9996). The relative standard deviations (RSDs) for five replicate measurements varied between 1.5% and 4.8%. The limit of detection of the method (S/N = 3) was 0.05 μg L −1. The interference effect of some anions and cations was also tested. The developed method allowed achieving an excellent enrichment factor, yielding a lower LOD in comparison with other methods. Moreover, the proposed method was able to analyze nitrite ion in water and biological samples with satisfactory recovery ranged from 96.5% to 107.3%.

Ionic liquid-dispersive liquid–liquid microextraction for the simultaneous determination of pesticides and metabolites in soils using high-performance liquid chromatography and fluorescence detection

In this work, an ionic liquid-dispersive liquid–liquid microextraction (IL-DLLME) procedure was developed for the extraction of a group of pesticides (carbendazim/benomyl, thiabendazole, fuberidazole, carbaryl and triazophos) and some of their key metabolites in soils (2-aminobenzimidazole, metabolite of carbendazim and 1-naphthol, metabolite of carbaryl) from aqueous soil extracts, using high performance liquid chromatography (HPLC) with fluorescence detection (FD). Analytes were previously extracted from four soils with different physicochemical properties (forestal, ornamental, garden and lapilli soils) by ultrasound-assisted extraction (USE). The IL 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIm][PF 6]) and methanol (MeOH) were used as extraction and dispersion solvent, respectively, for the DLLME procedure. Factors affecting IL-DLLME (sample pH, IL amount, volume of dispersion solvent and sodium chloride percentage) were optimized by means of an experimental design, obtaining the most favorable results when using 117.5 mg of IL and 418 μL of MeOH to extract the compounds from the aqueous soil extracts at pH 5.20 containing 30% (w/v) NaCl. Calibration of the USE–IL-DLLME–HPLC–FD method was carried out for every type of soil and accuracy and precision studies were developed at two levels of concentration, finding that no significant differences existed between real and spiked concentrations (Student's t test). LODs achieved were in the low ng/g range.