Liquid Microextraction Research Articles

Determination of selected pesticides by GC-FID after CNO/MOF nanocomposites-based dispersive solid phase extraction coupled with liquid microextraction

A nanocomposite based on carbon nano onion and ZIF67 metal-organic framework has been synthesized and was characterized by X-ray diffraction spectroscopy, scanning electron microscopy, and Furrier-transformed infrared spectroscopy. The extraction performance of organochlorine and organophosphorus pesticides by the synthesized nanocomposite was evaluated. The prepared sorbent was used as a sorbent in the dispersive solid-phase extraction method, and then dispersive liquid-liquid microextraction was contacted for more cleanup and preconcentration. The final extracted analytes were analyzed by gas chromatography. In this combined method, the analytes were extracted with only 10 mg of sorbent and 20 μL of tetrachloride carbon as extraction solvent. The affecting parameters on the extraction efficiency were thoroughly investigated by one parameter at a time approach. The precision of the method was measured through intra-day and inter-day (n = 5) repetitive experiments that showed RSD values lower than 6.9 %. The combination of the optimized dispersive solid-phase extraction with dispersive liquid-liquid microextraction followed by gas chromatography provided a powerful procedure for pesticide analysis.

Determination of Pesticides after CNO/MOF Nanocomposites-Based Dispersive Solid Phase Extraction Coupled with Liquid Microextraction Followed by GC Analysis

Determination of Pesticides after CNO/MOF Nanocomposites-Based Dispersive Solid Phase Extraction Coupled with Liquid Microextraction Followed by GC Analysis

Relation between solubility and microextraction recovery data of lamotrigine for prediction of partitioning properties

The aim of this investigation was to study the solubility behavior of lamotrigine (LTG) as a model for basic drugs in the components of solvent systems used for a binary solvent dispersive liquid- liquid microextraction (BS-DLLME). In this system, chloroform (CLF) and dichloromethane (DCM) were used as the binary extracting agents and acetonitrile (ACN) and acetone (ACTN) were used as disperser solvents. Solubility of LTG were measured in the binary mixed solvents of ACN + water, ACTN + water and dry and water saturated mixtures of DCM + CLF at 298.2 K. Furthermore, two solvent mixtures including CLF, DCM, ACN and CLF, DCM, ACTN in various percentages were used to investigate the best solvents composition for extraction of LTG from aqueous samples. The solubility and recovery results were mathematically correlated by the Jouyban-Acree model and the accuracies of this model were evaluated by computing MRD%. The overall MRD% of 7.6% obtained for solubility data and 2.1% for recovery data show the capability of the Jouyban-Acree model for numerical representation of solubility and recovery profiles. Finally, it was tried to find a relation between solubility and recovery data to predict the partitioning of a drug between different liquids and exploring the appropriate solvent system for extraction from aqueous samples via DLLME procedure.

Determination of Trace Nickel after Complexation with a Schiff Base by Switchable Solvent – Liquid Phase Microextraction (SS-LPME) and Flame Atomic Absorption Spectrometry (FAAS)

The determination of trace metals is very crucial in order to identify their functionalities in the human body and help to protect human health. For this purpose, a sensitive and accurate analytical method was developed to determine nickel at trace levels by flame atomic absorption spectrometry after preconcentration with switchable solvent based liquid phase microextraction. Experimental conditions of the method were systematically optimized to maximize the extraction yield. Nickel was complexed with a Schiff base ligand synthesized from the reaction of 1- naphthylamine and 5-bromosalicylaldehyde to obtain an insoluble and easy to extract compound. Under the optimal conditions of the developed system, analytical figures of merit were determined. The relative standard deviation for the lowest concentration in the dynamic working range was under 11% which demonstrated good precision. The enhancement in detection power recorded by the switchable solvent based liquid phase microextraction-flame atomic absorption spectrophotometry compared the conventional flame atomic absorption on the basis of detection limit was approximately 40-fold. The applicability and accuracy of the developed method were investigated by spiking tap water with nickel and the recoveries were from 91 to 98%.

Determination of Palladium in Precious Metal Waste by Sieve Conducted Two Syringes Pressurized Liquid Phase Microextraction (SCTS-PLPME) and Slotted Quartz Tube Flame Atomic Absorption Spectrometry (SQT-FAAS)

Determination of palladium at trace levels in environmental samples is essential due to its harmful properties and threats to living organisms. Hence, a simple but efficient liquid-phase microextraction method is reported by sieve conducted two syringes pressurized liquid phase microextraction (SCTS-PLPME) and slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS). The originality of this system is based on the elimination of disperser solvents that are used to increase the surface area of extractant. The high pressure created by the movement of syringe plungers results in efficient dispersion of the extractants in the sample solution. Parameters that affect the overall efficiency of the extraction method were carefully optimized. The limit of detection (LOD) and quantification (LOQ) under the optimum conditions were 6.0 and 20.0 μg L−1, respectively. The developed method showed good linearity between 20 and 1000 μg L−1, and provided a 25-fold enhancement in detection power compared to conventional FAAS. The optimized method was successfully used to determine the analyte in precious metal waste samples.

A new liquid phase microextraction method-based reverse micelle for analysis of dexketoprofen in human plasma by HPLC-DAD

A new liquid phase microextraction method was developed by used reverse micelle-based coacervates as microextraction agents for the separation of dexketoprofen (DKT) from human plasma before its determination by high-performance liquid chromatography with photodiode-array detection (HPLC-DAD). The change in the concentration of dexketoprofen in the plasma of the male and female patients was successfully monitored by using this method. The proposed method involves the use of reverse micelles of decanoic acid (DA) are dispersed in tetrahydrofuran (THF) and aqueous system. After addition of the DA and THF to the aqueous sample phase, the formation of micelles of nano and molecular size was observed in an ultrasonic bath. The solution was centrifuged, and the DKT extracted into the DA phase was analyzed by HPLC-DAD. Some analytical parameters that important in the developed procedure were examined in detail. The limit of detection (LOD), the limit of quantification (LOQ), the intraday, and inter day relative standard deviation (RSD, %) of the developed method in the plasma sample were found to be 12.8 ng mL−1, 38.8 ng mL−1, 1.7 and 3.9%, respectively. Additional/recovery studies were performed in plasma samples with proposed method, and quantitative recoveries were obtained in the range of 97–100%. The developed microextraction method was applied to human plasma that taken from volunteer patients for the determination of DKT.Graphical abstract

Biocompatible SPME fibers for direct monitoring of nicotine and its metabolites at ultra trace concentration in rabbit plasma following the application of smoking cessation formulations.

The ultra-trace determination of nicotine and its 4 major metabolites (cotinine, nornicotine, norcotinine and anabasine) from rabbit plasma was achieved by a newly developed solid phase microextraction-liquid chromatography-tandem mass spectrometry method. Extraction of the target analytes was performed with hydrophilic/lipophilic balance-polyacrylonitrile SPME fibers. Dual fiber extraction was necessary to guarantee improved recovery at parts-per-trillion levels. Liquid chromatographic analysis was achieved in a 6-min run using a C18 (1.9µm C18, 50mm x 2.1mm) column with a mobile phase flow rate of 0.4mL/min. Tandem mass spectrometry was used for detection and quantification in positive electrospray ionization (ESI+) mode for all the targeted analytes. Two stable isotope-labeled internal standards were used for signal correction and accurate quantification. The mass spectrometer with laminar flow ion flux transport, guaranteed improved signal stability, minimal contamination of the ion guide and reproducibility into the first quadrupole analyzer. The method was validated in line with the Food and Drug Administration (FDA) guidelines for bioanalytical method validation. The results met the acceptance criteria as proposed by the FDA: accuracy was tested at 0.35, 10 and 75µg L-1 and ranged between 98.3-112.2% for nicotine, 94.1-101.9% for cotinine, 94.7-107.0% for nornicotine, 81.1-107.2% for norcotinine and 94.3-115.2% for anabasine, with precision up to 14.2%. Stability tests indicated that all the targeted analytes were stable in the desorption solution for at least 1 week. LOQs ranged from 0.05 to 1µg L-1. The method was successfully applied to analyze plasma samples obtained from rabbits following transdermal application of a smoking cessation formulation loaded with solid lipid nanoparticles containing a nicotine-stearic acid conjugate.

Application of dispersive liquid-liquid micro extraction combined with spectrophotometric technique for preconcentration and determination of cadmium using new organic reagent

A new organic reagent namely 5-(4- isopropoxy-6-(methyl amino)-5- nitrosopyrimidine-2-yl) diazenyl) quinolin-8-ol (IMNDQ) was synthesized, characterized and employed for the estimation of Cadmium (II) afterwards preconcentration using Dispersive liquid- liquid microextraction (DLLME). In this precocentration method, chloroform and methnol were used as extraction and disperser solvents respectively and the ligand 5-(4- isopropoxy-6-(methyl amino)-5- nitrosopyrimidine-2-yl) diazenyl) quinolin-8-ol was used as a reagent for the extraction of Cd (II), Visible spectrophotometry was used for the estimation of the analyte after preconcentration. The influence of various factors on the extraction was investigated, for example disperser and extraction solvent type, pH and concentration of chelating agent. At optimum condition, the enrichment factors of (95) was gotten, the calibration graph was linear in the range (20–100) ng. mL−1 Cd+2 with detection limit of (4.46) ng. mL−1 and relative standard deviation (RSD) for seven duplicate measurements of 60 ng. mL−1 of Cd+2 was (1.12)%.The method was used to the estimation of Cd+2 in some food samples.

Dispersive liquid-liquid microextraction of parabens from pharmaceuticals andpersonal care products prior to their determination using HPLC-DAD

Dispersive liquid--liquid microextraction followed by a back-extraction step was combined with HPLC-DAD for the determination of four parabens (i.e. methyl-, ethyl-, propyl-, and butylparaben). Optimum extraction conditions were found as follows: 225 $\mu $L of chloroform, 0.75 mL of ethanol, 7.5 mL of aqueous solution and within an extraction time of 15 s. Back-extraction into 100 $\mu $L of 50 mM sodium hydroxide solution within 20 s resulted in a reversed-phase HPLC-compatible extract. The analytes were separated at 20 $^{\circ}$C using methanol (A) and water (B), 40:60 (A:B, v/v) as the mobile phase, a flow rate of 1.0 mL min$^{-1}$ and an injection volume of 20 $\mu $L. DAD was set at 258 nm to monitor the analytes. Limits of detection and quantitation were as low as 0.1 and 0.3 $\mu $g mL$^{-1}$, respectively. Coefficients of determination (R$^{2})$ were higher than 0.9950 and percentage relative recoveries were found in the range of 86.5-114.5% for the four parabens from pharmaceuticals and personal care products.

Combination of ultrasonic-assisted dispersive liquid phase micro-extraction with magnetic dispersive solid-phase extraction for the pre-concentration of trace amounts of atrazine in various water samples

ABSTRACT Herein, ultrasonic-assisted liquid phase micro-extraction in tandem with dispersive µ-solid-phase extraction was utilised for the determination of atrazine at µg L−1 concentration levels. Initially, a liquid phase micro-extraction based on dispersion of organic solvent was used for the rapid extraction of atrazine from aqueous solution followed by the extraction organic solvent effectively collected from the solution by using C-18-magnetic nanoparticles without any requirement to centrifugation step. After the elution of the extracted targets from the magnetic nanoparticles, atrazine concentration was monitored by high-performance liquid chromatography with Ultraviolet detector at µg L−1 level. The influencial parameters in the pre-concentration step were as follows: pH of solution, magnetic-based sorbent amount (mg) and 1-octanol volume (µL). Additionally, the selected data for the factors produced by the Box-Behnken design were: pH of sample: 9.0, sorbent amount: 22 mg and the extraction solvent volume: 36 µL. Relative standard deviations under the optimised conditions by the hybrid mentioned extraction method was determined to be <7% and the method detection limit for atrazine was calculated to be 0.3 µg L−1. Limit of quantification was calculated to be 0.8 µg/L for the studied analyte.

Accurate and Precise Determination of Gold in Plating Bath Solution: Deep Eutectic Solvent Based Liquid Phase Microextraction – Slotted Quartz Tube – Flame Atomic Absorption Spectrometry

A sensitive, simple and green deep eutectic solvent based liquid phase microextraction (DES-LPME) method is described for the quantification of trace gold by flame atomic absorption spectrometry with a slotted quartz tube (SQT-FAAS). A 1:2 choline chloride:phenol mixture was utilized as the DES for the extraction of gold from the aqueous solution. All of the parameters affecting the extraction efficiency were optimized to increase the detection power of the FAAS. Under the optimum conditions, the presented method provided a linear range between 15 and 400 µg/L with limits of detection and quantification of 5.1 and 16.9 µg/L, respectively. An approximate 58-fold improvement was obtained in the detection power of the FAAS based on the limit of detection using the optimized DES-LPME-SQT-FAAS method. In order to check the validity/applicability of the method, recovery measurements were performed for spiked gold plating bath samples and the resulting recoveries were between 105.3% and 107.6%. The presented method was employed for real sample analysis.

High-Throughput Solid-Phase Microextraction-Liquid Chromatography-Mass Spectrometry for Microbial Untargeted Metabolomics.

Nowadays, metabolomics data, when combined with other "omics" data, can provide important information regarding systems biology. Acquiring a comprehensive untargeted metabolome snapshot of complex sample matrices requires proper sample preparation, and access to sophisticated analytical instrumentation such as mass spectrometry. In metabolomics, sample preparation has substantial influence on the quality of the obtained metabolome profile. To achieve a real snapshot of the metabolome, the analysis method must be capable of inhibiting metabolite interconversion by immediately quenching all metabolome activity. Application of solid-phase microextraction (SPME), particularly in its in vivo set up, when undertaken in conjunction with a conscious selection of coating type based on the chosen sample matrix and the physicochemical properties of the analytes under study, is capable of providing extraction of representative metabolomes for many biological matrices. Metabolomes identified by SPME include low-abundance species and short-lived or unstable metabolites hardly captured by traditional extraction techniques. SPME coupled to liquid chromatography-high-resolution mass spectrometry has recently been introduced as an innovative alternative technique that integrates sampling, sample preparation, and extraction for metabolic profiling and isolation of candidate biomarkers. This chapter presents a detailed protocol for microbial metabolome analysis of Escherichia coli as a model organism, applying the high-throughput SPME-LC-MS workflow.

Solvent bar micro-extraction for greener application of task specific ionic liquids in multi-elemental extraction

The use of ionic liquids for micro-extraction of metals has been popularized during the last decades. The main drawback for this application of ILs is leaching into the sample. Hollow fiber liquid phase micro-extraction might be a promising approach due to the immobilization of the ILs during the extraction process.Herein, we evaluate the abilities of Aliquat® 336 and its thiosalicylate ([A336][TS]) and 2-(methylthio)benzoate ([A336][MTBA]) derivatives, as well as Cyphos® IL 101 salicylate ([C101][Sal]) and anthranilate ([C101][Ant]) analogs supported on a solvent micro-extraction bar to extract metallic ions such as Ag(I), Cd(II), Cr(VI), Cu(II), Ni(II), Pb(II) and Pt(VI) from aqueous solutions. Leaching was reduced by ca. 60% using SBME compared to liquid-liquid extraction for most of the ionic liquids tested; an 88% reduction was achieved using Aliquat® 336.Regarding metal extraction, quantitative removal was obtained for Cd, Cr, Cu, Ni, and Pb using [A336][TS] after an extraction period of 5 h. For Ag and Pt, the phosphonium-based ionic liquids [C101][Sal] and [C101][Ant] showed the highest efficiency, only surpassed by Aliquat® 336 in the case of Ag extraction (97%).

Identification of inorganic dyeing mordant in textiles by surface-enhanced laser-induced breakdown spectroscopy

The identification of both the organic and inorganic fraction of dyes and pigments is fundamental for their complete characterization and to assess the technologies used in their production.In this work, the feasibility of determining metallic elements used as mordant for dyed textiles was tested using Laser-Induced Breakdown Spectrometry (LIBS) in combination with liquid micro-extraction. Both reference laboratory-dyed and historic textiles were analysed in this study. Samples were first analysed without any preparation. Then, the chromophores-containing molecules were separated using a sample preparation procedure based on aqueous hydrolysis, and analysed by high-pressure liquid chromatography coupled with a diode array detector. The same extracts, containing also the inorganic fraction, were analysed by Surface-Enhanced Laser-Induced Breakdown Spectroscopy (SENLIBS) after drying on a solid substrate.Compared to the direct analysis, the SENLIBS method improved the sensitivity of the measurements. The procedure presented here allowed for the characterization of both organic and inorganic fraction of a single textile micro sample, thus avoiding further sampling.

Switchable solvent based liquid phase microextraction of palladium coupled with determination by flame atomic absorption spectrometry

ABSTRACTA switchable solvent-based micro-extraction method for pre-concentration and separation of ultratrace palladium was developed prior to its flame atomic absorption spectrometric detection. Reverse change of hydrophilicity of N,N-dimethylcyclohexylamine (DMA) was achieved by reaction with carbonated water. The hydrophilic bicarbonate salt of the protonated DMA was used as extractant for palladium complexed with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP). Formation of the hydrophobic form of switchable solvent from hydrophilic form of switchable solvent phase was achieved by addition of sodium hydroxide into the extractant-sample solution. The effect of key parameters affected extraction recovery was studied and optimised by using Plackett–Burman design, central composite design and three dimension (3D) surfaces response. The calibration plot was linear in the range 0.015–1.6 mg L−1 of palladium with a correlation coefficient of 0.999. The limit of detections values of palladium for liquid and solid samples were 4.28 μg L−1 and 0.54 µg g−1, respectively. The pre-concentration factor was 37.5. The accuracy was confirmed by determination of palladium in certified reference material. The procedure was also applied for determination of palladium content of real samples as automotive catalytic converter, roadside dust, sea water and river water.

Ionic liquid solvent bar micro-extraction of CdCln(n−2)- species for ultra-trace Cd determination in seawater

Water analysis of trace metals has been benefited by recent studies on sample preparation by liquid micro-extraction. However, there are still limitations for its application to seawater, such as the need of additives to preserve the sample or the availability of chemical extractants for the selective extraction from highly saline samples.In this work, a three phase solvent bar micro-extraction (3SBME) system containing the ionic liquid trioctylmethylammonium chloride (Aliquat® 336) has been used for isolation and pre-concentration of Cd from seawater samples, due to its ability for ionic exchange of CdCln(n−2)-. The system was optimized to work at the natural pH of seawater, and conditions for application to real samples were 0.18 M Aliquat® 336 dissolved in kerosene with 0.25 M dodecan-1-ol as organic solution, 1.5 M HNO3 as acceptor solution, 60 min extraction time, and 800 rpm stirring speed in the sample. Loss of organic solution into the sample during extraction was evaluated and revealed its dependence on stirring rate and extraction time.Under optimum conditions samples containing Cd 0.09–0.90 nM were pre-concentrated 65 times. GF-AAS was used for metal quantification with a limit of detection of 0.04 nM. Accuracy was successfully evaluated measuring Cd in a seawater certified reference material BCR-403.

Methods of liquid phase microextraction for the determination of cadmium in environmental samples

Liquid phase microextraction (LPME) has been widely used in extraction and preconcentration systems as an excellent alternative to conventional liquid phase extraction. In this work, a critical review is presented on liquid phase microextraction techniques used in the determination of cadmium in environmental samples. LPME techniques are classified into three main groups: single-drop liquid phase microextraction (SDME), hollow fiber liquid phase microextraction (HF-LPME), and dispersive liquid-liquid microextraction (DLLME). Methods involving these liquid phase microextraction techniques are described, addressing advantages and disadvantages, samples, figures of merit, and trends.

Carbon-Based Nanomaterials Functionalized with Ionic Liquids for Microextraction in Sample Preparation

A large number of carbon-based nanomaterials has been investigated as sorbents in sample preparation, including fullerenes, carbon nanotubes, nanofibers, nanohorns and graphene, as well as their functionalized forms. Taking into account their properties, carbon-based nanomaterials have found a wide range of applications in different sample preparation techniques. Ionic liquids, as an alternative to environmentally-harmful ordinary organic solvents, have attracted extensive attention and gained popularity in analytical chemistry covering different fields like chromatography, electrochemistry and (micro)extraction. Some of the properties of ionic liquids, including polarity, hydrophobicity and viscosity, can be tuned by the proper selection of the building cations and anions. Their tunable nature allows the synthesis of tailor-made solvents for different applications. This review provides a snapshot of the most important features and applications of different carbon-based nanomaterials functionalized with ionic liquids for sample preparation. Emphasis is placed on the description of the different works that have provided interesting results for the use of graphene and carbon nanotubes, in this analytical field.

Spectrophotometric determination of total phenol in fish muscle after in- situ derivatization and reverse phase dispersive liquid- liquid microextraction

Spectrophotometric determination of total phenol in fish muscle after in- situ derivatization and reverse phase dispersive liquid- liquid microextraction

Occurrence of cocaine and metabolites in hospital effluent - A risk evaluation and development of a HPLC method using DLLME

A fast method for the determination of cocaine and its metabolites in hospital effluent samples was worked out by using liquid chromatography with the aid of fluorescence and diode array detection. Solid phase extraction and dispersive liquid –liquid microextraction were employed during the sample preparation stage. The experiment was conducted by using Chromabond® C18 ec 6 ml/500 mg cartridges, with recoveries higher than 96.6%, 88.3%, 78.7%, and LOQm 0.15; 0.18 and 0.30 μg L−1 for cocaine, benzoylecgonine and anhydroecgonine respectively. In the case of DLLME, different chemical conditions and solvent combinations were tested to find the best settings for the microextraction: pH 9; addition of 0.3 mol L−1 NaCl; 150 μL extractor (chloroform) and 350 μL disperser (methanol). The recoveries for cocaine were as high as 98.3% with LOQm 0.3 μg L−1. After validation, these methods were applied to quantification of the analytes. While the concentration of the anhydroecgonine, (the main pyrolytic metabolite of cocaine), remained below the limit of detection, the range of concentrations of cocaine and benzoylecgonine determined were 0.4–4.9 μg L−1 and 0.9–8.6 μg L−1, respectively. The occurrence has a relatively median/high environmental impact. These concentration values suggest that a role is played by other sources of cocaine, probably related to transport, or handling and the consumption of the drug. The outcome is that cocaine can be quantified by using DLLME as well as SPE, however, DLLME offered clear benefits like simplicity, affordability, and speed, as well as only requiring a small volume of solvents and samples.