Mixed Hemimicelles Solid-phase Extraction Research Articles

Mixed hemimicelles solid-phase extraction based on ionic liquid-coated Fe3O4/SiO2 nanoparticles for the determination of flavonoids in bio-matrix samples coupled with high performance liquid chromatography

A novel magnetic solid-phase extraction (MSPE) method based on mixed hemimicelles of room temperature ionic liquids (RTILs) coated Fe3O4/SiO2 nanoparticles (NPs) was developed for simultaneous extraction of trace amounts of flavonoids in bio-matrix samples. A comparative study on the use of RTILs (C16mimBr) and CTAB-coated Fe3O4/SiO2 NPs as sorbents was presented. Owing to bigger adsorption amounts for analytes, RTILs-coated Fe3O4/SiO2 NPs was selected as MSPE materials and three analytes luteolin, quercetin and kaempferol can be quantitatively extracted and simultaneously determined coupled with high performance liquid chromatography (HPLC) in urine samples. No interferences were caused by proteins or endogenous compounds. Good linearity (R2>0.9993) for all calibration curves was obtained, and the limits of detection (LOD) for luteolin, quercetin and kaempferol were 0.10ng/mL, 0.50ng/mL and 0.20ng/mL in urine samples, respectively. Satisfactory recoveries (93.5–97.6%, 90.1–95.4% and 93.3–96.6% for luteolin, quercetin and kaempferol) in biological matrices were achieved. It was notable that while using a small amount of Fe3O4/SiO2 NPs (4.0mg) and C16mimBr (1.0mg), satisfactory preconcentration factors and extraction recoveries for the three flavonoids were obtained. To the best of our knowledge, this is the first time a mixed hemimicelles MSPE method based on RTILs and Fe3O4/SiO2 NPs magnetic separation has ever been used for pretreatment of complex biological samples.

Magnetic Mixed Hemimicelles Solid-Phase Extraction of Three Food Colorants from Real Samples

Introducing a specific clean extraction procedure with a minimal matrices effect for food colorant determination is still a challengeable topic and highly recommended. Mixed hemimicelle solid-phase extraction method, based on cetyltrimethylammonium bromide-coated Fe3O4/SiO2 nanoparticles as a novel, simple, and fast preconcentration method, was applied for preconcentration and fast isolation of three synthetic food colorants in foodstuff matrices prior to HPLC-UV-vis determination. The influence of different parameters on extraction efficiency such as surfactant amount, sample pH, time of extraction, desorption condition, and nanoparticles concentration was optimized. Under the optimized conditions, a preconcentration factor of 100 was achieved by extracting 10 mL sample. The limit of detection for the three synthetic food colorants including Tartrazine, Sunset yellow FCF, and Quinoline yellow is 2.50, 1.25, and 2.12 μg/L, respectively. The proposed method was applicable for extraction and preconcentration of three food colorants in various food samples with the food dye contents in the range of 13–105 μg/L.

Preconcentration and speciation of Cr(III) and Cr(VI) in water and soil samples by spectrometric detection via use of nanosized alumina-coated magnetite solid phase

A novel nanomaterial has been developed for speciation of Cr(III) and Cr(VI) in water and soil samples. In this study, a new type of alumina-coated magnetite nanoparticles (Fe3O4/Al2O3 NPs) modified by the surfactant Triton X-114 has been successfully synthesized and used in magnetic mixed hemimicelles solid-phase extraction procedure. The procedure was based on the reaction of chromium(III) with 1-(2-pyridilazo)-2-naphtol as a ligand, yielding a complex, which was entrapped "in situ" in the surfactant hemimicelles. The concentration of chromium(III) was determined using flame atomic absorption spectrometry. After reduction of Cr(VI) to Cr(III) by ascorbic acid, the system was applied to the total chromium. Cr(VI) was then calculated as the difference between the total Cr and the Cr(III) content. This method can also be used for complicated matrices such as soil samples without any special pretreatment. Under the optimum conditions of parameters, the recoveries of Cr(III) by analyzing the spiked water and soil samples were between 98.6 and 100.8 % and between 96.5 and 100.7 %, respectively. Detection limits of Cr(III) were between 1.4 and 3.6 ng mL(-1) for water samples and 5.6 ng mg(-1) for soil samples.

Mesoporous Silica‐coated Magnetic Nanoparticles for Mixed Hemimicelles Solid‐phase Extraction of Phthalate Esters in Environmental Water Samples with Liquid Chromatographic Analysis

AbstractTo extract, preconcentrate and determine the trace level of environmental contaminants, a novel mixed hemimicelles solid‐phase extraction (MHSPE) method based on mesoporous silica‐coated magnetic nanoparticles (Fe3O4/meso‐SiO2 NPs) as adsorbent was developed for extraction of phthalate esters from water samples. The Fe3O4/meso‐SiO2 NPs were synthesized by using a combination of hydrothermal method and sol‐gel method. The obtained Fe3O4/meso‐SiO2 NPs possessed a large surface area (570 m2/g), superparamagnetism, and uniform mesopores (2.8 nm). MHSPE parameters, such as the amount of surfactant, pH of sample, shaking and separation time, eluent and breakthrough volume that may influence the extraction of analytes greatly, were further investigated. Under the optimized conditions, the extraction was completed in 20 min and a concentration factor of 500 was achieved by extracting 250 mL water sample. Detection limits obtained of butyl‐benzyl phthalate (BBP), di‐n‐butyl phthalate (DnBP), di‐(2‐ethylhexyl) phthalate (DEHP) and di‐n‐cotyl phthalate (DnOP) were 12, 21, 12, and 32 ng/L, respectively. The proposed method exhibited high extraction efficiency and relatively short time for extracting the target compounds.

Mixed hemimicelles solid-phase extraction of chlorophenols in environmental water samples with 1-hexadecyl-3-methylimidazolium bromide-coated Fe 3O 4 magnetic nanoparticles with high-performance liquid chromatographic analysis

In this paper, 1-hexadecyl-3-methylimidazolium bromide (C 16mimBr)-coated Fe 3O 4 magnetic nanoparticles (NPs) as an adsorbent of mixed hemimicelles solid-phase extraction was investigated for the preconcentration of two chlorophenols (CPs) in environmental water samples prior to HPLC with UV detection at 285 nm. The high surface area and excellent adsorption capacity of the Fe 3O 4 NPs after modification with C 16mimBr were utilized adequately in the SPE process. By the rapid isolation of Fe 3O 4 NPs through placing a strong magnet on the bottom of beaker, the time-consuming preconcentration process of loading large volume sample in conventional SPE method with a column can be avoided. A comprehensive study of the adsorption conditions such as the zeta-potential of Fe 3O 4 NPs, added amounts of C 16mimBr, pH value, standing time and maximal extraction volume were also presented. Under optimized conditions, two analytes of 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP) were quantitatively determined. The method was then used to determine the two CPs in real environmental water samples. The accuracy of method was evaluated by recovery measurements on spiked samples. Good recovery results (74–90%) were achieved. It is important to note that satisfactory preconcentration factors and extraction recoveries for the two CPs were obtained with only a small amount of Fe 3O 4 NPs (40 mg) and C 16mimBr (24 mg).

Magnetic mixed hemimicelles solid‐phase extraction of xanthohumol in beer coupled with high‐performance liquid chromatography determination

In this study, silica-coated magnetic nanoparticles (Fe(3)O(4)/SiO(2) NPs) modified by cetyltrimethylammonium bromide (CTAB) were synthesized. They were successfully applied for extraction of xanthohumol in beer based on magnetic mixed hemimicelles solid-phase extraction (MMHSPE) coupled with high-performance liquid chromatography-ultraviolet determination. The main factors influencing the extraction efficiency including the surfactant amount, the beer pH, the extraction time, the desorption condition and the maximum extraction beer volume were optimized. Under the optimized conditions, a concentration factor of 60 was achieved by extracting 120 mL beer sample using MMHSPE and the detection limit of xanthohumol is 0.0006 mg/L. The proposed method was successfully applied for determination of xanthohumol in various beer samples with the xanthohumol contents in the range of 0.031-0.567 mg/L. The satisfactory recoveries (90-103%) were obtained in analyzing spiked beer samples.

Ionic liquid-coated Fe3O4 magnetic nanoparticles as an adsorbent of mixed hemimicelles solid-phase extraction for preconcentration of polycyclic aromatic hydrocarbons in environmental samples

In this paper, ionic liquid (IL)-coated magnetic Fe(3)O(4) nanoparticles (NPs) as an adsorbent of mixed hemimicelles solid-phase extraction (SPE) was investigated for the preconcentration of polycyclic aromatic hydrocarbons (PAHs) from environmental samples. Due to the high surface area and excellent adsorption capacity of the Fe(3)O(4) NPs after modification with ILs, satisfactory extraction recoveries can be achieved with only 80 mg Fe(3)O(4) NPs, 50 mg IL, 300 mL solution at pH = 10 and 10 min for equilibration. A comprehensive study of the adsorption conditions such as the amount of Fe(3)O(4) NPs and ILs, the solution pH, ionic strength, standing time, breakthrough volume, and desorption solvents was presented. The extraction ability of different coating agents, such as 1-hexadecyl-3-methylimidazolium bromide (C(16)mimBr), 1-decyl-3-methylimidazolium bromide (C(10)mimBr) and cationic surfactant cetyltrimethylammonium bromide (CTAB) was also compared. Under the optimized conditions, the recoveries for the water samples analysis were between 76 and 105% with relative standard deviations (RSDs) ranging from 3.9 to 6.9%, and the recoveries for soil samples were between 73 and 104% with RSDs ranging from 1.0 to 6.3%. In this method, only a small amount of C(16)mimBr (50 mg) and Fe(3)O(4) NPs (80 mg) was needed to obtain satisfactory recoveries.

Mixed hemimicelles SPE based on CTAB-coated Fe3O4/SiO2 NPs for the determination of herbal bioactive constituents from biological samples

In this paper, a solid-phase extraction (SPE) method based on mixed hemimicelles of cetyltrimethyl ammonium bromide (CTAB) on silica-coated magnetic nanoparticles (MNPs) is developed for extraction and preconcentration of compounds from the biological samples. We selected rhein and emodin which are the major active anthraquinones of rhubarb as model analytes. A high performance liquid chromatography-fluorescence detection (HPLC/FLD) method was developed for the determination of rhein and emodin in urine and serum samples. The main factors influencing the extraction efficiency including the amount of surfactant, the concentration of MNPs, the shaking time and the desorption ability of organic solvents were investigated and optimized. No interferences were caused by proteins or endogenous compounds in urine and serum samples. Good linearities (r(2)>0.9995) for all calibration curves were obtained, and the limits of detection (LODs) for rhein and emodin were 0.2 and 0.5 ng/mL in urine samples and 7 and 10 ng/mL in serum samples, respectively. Satisfactory recoveries (92.76-109.90% and 97.53-107.72% for rhein and emodin) in the biological matrices were achieved.

Analysis of sulfonamides in environmental water samples based on magnetic mixed hemimicelles solid-phase extraction coupled with HPLC–UV detection

The magnetic mixed hemimicelles solid-phase extraction (MMHSPE), based on the adsorption of cation surfactant octadecyltrimethylammonium bromide (OTMABr) onto magnetite nanoparticles (Fe 3O 4 NPs) to form mixed hemimicelles, was proposed for the preconcentration of several sulfonamides (SAs) compounds including sulfamethoxazole (SMX), sulfamethoxydiazine (SMD), sulfadimethoxine (SDM) and sulfaquinoxaline (SQX) from environmental water samples. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of OTMABr-coated Fe 3O 4 NPs with an adscititious magnet. Mixed hemimicelles formed on the surface of Fe 3O 4 NPs by OTMABr showed great adsorptive tendency towards analytes. The OTMABr-coated Fe 3O 4 NPs adsorbents were easy to be prepared, low cost and environmentally friendly. A comprehensive study on the adsorption conditions such as the amount of the surfactant, the solution pH, the desorption condition and the maximum extraction sample volume were optimized. A concentration factor of 1000 was achieved by the extraction of 500 mL of environmental water samples using MMHSPE. Detection limits obtained for SMX, SMD, SDM and SQX were 0.026, 0.024, 0.033 and 0.030 μg L −1, respectively. Good recoveries (70–102%) with low relative standard deviations (1–6%) were achieved in analyzing spiked water samples. Low concentration of SQX was found in hospital primary and final sewage effluent sample.

Preparation of alumina-coated magnetite nanoparticle for extraction of trimethoprim from environmental water samples based on mixed hemimicelles solid-phase extraction

In this study, a new type of alumina-coated magnetite nanoparticles (Fe 3O 4/Al 2O 3 NPs) modified by the surfactant sodium dodecyl sulfate (SDS) has been successfully synthesized and applied for extraction of trimethoprim (TMP) from environmental water samples based on mixed hemimicelles solid-phase extraction (MHSPE). The coating of alumina on Fe 3O 4 NPs not only avoids the dissolving of Fe 3O 4 NPs in acidic solution, but also extends their application without sacrificing their unique magnetization characteristics. Due to the high surface area of these new sorbents and the excellent adsorption capacity after surface modification by SDS, satisfactory concentration factor and extraction recoveries can be produced with only 0.1 g Fe 3O 4/Al 2O 3 NPs. Main factors affecting the adsolubilization of TMP such as the amount of SDS, pH value, standing time, desorption solvent and maximal extraction volume were optimized. Under the selected conditions, TMP could be quantitatively extracted. The recoveries of TMP by analyzing the four spiked water samples were between 67 and 86%, and the relative standard deviation (RSD) ranged from 2 to 6%. Detection and quantification limits of the proposed method were 0.09 and 0.24 μg L −1, respectively. Concentration factor of 1000 was achieved using this method to extract 500 mL of different environmental water samples. Compared with conventional SPE methods, the advantages of this new Fe 3O 4/Al 2O 3 NPs MHSPE method still include easy preparation and regeneration of sorbents, short times of sample pretreatment, high extraction yields, and high breakthrough volumes. It shows great analytical potential in preconcentration of organic compounds from large volume water samples.

Cetyltrimethylammonium Bromide-Coated Magnetic Nanoparticles for the Preconcentration of Phenolic Compounds from Environmental Water Samples

The research presented in this paper investigates the adsorption of cation surfactants--cetyltrimethylammonium bromide (CTAB) and cetylpyridinium chloride (CPC)--onto magnetic nanoparticles and the application of this mixed hemimicelles solid-phase extraction (SPE) method for the preconcentration of several typical phenolic compounds-bisphenol A (BPA), 4-tertoctylphenol (4-OP), and 4-n-nonylphenol (4-NP)--from environmental water samples. In this novel SPE method, the charged surfactants CTAB and CPC form mixed hemimicelles on Fe3O4 nanoparticles (Fe3O4 NPs), which causes retention of analytes by strong hydrophobic and electrostatic interactions. The SPE method combines the advantages of mixed hemimicelles and magnetic nanoparticles. In order to provide guidelines forthe mixed hemimicelles SPE method development, surfactant adsorption isotherms and zeta-potential isotherms were also investigated. The main factors affecting the adsolubilization of analytes, such as the amount of Fe3O4 NPs and surfactants, the type of surfactants, the solution pH,the sample loading volume, and the desorption conditions, were investigated and optimized. A concentration factor of 800 was achieved by the extraction of 800 mL of several environmental water samples using this SPE method. Under the selected conditions, detection limits obtained for BPA, 4-OP, and 4-NP were 12, 29, 34 ng/L, respectively. The accuracy of the method was evaluated by recovery measurements on spiked samples, and good recoveries (68-104%) with low relative standard deviations from 2 to 7% were achieved. The advantages of this new SPE method include high extraction yields, high breakthrough volumes, short analysis times, and easy preparation of sorbents. To the best of our knowledge, this is the first time that a mixed hemimicelles SPE method based on magnetic separation and nanoparticles has been used for the pretreatment of environmental water samples.

Mixed hemimicelles solid-phase extraction based on cetyltrimethylammonium bromide-coated nano-magnets Fe 3O 4 for the determination of chlorophenols in environmental water samples coupled with liquid chromatography/spectrophotometry detection

Mixed hemimicelles solid-phase extraction (SPE) based on cetyltrimethylammonium bromide (CTAB)-coated nano-magnets Fe 3O 4 was investigated for the preconcentration of four chlorophenols (CPs) in environmental water samples prior to HPLC–spectrophotometry determination in this paper. By the rapid isolating (about 5 min) of Fe 3O 4 nanoparticles (NPs) through placing a Nd–Fe–B strong magnet on the bottom of beaker, the time-consuming preconcentration process of loading large volume sample in conversional SPE method with a column can be avoided. The unique properties of Fe 3O 4 NPs such as high surface area and strong magnetism were utilized adequately in the SPE process. This novel separation method produced a high preconcentration rate and factor. A comprehensive study of the adsorption conditions such as the Fe 3O 4 NPs zeta-potential, CTAB added amounts, pH value, standing time and maximal extraction volume was also presented. Under optimized conditions, four analytes of 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) were quantitatively extracted. The method was then used to determine four CPs in five real environmental water samples. High concentration factors (700) were achieved for each of the analytes, with observed detection limits ranging between 0.11 and 0.15 μg L −1. The accuracy of method was evaluated by recovery measurements on spiked samples. Good recovery results (83–98%) with satisfactory relative standard deviation (RSD) were achieved. It is important to note that satisfactory preconcentration factors and extraction recoveries for the four CPs were obtained with only a little amount of Fe 3O 4 NPs (0.1 g) and CTAB (60 mg). To the best of our knowledge, this was the first time a mixed hemimicelles SPE method based on Fe 3O 4 NPs magnetic separation had been used for the pretreatment of environmental water samples.

Determination of sulfonamide compounds in sewage and river by mixed hemimicelles solid-phase extraction prior to liquid chromatography–spectrophotometry

Mixed hemimicelles-based solid-phase extraction was investigated for the preconcentration of five sulfonamides from environmental water samples prior to HPLC–spectrophotometry determination in this paper. A comparative study on the use of sodium dodecyl sulfate (SDS) coating γ-alumina or octadecyltrimethylammonium bromide (OTMABr) and OTMABr coating silica as sorbent materials were presented. The five analytes (sulfadiazine (SDA), sulfathiazole (STA), sulfapyridine (SPD), sulfamethazine (SMZ) and sulfamethoxazole (SMX)) were quantitatively adsorbed on OTMABr-γ-alumina and OTMABr-silica mixed hemimicelles, but OTMABr-γ-alumina was not adopted because it worked at a high pH (around 10), instead, OTMABr-silica was selected to overcoming the pH restriction. The analytes retained on the cartridge were quantitatively desorbed with suitable amounts of methanol. Factors influencing the extraction efficiency, such as the amount of surfactant, pH of sample and breakthrough volume were discussed. The proposed method had been applied to determining the five sulfonamides in several environmental water samples and concentration factors of 300 and 600 for SDA and other four analytes were achieved, respectively. Detection limits obtained ranged between 0.15 and 0.35 μg/L for this five sulfonamides under the optimized conditions. The accuracy of the method was evaluated by recovery measurements on spiked samples, and good recovery results (89–113%) with precision of 3–6% were achieved.