Ionic liquid enhanced magnetic solid-phase extraction of phthalate esters in food samples with oleic acid coated-Fe3O4 nanoparticles prior to HPLC

A novel method based on ionic liquid enhanced magnetic solid-phase extraction (MSPE) coupled with high-performance liquid chromatography (HPLC) for the separation/analysis of phthalate esters (PAEs) in food samples was established. 1-hexyl-3-methylimidazoliu-hexafluorophosphate ([C₆MIM][PF₆]) was used to coat oleic acid Fe₃O₄ nanoparticles with core–shell structures to prepare MSPE agents (Fe₃O₄@OA@IL). The main parameters affecting the extraction efficiency of PAEs were studied. Under the optimal conditions, the calibration curves were linear in the range of 5–5000 ng mL^?1 (R² = 0.9972–0.9998) of four PAEs. The limit of detections (LODs) and relative standard deviations (RSDs, n = 5) of the method were 1.27–2.95 ng mL^?1 and 3.9–5.3%, respectively.     

FACILE ANALYSIS OF CARBAZOLE IN COMMERCIAL ANTHRACENE BY HEAVY ATOM–INDUCED ROOM TEMPERATURE PHOSPHORESCENCE

The applicability of heavy atom–induced room temperature phosphorescence (HAI-RTP) in real samples is demonstrated in this work. In this methodology only two reagents, potassium iodide as heavy atom salt and sodium sulfite as oxygen scavenger, were used to obtain the phosphorescent signal of carbazole in solution while anthracene did not show phosphorescence under these experimental conditions. In this study a new simple, rapid, and selective phosphorimetric method is proposed, using HAI-RTP methodology for the determination of carbazole in high-purity anthracene. The phosphorescence intensity was measured at 438 nm with excitation at 290 nm. Phosphorescence was fully developed instantly. A linear concentration range between 0 and 250 ng/mL^?1 with a detection limit of 1.05 ng/mL^?1 (10.5 ng of CBZ in 600 ng of anthracene), an analytical sensitivity of 1.7 ng/mL^?1, and standard deviation of 0.71% at 150 ng/mL^?1 concentration level was obtained. The method has been successfully applied to the analysis of carbazole in spiked anthracene samples.     

Cloud Point Extraction and Spectrophotometric Determination of Sulfide in Water Samples using Ethylene Blue Formation Reaction

Abstract

A rapid, selective, and sensitive cloud point extraction process using mixed micelle of a nonionic surfactant, Triton X-114, and an anionic surfactant, SDS, to extract sulfide from aqueous solutions was investigated. The method is based on the color reaction of sulfide with N,N-diethyl-p-phenylenediamine (DPD) in the presence of suitable oxidizing reagent (Fe³⁺) in acid media and cloud point extraction of ethylene blue (EB) dye. Various factors and optimal extraction and reaction conditions like: acid, Fe³⁺, reagent, and surfactant concentration were studied and the analytical characteristics of the method (e.g., limit of detection, linear range, RSD%) were obtained. Linearity was obeyed in the range of 1–100 ng mL^?1 of sulfide ion. The detection limit of the method is 0.5 ng mL^?1 of sulfide ion. The interference effect of some anions, cations, and neutral species was also tested. The method was applied to the determination of sulfide in spring, river, and waste water samples.     

Response surface methodology for optimization and determination of Riluzole by microfunnel magnetic stirring-assisted liquid–liquid microextraction coupled with high-performance liquid chromatography

ABSTRACT

A rapid, simple, and highly sensitive microfunnel magnetic stirring-assisted liquid–liquid microextraction coupled with HPLC was developed for determination of Riluzole (RLZ). The main extraction parameters were screened using the Plackett–Burman design and optimized by central composite design. Under optimum conditions, the calibration curve was linear over the range of 0.2–400 ng mL^?1, and RSD of 3.21% (n = 14, 20 ng mL^?1) proved to have good reproducibility. The detection limit was 0.023 ng mL^?1 and 1.5 ng mL^?1 for aqueous and biological samples, respectively. The tap water, human plasma, and urine samples showed excellent recoveries for RLZ (97.09–101.92%) via this method.     

Sensitive Colorimetric Detection of Explosive 2,6‐Bis(picrylamino)pyridine after Preconcentration by Dispersive Liquid‐Liquid Microextraction

An experimental investigation for sensitive spectrophotometric detection of explosive, 2,6‐bis(picrylamino)pyridine (BPAP) using dispersive liquid‐liquid microextraction was carried out. Based on this procedure, which is a dispersive‐solvent‐free technique, the extractant is dispersed in the aqueous sample solution using Aliquat 336 (acted as disperser agent and carrier to extraction solvent) and monitored with microvolume UV/Vis spectrophotometer. The effect of different variables such as pH, concentration of sodium hydroxide, type and volume of extraction solvent, concentration of Aliquat 336 solution and coexisting substances were systematically investigated and optimized. Interference tests showed that the developed method has a good selectivity and could be used conveniently for determination of explosive analyte. The proposed method is capable of determining BPAP over a range of 2.0–150.0 ng mL⁻¹ with a limit of detection 1.0 ng mL⁻¹. Relative standard deviations (RSD) for 20.0 and 80.0 ng mL⁻¹ of BPAP were 3.3 and 1.2 % (n=10), respectively. This colorimetric method was applied to determine BPAP in different water and soil samples.     

Separation and Preconcentration of Silver Ion using Multiwalled Carbon Nanotubes as Solid Phase Extraction Sorbent

Abstract

A new method has been developed for the determination of silver ion based on separation and preconcentration with a microcolumn packed with multiwalled carbon nanotubes (MWNTs) prior to its determination by flame atomic absorption spectrometry (FAAS). The optimum experimental parameters for separation and preconcentration of silver, `such as sample pH, sample flow rate and volume, elution conditions, and interfering ions, have been investigated. Silver ion can be quantitatively retained by MWNTs in the pH range 7～9, and then eluted completely with 1.0 M HNO₃. The detection limit of this method for Ag was 0.60 ng mL^?1, and the relative standard deviation (RSD) was 3.8% at the 10 ng mL^?1 Ag level. The method has been successfully applied for the determination of trace silver in geological and water samples.     

Low-density solvent-based dispersive liquid–liquid microextraction coupled with hydrophobic magnetic nanoparticles for determination of synthetic phenolic antioxidants in vegetable oils by high-performance liquid chromatography

A novel and rapid low-density solvent-based dispersive liquid–liquid microextraction technique combined with magnetic solid-phase extraction (MSPE) was developed for preconcentration and separation of synthetic phenolic antioxidants (SPAs) in vegetable oils prior to high-performance liquid chromatography. 1-Heptanol was used as extractant and decanoic acid@Fe₃O₄ nanoparticles (DA@Fe₃O₄ NPs) as carrier to retrieve and separate the 1-heptanol. In that manner, the upper extractant containing the SPAs is the target of the MSPE step rather than the SPAs directly. Thanks to the interaction between carboxyl group present on the surface of the magnetic nanoparticles and the alcohol functional group of the extractant, the DA@Fe₃O₄ NPs facilitates the recollection of the 1-heptanol after extraction. The main parameters affecting the extraction recoveries of four SPAs were investigated, and the proposed method provided a good linearity in the range of 50–2000 ng mL^?1, low limits of detection (1.2–5.8 ng mL^?1), and good repeatability of the extractions (relative standard deviations ≤6.7%, n = 5), and recoveries were ranged from 90.2% to 99.5%.     

Factorial Design Optimization of Solid-Phase Microextraction for High-Performance Liquid Chromatography−Ultraviolet Spectrometry Analysis of Polycyclic Aromatic Hydrocarbons in Cigarette Filter Tar

A simple and rapid procedure for the determination of polycyclic aromatic hydrocarbons (PAHs) in cigarette filter tar using solid-phase microextraction (SPME) was developed. The analysis was carried out using high-performance liquid chromatography equipped with an ultraviolet detector. The effects of the SPME experimental parameters on the extraction recovery were studied simultaneously using a central composite design (CCD) after a 2^6?2 fractional factorial experimental design. The SPME variables of interest were the extraction temperature, the extraction time, and the stirring speed, as well as the pH and the concentrations of NaCl (%, w/v) and acetonitrile (ACN). The optimal SPME conditions were as follows: an extraction temperature of 65°C, an extraction time of 50 min, a stirring speed of 800 rpm, 0% NaCl (w/v), 10% ACN in the sample, and a source pH of 8.0. The extraction calibration plots were linear over the range of 0.25?20 ng mL^?1 (r² > 0.9912) and the limits of detection (LODs) for the 6 PAHs studied were from 0.17–5.02 ng cigarette^?1. The relative standard deviation (RSD) ranged from 7.1–13.5% for intra-day variation and from 8.5–18.4% for inter-day variation. The performance of the proposed method was evaluated for extraction and determination PAHs in real samples (various brands of cigarettes). The total amounts of all of the studied PAHs found in the filter tar of the three brands of cigarettes were 320.2, 17.9, and 66.7 ng cigarette^?1, respectively.     

Micelle-Mediated Extraction and Cloud Point Preconcentration of Chlorophylls from Spinach

A micelle-mediated extraction and cloud point preconcentration of chlorophylls method was developed. Non-ionic surfactant (Genapol X-080) was employed as an alternative and effective extraction solvent. The optimal extraction parameters based on the micelle extraction technique were determined. Under optimal conditions, i.e., 5% Genapol X-080 (v/v), pH 9.0, liquid/solid ratio of 10:1 (mL g^?1), ultrasonic-assisted extraction for 30 min, extraction amount reached the highest value. For the preconcentration of chlorophylls by cloud point extraction (CPE), the solution was incubated at 50° for 30 min, and 0.1 g mL^?1 sodium chloride was added to the solution to facilitate the phase separation. The microstructure of coacervate phase after CPE was explored with transmitting electron microscopy. The preconcentration factor for chlorophylls was about 12.5, the extraction recovery approached 99.2%, and the loading capacity was about 1 mg mL^?1. Thus coupling of ultrasonic-assisted micelle extraction and cloud point extraction could be employed as a new and effective technique for the rapid extraction and preconcentration of chlorophylls from plants such as spinach.     

Micelle‐Mediated Extraction for Direct Spectrophotometric Determination of Trace Uranium(VI) in Water Samples

Abstract

The possibility of using Dibenzoylmethane (DBM) for uranium(VI) concentrating by the way of micellar extraction at cloud point temperature and later spectrophotometric determination was investigated. Under the optimum conditions, preconcentration of 50 mL of water samples in the presence of 0.2% (w/v) octylphenoxypolyethoxy ethanol (Triton X‐114), 2×10^?4 mol L^?1 DBM and 2×10^?3 mol L^?1 buffer solution (pH=9) gave a limit of detection 11 ng mL^?1, and the calibration graph was linear in the range of 15–300 ng mL^?1. The recovery under optimum working conditions was higher than 98%.

The proposed method has been applied to the spectrophotometric determination of uranium(VI) in natural water samples after cloud point extraction with satisfactory results.     

Spectrophotometric Determination of Benzalkonium Bromide in Pharmaceutical Samples with Alizarin Green

A direct, extraction‐free spectrophotometric method was developed for the determination of benzalkonium bromide (BAK). The method is based on the formation of mixed dye–surfactant aggregates between alizarin green (AG) and BAK in alkaline medium by measuring the decrease in absorbance of AG at 460 and 700 nm. Beer's law was obeyed in the concentration range 3–40 μg mL^?1 with good precision and accuracy. The limits of detection were 0.4 μg mL^?1 at 460 nm and 0.3 μg mL^?1 at 700 nm, which reduced to 0.2 μg mL^?1 by combining the absorbance at the two wavelengths. The proposed method was successfully applied to the determination of BAK in disinfectant solution and eye drops. The analytical results of the real samples were in good agreement with those of an HPLC method.     

Extraction of Human IgG4 Monoclonal Antibodies Using AOT- and HDEHP-Isooctane Reverse Micelles

The extraction of 0.05 and 1 mg mL^?1 human IgG4 using reverse micelles (RMs) formed with anionic surfactants AOT or HDEHP in isooctane was evaluated. For both surfactants the use of 1 mg mL^?1 IgG4 resulted in higher forward extraction (FE), and generally better backward extraction (BE) yields than 0.05 mg mL^?1 IgG4, achieving optimum FE and BE yields at FE pHs of 5 at 3.13 mM AOT and 6 at 1.56 mM HDEHP. IgG4 precipitation at the interface was observed at the lower pHs during FE which appeared to cause low overall extraction yields. Water content analysis revealed AOT-RMs were much bigger than HDEHP-RMs.     

Surfactant‐Assisted Dispersive Liquid–Liquid Microextraction for Sensitive Spectrophotometric Determination of Iron in Food and Water Samples and Comparison with Atomic Absorption Spectrometry

A technique of selective and sensitive surfactant‐assisted dispersive liquid–liquid microextraction combined with spectrophotometry was developed for determination of iron in water and food samples. This method involves the formation of a red‐colored iron‐thiocyanate complex in the presence of cetyltrimethylammonium bromide (CTAB) as cationic surfactant. The use of CTAB assisted in color formation and effective extraction of the complex into the organic solvent through micelle formation prior to spectrophotometric and flame atomic absorption spectrometry measurement. Optimum absorbance and extraction of the iron complex was obtained with concentrations of ammonium thiocyanate, N‐phenylbenzimidoyl thiourea, CTAB and sodium chloride of 0.30 M, 3.0 × 10^?3 M, 0.40 × 10^?3 M and 1.0 %, respectively. The calibration curve was linear over a range of 20–350 ng mL^?1 iron with correlation of estimation (R²) of 0.997. The proposed method was successfully applied to the determination of iron in food (cereal, fruit and vegetable) and water samples.     

Rotative Liquid-Liquid Microextraction as a Preconcentration Method in Combination with Fiber Optic-Linear Array Detection Spectrophotometry for the Determination of Cobalt in Pharmaceutical Samples

A new and fast solvent microextraction method, termed rotative liquid-liquid microextraction (RLLME), has been introduced and used for real sample analysis. RLLME in combination with fiber optic-linear array detection spectrophotometry was used for pharmaceutical sample analysis. The proposed method was compared with other methods and its applicability was evaluated by the determination of cobalt in pharmaceutical samples including B₁₂ ampoule, B-complex ampoule, and Neobion ampoule, as well as Centrum capsule as a nutritive supplement. Accuracy of the method was proved using certified reference material.

Under the optimum conditions, the preconcentration time was 30 s, which is one of the shortest preconcentration times reported to date. The calculated calibration curves gave high levels of correlation coefficients (r²) greater than 0.9993, the limit of detection (LOD) of the method was 0.12 ng mL^?1, and the relative standard deviation (R.S.D.) was 1.9 % for 50 ng mL^?1 cobalt.     

Determination of Iron and Copper in Edible Oils by Flame Atomic Absorption Spectrometry After Liquid–Liquid Extraction

In the present work, a novel and rapid extraction method for Fe(III) and Cu(II) from liquid edible oils is described. N,N′‐Bis(4‐methoxysalicylidene)‐1,2‐diamino ethane (MSE) was utilized for the extraction of metal ions and the determination was achieved by flame atomic absorption spectrometry (FAAS). In order to optimize the extraction conditions, a central composite design (CCD) technique was employed. The optimum conditions, the ratio of MSE solution volume to oil mass, stirring time and temperature, were determined as 1.2 and 1.1 mL g^?1; 24.0 and 31.8 min and 25.3 and 33.2 °C for Fe(III) and Cu(II) extraction, respectively. The feasibility of the improved method was tested with oil‐based metal standards affording 98.6 % recovery for both metals and 67.3 ng g^?1 for Fe(III) and 15.3 ng g^?1 for Cu(II) as limit of detection (LOD).     

Effect of sonication assisted by titanium dioxide and ferrous ions on polyaromatic hydrocarbons (PAHs) and toxicity removals from a petrochemical industry wastewater in Turkey

BACKGROUND: In Izmir (Turkey) polyaromatic hydracarbon (PAH) removal efficiencies are low in petrochemical industry aerobic biological wastewater treatment plants because bacteria are not able to overcome the inhibition of these toxic and refractory organics. In order to increase PAHs removal, sonication process was chosen among other advanced treatment processes include sonication processes. The effects of ambient conditions, increasing sonication time, sonication temperature, TiO₂ and Fe⁺² concentrations on sonication at a petrochemical industry wastewater treatment plant in Izmir (Turkey) was investigated in a 650 W sonicator, at a frequency of 35 kHz and a 500 mL glass reactor. RESULTS: Increasing the temperature improved PAH removal after 150 min sonication at 30 °C and 60 °C. The maximum total PAH removal efficiencies were the same in a reactor containing 20 mg L^?1 TiO₂ and in a TiO₂‐free reactor at 30 °C and 60 °C after 150 min sonication. Maximum 91% and 97% total PAH removals were obtained in a control reactor and a reactor containing 20 mg L^?1 Fe⁺² at 30 °C and 60 °C, respectively, after 150 min sonication. The PAH concentration was toxic to Daphnia magna, so that the EC₅₀ value decreased significantly from 342.56 ng mL^?1 to EC₅₀ = 9.88 ng mL^?1 and to EC₅₀ = 3.35 ng mL^?1, at the lowest TiO₂ (0.1 mg L^?1) and Fe⁺² (2 mg L^?1) concentrations, respectively, after 150 min sonication at 30 °C. CONCLUSION: PAHs and the acute toxicity in a petrochemical industry wastewater were removed efficiently through sonication. Copyright © 2010 Society of Chemical Industry     

Extraction of Ultra Trace Amounts of Palladium on 9-Acridinylamine Functionalized SBA-15 and MCM-41 Nanoporous Silica Sorbents

The application of the modified MCM-41 and SBA-15 nanporous silicas in extraction of trace amounts of palladium is investigated and developed. Surface of nanoporous silicas, MCM-41 and SBA-15, were modified with 9-acridinylamine ligand and then utilized as solid-phase sorbents for the extraction of palladium. Different experimental conditions such as pH, flow rates of the sample, and eluent solution were studied. The type and the smallest amount of eluent for elution were optimized and the breakthrough volume and the influence of various cationic interferences on the adsorption was investigated. The recovery values in this method are greater than 95% and 98.5%. The obtained limits of detections (LOD) are lower than 0.17 ng mL^?1 and 0.15 ng mL^?1 for SBA-15 and MCM-41, respectively. The pre-concentration factors were calculated to be more than 193 and 187.5 for SBA-15 and MCM-41, respectively. The relative standard deviations (RSD) of the method are lower than 4% and 1.5%, and the adsorption capacities were also obtained to be more than 170 mg g^?1 and 195 mg g^?1 for SBA-15 and MCM-41, respectively. The proposed procedure was applied on real samples and the amount of palladium was successfully derived.     

Vortex-assisted dispersive liquid–liquid microextraction trace amounts of melatonin prior to HPLC determination in fruit juice samples

In the present study, a fast, simple and sensitive vortex-assisted dispersive liquid–liquid microextraction method was developed for extraction and preconcentration of trace amounts of melatonin in fruit juice samples. The extraction conditions were optimized as extraction solvent, chloroform; volume of extracting, 200.0 μL; and vortex time, 120 s. The HPLC determinations were done using ODS Waters C₁₈ column under gradient elution. The calibration curve was linear in the range of 1.0–1000.0 ng mL^–1 and detection limit was 0.23 ng mL^–1. The validated method was applied for separation and determination of melatonin in different fruit juice samples (cherry, tomato and grape).     

Simultaneous extraction and determination of lead, cadmium and copper in rice samples by a new pre-concentration technique: Hollow fiber solid phase microextraction combined with differential pulse anodic stripping voltammetry

In the present work, a novel solid phase microextraction (SPME) technique using a hollow fiber-supported sol–gel combined with multi-walled carbon nanotubes, coupled with differential pulse anodic stripping voltammetry (DPASV) was employed in the simultaneous extraction and determination of lead, cadmium and copper in rice. In this technique, an innovative solid sorbent containing mixture of carbon nanotube and a composite microporous compound was developed by the sol–gel method via the reaction of tetraethylorthosilicate (TEOS) with 2-amino-2-hydroxymethyl-propane-1,3-diol (TRIS). The growth process was initiated in basic condition (pH 10–11). Afterward this sol was injected into a polypropylene hollow fiber segment for in situ gelation process. The main factors influencing the pre-concentration and extraction of the metal ions; pH of the aqueous feed solution, extraction time, aqueous feed volume, agitation speed, the role of carbon nanotube reinforcement (as-grown and functionalized MWCNT) and salting effect have been examined in detail. Under the optimized conditions, linear calibration curves were established for the concentration of Cd(II), Pb(II) and Cu(II) in the range of 0.05–500, 0.05–500 and 0.01–100 ng mL⁻¹, respectively. Detection limits obtained in this way are, 0.01, 0.025 and 0.0073 ng mL⁻¹ for Cd(II), Pb(II) and Cu(II), respectively. The relative standard deviations (RSDs) were found to be less than 5% (n = 5, conc.: 1.0 ng mL⁻¹).     

Solvent extraction separation and spectrophotometric determination of ruthenium(III) with p-methylphenyl thiourea: sequential separation of ruthenium,osmium and iron

ABSTRACT

A selective and sensitive solvent extraction and spectrophotometric study of the ruthenium(III)–p-methylphenyl thiourea (PMPT) system is presented. The optimum conditions were determined by a critical study of acid concentration, reagent concentration, equilibration period, heating time and effect of solvent on the equilibrium. Ruthenium(III) forms 1:1 complex with PMPT in 20% ethanol and extracted into chloroform. Conformity to Beer’s law at 600 nm was observed up to 40 µg mL^–1 of ruthenium. Molar absorptivity and Sandell’s sensitivity were found to be 2.31 × 10³ L mol^?1cm^?1 and 0.044 μg cm^?2, respectively. The detection limits were 0.11 μg mL^?1 of ruthenium. The method is free from interferences from large number of cations and anions. Proposed method was successfully applied to the separation and determination of ruthenium from synthetic alloys, catalyst and water samples. Sequential separation and determination method for ruthenium(III), osmium(VIII) and iron(II) has been developed.