pH Of Donor Phase Research Articles

Multivariate optimization of the hollow fiber-based liquid phase microextraction of lead in human blood and urine samples using graphite furnace atomic absorption spectrometry

The present study developed a liquid-phase microextraction based on hollow fiber coupled with graphite furnace atomic absorption spectrometry for the effective extraction and quantitation of lead from urine and blood samples. A multivariate design was used for the optimization of the experimental conditions to ensure high extraction efficiency. Six factors (solvent type, chelating agent, time extraction, temperature, donor phase pH, and acceptor phase pH) were obtained by screening eleven factors of the Plackett–Burman design; these were optimized using the central composite design of response surface methodology. The optimum conditions of donor phase pH, acceptor phase pH, temperature, and extraction time were 5, 9.5, 40 °C, and 120 min, respectively. In addition, oleic acid containing dicyclohexyl-18-krone-6 was used for the membrane phase. Under optimal conditions, the enrichment factor, limit of detection, and limit of quantification were obtained in the ranges of 21.3–18.7, 0.001–0.002 ng mL−1, and 0.008–0.01 ng mL−1, respectively, in urine and blood samples. The linearity of the calibration curve was established for the concentration of Pb in the range of 1–50 ng mL−1 (r2 = 0.9983). Finally, the performance of the developed method was evaluated for the determination of lead in urine and blood samples, and satisfactory results were obtained (RSDs 95).

Prediction of rizatriptan trace level in biological samples: An application of the adaptive-network-based fuzzy inference system (ANFIS) in assisting drug dose monitoring

ABSTRACTIntroduction: Solvent bar microextraction technique is a sample preparation method prior to analysis for complicated matrices such as urine, blood, stem cell culture, and wastewater. This method, when coupled with adaptive-network-based fuzzy inference system, can detect and predict the concentration of trace elements and drugs at ultra-trace levels in complicated matrices.Material and method: Rizatriptan was used as a model drug for validation of this method. Therefore, six parameters (pH of donor and acceptor phase, stirring rate, time, temperature, and salt addition) affecting the preconcentration and determination of this drug were investigated. In this method, pH gradient was applied to transfer the drug into the solvent bar. MATLAB version 2010 was used for data analysis. Construction of an input-output mapping was done based on the results obtained from the experiments. For the simulation, the ANFIS architecture was employed to model nonlinear functions, identify nonlinear components in a control system, and predict a chaotic time series, all yielding remarkable results. Based on the best model chosen, the drug was preconcentrated and analyzed under the optimum condition.Results and discussion: The figures of merit were as follows: preconcentration factor: 127; limit of detection: 15 ng mL−1; limit of quantification: 50 ng mL−1; R2:0.999; RSD: 3.0%(interday) and 4.6% interaday. As a result, this method can be employed for preconcentration and microextraction of several elements, drugs, antibodies at trace levels in complicated matrices. After modeling, the optimum condition could be predicted without performing unnecessary and expensive experiments.Conclusion: Certain biomarkers can also be preconcentrated and detected using the proposed method. It offers high sample clean up, therefore it can be used for clean validation. Prediction of the course of treatment may be possible with the proposed method, therefore it is highly practical, easy and cost-effective.

Solvent-stir bar microextraction system using pure tris-(2-ethylhexyl) phosphate as supported liquid membrane: A new and efficient design for the extraction of malondialdehyde from biological fluids

A novel and efficient device of solvent stir-bar microextraction (SSBME) system coupled with GC-FID detection was introduced for the pre-concentration and determination of malondialdehyde (MDA) in different biological matrices. In the proposed device, a piece of porous hollow fiber was located on a magnetic rotor by using a stainless steel-wire (as a mechanical support) and the whole device could stir with the magnetic rotor in sample solution cell. The device provided higher pre-concentration factor and better precision in comparison with conventional SBME due to the reproducible, stable and high contact area between the stirred sample and the hollow fiber. Organic solvent type, donor and acceptor phase pH, temperature, electrolyte concentration, agitation speed, extraction time, and sample volume as the effective factors on the SSBME efficiency, were examined and optimized. Pure tris-(2-ethylhexyl) phosphate (TEHP) was examined for the first time as supported liquid membrane (SLM) for the determination of MDA by SSBME method. In contrast to the conventional SLMs of SBME in the literature, the SLM of TEHP was highly stable in contact with biological fluids and provided the highest extraction efficiency. Under optimized extraction conditions, the method provided satisfactory linearity in the range 1–500 ng mL−1, low LODs (0.3–0.7 ng mL−1), good repeatability and reproducibility (RSD% (n = 5) < 4.5) with the pre-concentration factors higher than 130-fold. To verify the accuracy of the proposed method, the traditional spectrophotometric TBA (2-thiobarbituric acid) test was used as a reference method. Finally, the proposed method was successfully applied for the determination and quantification of MDA in biological fluids.

In situ derivatization and hollow-fiber liquid-phase microextraction to determine sulfonamides in water using UHPLC with fluorescence detection.

A sensitive method for determining sulfonamides in water was developed and validated through in situ derivatization and hollow-fiber liquid-phase microextraction with ultra-high performance liquid chromatography and fluorescence detection. The target sulfonamides were sulfadiazine, sulfacetamide, sulfamerazine, sulfamethazine, sulfamethoxypyridazine, sulfachloropyridazine, sulfamethoxazole, and sulfisoxazole. Following in situ derivatization with fluorescamine, three-phase hollow-fiber liquid-phase microextraction with an S 6/2 polypropylene hollow-fiber membrane was applied automatically using a multipurpose autosampler. Experimental parameters including derivatization time, choice of organic phase, pH of donor and acceptor phase, stirring rate, extraction temperature and time were optimized. Under optimized conditions, the target sulfonamides achieved excellent linearity with correlation coefficients of 0.9924-0.9994 within the concentration range of 0.05-5μg/L. The limits of detection of the eight sulfonamides were 3.1-11.2ng/L, and the limits of quantification were 10.3-37.3ng/L. Enrichment factors of 0.1 and 5μg/L sulfonamides spiked in lake water were 14-60, and recoveries were 56-113% with relative standard derivations of 3-19%. Applied with the developed method, sulfamerazine and sulfamethoxazole were measurable in both influent and effluent water of the three sewage treatment plants in Guangzhou, China. The developed method was sensitive and provided an alternative method for simultaneously enriching and quantifying multiple sulfonamides in environmental water.

Zero valent Fe-reduced graphene oxide quantum dots as a novel magnetic dispersive solid phase microextraction sorbent for extraction of organophosphorus pesticides in real water and fruit juice samples prior to analysis by gas chromatography-mass spectrometry.

A selective and sensitive magnetic dispersive solid-phase microextraction (MDSPME) coupled with gas chromatography-mass spectrometry was developed for extraction and determination of organophosphorus pesticides (Sevin, Fenitrothion, Malathion, Parathion, and Diazinon) in fruit juice and real water samples. Zero valent Fe-reduced graphene oxide quantum dots (rGOQDs@ Fe) as a new and effective sorbent were prepared and applied for extraction of organophosphorus pesticides using MDSPME method. In order to study the performance of this new sorbent, the ability of rGOQDs@ Fe was compared with graphene oxide and magnetic graphene oxide nanocomposite by recovery experiments of the organophosphorus pesticides. Several affecting parameters in the microextraction procedure, including pH of donor phase, donor phase volume, stirring rate, extraction time, and desorption conditions such as the type and volume of solvents and desorption time were thoroughly investigated and optimized. Under the optimal conditions, the method showed a wide linear dynamic range with R-square between 0.9959 and 0.9991. The limit of detections, the intraday and interday relative standard deviations (n = 5) were less than 0.07 ngmL-1, 4.7, and 8.6%, respectively. The method was successfully applied for extraction and determination of organophosphorus pesticides in real water samples (well, river and tap water) and fruit juice samples (apple and grape juice). The obtained relative recoveries were in the range of 82.9%-113.2% with RSD percentages of less than 5.8% for all the real samples.

Extraction, preconcentration, and determination of methylphenidate in urine sample using solvent bar microextraction in combination with HPLC–UV: Optimization by experimental design

ABSTRACTMethylphenidate (Ritalin) is a drug used for attention-deficit hyperactivity disorder treatment and narcolepsy symptoms control. This drug inhibits norepinephrine and dopamine reuptake in presynaptic neuron and appears to stimulate the cerebral cortex and subcortical structures similar to amphetamines. The aim of this work is to develop a new method for extraction, preconcentration, and determination of methylphenidate in human urine samples using solvent bar microextraction combined with HPLC and optimization by design of experiment approach. To get to the highest preconcentration factor, the effect of various affecting parameters such as the type of extraction solvent, donor phase pH, receiving phase pH, salt addition to the acceptor phase, extraction time, stirring speed, and extraction temperature was investigated and optimized by design of experiment approach. Under the optimized condition extraction (solvent: n-octanol, donor phase pH: 11.6; acceptor phase pH: 4; stirring speed: 650 rpm; extraction time: 25 min; temperature: 25°C; salt concentration in donor phase: 30% w/v NaCl), the following results were achieved: preconcentration factor: 104, limit of detection: 15 ng/mL, intra-day RSD: 3.5%, and inter-day RSD: 3.9%. Finally, the feasibility of this extraction method was confirmed by analyzing urine sample and satisfactory results were obtained.

Rapid removal of uranium from aqueous solution by emulsion liquid membrane containing thenoyltrifluoroacetone

In this study, the removal of uranium from aqueous solution is studied using emulsion liquid membrane (ELM) system. The ELM is made up of 2-Thenoyltrifluoroacetone (HTTA) as a carrier, kerosene as an organic diluent, HCl as a stripping solution and sorbitan monooleate (Span-80) as a surfactant for stabilizing the emulsion phase. Initially, the important parameters affecting the removal of uranium, were screened out using a fractional factorial design. Then the effect of the selected factors were studied to obtain the optimal conditions. Under the assessed conditions (pH of donor phase=5; HTTA concentration in the membrane phase=0.02mol/L; emulsion/donor phase volume ratio=0.2; uranium concentration in the donor phase <150mg/L), the removal percentage of uranium was obtained 99.8% in less than five minutes.

Switchable-hydrophilicity solvent-based microextraction combined with gas chromatography for the determination of nitroaromatic compounds in water samples.

A simple, fast, sensitive, and low-cost method was developed for the quantification of nitroaromatic compounds in water samples based on CO2 -assisted liquid-phase microextraction using a switchable-hydrophilicity solvent followed by gas chromatography detection. Dipropylamine was used as extraction solvent with switchable hydrophilicity that can be miscible or immiscible upon the addition or removal of CO2 as a reagent. Experimental parameters affecting the extraction efficiency such as the volume of acceptor phase, the volume of donor phase, pH of donor phase, ionic strength, and extraction time were investigated. Under the optimal conditions, detection limits and preconcentration factors were obtained in the ranges of 0.9-1.8μg/L and 132-138, respectively. Also, the extraction recoveries of water samples were above 88%. Finally, the developed method was successfully applied to the determination of nitroaromatic compounds in real water samples.

Introduction of Fullerene as a New Carrier in Electromembrane Extraction for the Determination of Ibuprofen and Sodium Diclofenac as Model Acidic Drugs in Real Urine Samples

Introducing new additives in supported liquid membrane (SLM) as carriers is an interesting and debatable issue in the field of microextraction methods, especially in electro membrane extraction (EME). In this study, C60 fullerene was used as a new carrier in the SLM, and EME followed by high-performance liquid chromatography coupled with ultraviolet detection was optimized and validated for the quantification of ibuprofen and sodium diclofenac as two model acidic drugs. Optimized conditions for extraction of the mentioned drugs from 4.0 mL aqueous sample were obtained as follows: 1-octanol containing 0.6% (w/v) C60 fullerene as the SLM, potential difference of 6 V, 28 min as the extraction time, 12.8 as the acceptor phase pH value and 10.5 as the donor phase pH value. Under the optimized conditions, the enrichment factors were obtained within the range of 166–188, which corresponds to extraction recoveries of 83–94%. The limits of detection and quantification were in the range of 5–10 and 15–30 ng mL−1, respectively. To understand the influence of C60 fullerene on extraction efficiency, a comparative study was carried out between conventional EME and modified EME methods. The results showed that the presence of C60 fullerene in the SLM increased the overall analyte partition coefficient in the membrane and, therefore, led to an enhancement in analyte transport. Finally, the applicability of this method was evaluated by the extraction and determination of these drugs in real urine samples.

Electrospray Ionization-Ion Mobility Spectrometry in the Negative Mode Combined with Hollow Fiber Liquid–Liquid–Liquid Microextraction for the Determination of Diclofenac in Urine and Plasma Samples

The combination of hollow fiber liquid–liquid–liquid microextraction and electrospray ionization-ion mobility spectrometry (ESI-IMS) was used for the analysis of diclofenac in biological samples. Diclofenac was extracted from an acidic aqueous sample into methanol as an acceptor phase, through n-dodecane impregnated in the hollow fiber pores. The extracted drug was detected with ESI-IMS in the negative mode. Extraction parameters including pH of donor phase, stirring rate, sample ionic strength, temperature and extraction time were studied. The linearity of the method for the determination of diclofenac was in the range of 100–2000 and 60–2000 µg L−1 for plasma and urine, respectively. The detection limit of the method was also 34 and 21 µg L−1 in the plasma and urine, respectively. The applicability of the method for analyzing the analyte in biological samples was investigated. The method was also applied to analysis of urine and plasma of a healthy volunteer after oral administration of diclofenac.

Preconcentration and spectrophotometric determination of trace amount of formaldehyde using hollow fiber liquid-phase microextraction based on derivatization by Hantzsch reaction

Formaldehyde is known as a highly toxic compound to humans and identified as a carcinogenic substance. In this study, Hantzsch reaction was utilized for the derivatization of trace amounts of formaldehyde in aqueous samples with acetylacetone in the presence of ammonia to form an extractable colored product named 3,5-diacetyl 1,4-dihydrolutidine (DDL) and its further extraction using two-phase hollow fiber liquid-phase microextraction. The main experimental variables affecting the extraction performance were investigated and optimized. Under the optimum conditions (sample volume 12 mL; reaction temperature 70 °C; ammonium acetate buffer solution 4 mL 0.1 mol L−1; acetylacetone 5 mL 0.15 mol L−1; solvent octanol, salt concentration 20% (w/v) NaCl; pH of donor phase 7.0; stirring speed 400 rpm and extraction time 30 min), the linear dynamic range, limit of detection (LOD as 3Sb/m) and relative standard deviation (RSD %) of the proposed method were obtained as 5–250 μg L−1 (r2 = 0.9979), 3.6 μg L−1 and 2.5%, respectively. Finally, the applicability of the proposed method was examined, and very good results were obtained. The results confirmed the applicability of the proposed method as a versatile, low-cost and sensitive preconcentration method for determination of low concentrations of formaldehyde in aqueous solutions.

The kinetic analysis of optimization and selective transportation of Cu(II) ions with TNOA as carrier by MDLM system

This study covers the transportation of Cu(II) ions by multi-dropped liquid membrane (MDLM) system and tri-n-octylamine (TNOA) as carrier in kerosene. Batch experiments are held to obtain optimum conditions for the transportation of Cu(II) ions such as volume of donor, organic, and acceptor phase 100ml, pH of donor phase 9.00, temperature 298.15K, concentration of H2SO4 in acceptor phase 1.00mol·L−1, concentration of TNOA in organic phase 5.00×10−3mol·L−1 and rate of peristaltic pump 50ml·min−1. Optimum circumstances of this extraction are as follows: pH of donor phase is 9.00, concentration of TNOA is 5.00×10−3mol·L−1, 1.00mol·L−1 H2SO4 as acceptor phase, and flux rate is 50ml·min−1. Cu(II) ion transportation is consecutive first order irreversible reaction. Activation energy is found as 5.22kcal·mol−1 (21.82kJ·mol−1), this process is called as diffusion controlled system. Selective transportation of Cu(II) ions with alkaline, alkaline earth, and different heavy metal ions at optimum conditions of single Cu(II) extraction was conducted. According to the selective transportation Cu(II) ions with alkaline and alkaline earth metal ions, Na+, K+, and Ba2+ ions are not detected in the acceptor phase, but 12.00% of Ca2+ ions is transported from donor phase to acceptor phase. At the end of the simultaneous extraction of Zn(II), Fe(III), and Mo(VI) with Cu(II) ions, 2.20% of Mo(VI), 0.80% of Fe(III) and 3.60% of Zn(II) are detected in the acceptor phase.

Multivariate optimization of the hollow fibre liquid phase microextraction of muscimol in human urine samples.

A liquid phase microextraction based on hollow fibre followed by liquid chromatographic determination was developed for the extraction and quantitation of the hallucinogenic muscimol from urine samples. Method applicability on polar hallucinogens was also tested on two alkaloids, a psychedelic hallucinogen, tryptamine and a polar amino acid, tryptophan which exists in its charged state in the entire pH range. A multivariate design of experiments was used in which a half fractional factorial approach was applied to screen six factors (donor phase pH, acceptor phase HCl concentration, carrier composition, stirring rate, extraction time and salt content) for their extent of vitality in carrier mediated liquid microextractions. Four factors were deemed essential for the effective extraction of each analyte. The vital factors were further optimized for the extraction of single-spiked analyte solutions using a central composite design. When the simultaneous extraction of analytes was performed under universal factor conditions biased towards maximizing the enrichment of muscimol, a good composite desirability value of 0.687 was obtained. The method was finally applied on spiked urine samples with acceptable enrichments of 4.1, 19.7 and 24.1 obtained for muscimol, tryptophan and tryptamine respectively. Matrix-based calibration curves were used to address matrix effects. The r(2) values of the matrix-based linear regression prediction models ranged from 0.9933 to 0.9986. The linearity of the regression line of the matrix-based calibration curves for each analyte was directly linked to the analyte enrichment repeatability which ranged from an RSD value of 8.3-13.1%. Limits of detection for the developed method were 5.12, 3.10 and 0.21ngmL(-1) for muscimol, tryptophan and tryptamine respectively. The developed method has proven to offer a viable alternative for the quantitation of muscimol in human urine samples.

A glass capillary based microfluidic electromembrane extraction of basic degradation products of nitrogen mustard and VX from water

In this work, a glass capillary based microfluidic electromembrane extraction (μ-EME) was demonstrated for the first time. The device was made by connecting an auxillary borosilicate glass tubing (O.D. 3mm, I.D. 2mm) perpendicular to main borosilicate glass capillary just below one end of the capillary (O.D. 8mm, I.D. 1.2mm). It generated the distorted T-shaped device with inlet ‘1’ and inlet ‘2’ for the introduction of sample and acceptor solutions, respectively. At one end of this device (inlet ‘2’), a microsyringe containing acceptor solution along with hollow fiber (O.D. 1000μm) was introduced. This configuration creates the micro-channel between inner wall of glass capillary and outer surface of hollow fiber. Sample solution was pumped into the system through another end of glass capillary (inlet ‘1’), with a micro-syringe pump. The sample was in direct contact with the supported liquid membrane (SLM), consisted of 20% (w/w) di-(2-ethylhexyl)phosphate in 2-nitrophenyl octyl ether immobilized in the pores of the hollow fiber. In the lumen of the hollow fiber, the acceptor phase was present. The driving force for extraction was direct current (DC) electrical potential sustained over the SLM. Highly polar (logP=−2.5 to 1.4) basic degradation products of nitrogen mustard and VX were selected as model analytes. The influence of chemical composition of SLM, extraction time, voltage and pH of donor and acceptor phase were investigated. The model analytes were extracted from 10μL of pure water with recoveries ranging from 15.7 to 99.7% just after 3min of operation time. Under optimized conditions, good limits of detection (2–50ngmL−1), linearity (from 5–1000 to 100–1000ngmL−1), and repeatability (RSDs below 11.9%, n=3) were achieved. Applicability of the proposed μ-EME was proved by recovering triethanolamine (31.3%) from 10μL of five times diluted original water sample provided by the Organization for the Prohibition of Chemical Weapons during 28th official proficiency test.

Application of hollow fiber membrane mediated with titanium dioxide nanowire/reduced graphene oxide nanocomposite in preconcentration of clotrimazole and tylosin

In this paper, TiO2 nanowires and TiO2 nanoparticles have been successfully anchored on graphene oxide (GO) nanosheets by a facile one-step hydrothermal method. The synthesized TiO2 NWs/RGO and TiO2 NPs/RGO nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. After comparatively studying of the as-made nanocomposites, TiO2 NWs/RGO nanocomposite showed the best adsorbing performance and applied as an attractive efficient sorbent reinforced with microporous hollow fiber membrane through the sol–gel technology. In the following, the selected nanocomposite was utilized for simultaneous preconcentration and determination of clotrimazole and tylosin using high performance liquid chromatography (HPLC)–UV detection, respectively. In order to optimize the extraction conditions through affecting parameters (pH, stirring rate, salt addition, extraction time and volume of donor phase), response surface methodology (RSM) was employed as a powerful statistical technique. Under the optimal conditions, the limit of detection (S/N=3) of proposed HFSPME method, was 0.67μgL−1 for clotrimazole and 0.91μgL−1 for tylosin with good linear ranges of 1.7–8000.0μgL−1 and 4.0–6000.0μgL−1. The inter-day and intra-day relative standard deviations (RSD%) at 100μgL−1 concentration level were in the ranges of 2.10–3.58% for clotrimazole and 3.45–7.80% for tylosin (n=5), respectively. The proposed microextraction device was extended for determination of ultra trace amounts of target analytes in milk and urine samples with satisfactory results.

Three-phase hollow-fiber microextraction combined with ion-pair high-performance liquid chromatography for the simultaneous determination of five components of compound α-ketoacid tablets in human urine.

The determination of α-ketoacid concentration is demanded to evaluate the absorption and metabolic behavior of compound α-ketoacid tablets taken by chronic kidney disease patients. To eliminate the interference of endogenous substance of urine and enrich the analytes, a three-phase hollow-fiber liquid-phase microextraction combined with ion-pair high-performance liquid chromatography method was established for the determination of d,l-α-hydroxymethionine calcium, d,l-α-ketoisoleucine calcium, α-ketovaline calcium, α-ketoleucine calcium, and α-ketophenylalanine calcium of compound α-ketoacid tablets in human urine samples. The extraction parameters, such as organic solvent, pH of donor phase and acceptor phase, stirring rate, and extraction time were optimized. Under the optimal conditions, the obtained enrichment factors were up to 11-, 110-, 198-, 202-, and 50-fold, respectively. The calibration curves for these analytes were linear over the range of 0.1-10 mg/L for α-ketovaline calcium, d,l-α-ketoisoleucine calcium, and α-ketoleucine calcium, 0.5-10 mg/L for d,l-α-hydroxymethionine calcium, and α-ketophenylalanine calcium with r > 0.99. The relative standard deviations (n = 5) were less than 6.27% and the LODs were 100.7, 10.0, 5.8, 7.8, and 8.6 μg/L (based on S/N = 3), respectively. Good recoveries from spiked urine samples (92-118%) were obtained. The proposed method demonstrated excellent sample clean-up and analytes enrichment to determine the five components in human urine.

Transportation and kinetic analysis of Mo(VI) ions through a MDLM system containing TNOA as carrier

In this report, Mo(VI) ions are transported from an aqueous donor phase into an aqueous acceptor phase by a newly designed method called as multi dropped liquid membrane (MDLM) system prepared by dissolving TNOA as carrier in kerosene. During the extraction of Mo(VI) ions by the liquid membrane system; 100ppm Mo(VI) solutions as donor phase, buffer solution(pH:9.5) and Na2CO3 in different concentrations as acceptor phase and TNOA diluted by kerosen as organic phase are used.In our experimental work, the effect of temperature by using buffer solution and Na2CO3 in the acceptor phase and effect of concentration of acceptor phase on the extraction of Mo(VI) ions were investigated.Appropriate conditions for Mo(VI) transportation were as follows: pH of donor phase is 2.00, concentration of TNOA is 0.005M, 1.00M Na2CO3 as acceptor phase, and flux rate is 50mL/min. Besides, Mo(VI) ion transportation is consecutive first order irreversible reaction and the transportation of Mo(VI) ions is diffusion controlled process. The kinetic parameters (k1, k2, Rmmax, tmax, Jdmax, Jamax) were calculated for the interface reactions assuming two consecutive, irreversible first-order reactions.

Selective transport of copper (II) from zinc (II), lead (II), cadmium (II), nickel (II), and cobalt (II) ions mixture through bulk liquid membrane using 5-nitro-8-quinolinol as a carrier

The transport of Cu2+ ion through a chloroform (CHCl3) bulk liquid membrane containing 5-nitro-8-quinolinol (NQ) as a selective carrier was studied. The NQ is an efficient carrier for the transport of Cu2+ from aqueous solutions containing equimolar concentration of other cations such as Cd2+, Pb2+, Zn2+, Ni2+, and Co2+ ions. The parameters that have influence on the transport efficiency such as transport time, type, and concentration of stripping agent in acceptor phase, concentration of NQ in membrane phase, pH of donor phase, and stirring rate were examined. Under optimum conditions, the extent of Cu2+ transports across the liquid membrane was about 33.05% after 24 h and cation fluxes (JM) were studied for the transport of Cu2+ in different membranes, and the maximum amount of JM was 9.58 × 10−9 (mol/m2s) in CHCl3. The applicability of the method was examined for the separation of copper (II) ions from real liquid samples. Transport efficiency of Cu2+ for three replicate measurements in river liquid samples RW1, RW2, and RW3 obtained 29.9 ± 2.2%, 32.0 ± 1.5%, and 30.3 ± 2.1%, respectively, after 24 h.

Determination of tramadol by dispersive liquid-liquid microextraction combined with GC-MS.

Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) has been developed for preconcentration and determination of tramadol, ((±)-cis-2-[(dimethylamino)methyl]-1-(3-methoxyphenyl)cyclohexanol-HCl), in aqueous and biological samples (urine, blood). DLLME is a simple, rapid and efficient method for determination of drugs in aqueous samples. Efficient factors on the DLLME process has defined and optimized for extraction of tramadol including type of extraction and disperser solvents and their volumes, pH of donor phase, time of extraction and ionic strength of donor phase. Based on the results of this study, under optimal conditions and by using 2-nitro phenol as internal standard, tramadol was determined by GC-MS, and the figures of merit of this work were evaluated. The enrichment factor, relative recovery and limit of detection were obtained 420, 99.2% and 0.08 µg L(-1), respectively. The linear range was between 0.26 and 220.00 µg L(-1) (R(2) = 0.9970). The relative standard deviation for 50.00 µg L(-1) of tramadol in aqueous samples by using 2-nitro phenol as IS was 3.6% (n = 7). Finally, the performance of DLLME was evaluated for analysis of tramadol in urine and blood.

Hollow fiber supported ionic liquid membrane microextraction for preconcentration of kanamycin sulfate with electrochemiluminescence detection

Three-phase hollow fiber based liquid phase microextraction (HF-LPME) was developed for the preconcentration of kanamycin sulfate combined with electrochemiluminescence detection. The extractant was 1-octyl-methylmidazolium hexafluorophosphate ([OMIM]PF6). A hollow fiber supported liquid membrane was used between phosphate buffer solution (PBS) containing analyte (kanamycin sulfate) as donor phase and aqueous solution (pH 10) as acceptor phase. The effects of various parameters on the extraction efficiency were studied, such as pH of ECL working solution, extraction temperature, pH of donor phase, extraction time and salt content of sample. Under the optimized conditions, the linear range was 0.002–0.1μgmL−1, and the limit of detection (LOD) was 0.00067μgmL−1. No expensive equipment is necessary to perform this assay which makes it a viable replacement.