mL Of Sample Solution Research Articles

Electrically enhanced microextraction for highly selective transport of three β-blocker drugs

Facilitated transport of three β-blocker drugs including atenolol (ATE), betaxolol (BET) and propranolol (PRO) was investigated under electrical field across a supported liquid membrane (SLM) using phosphoric acid derivatives as selective ion carriers, dissolved in 2-nitro phenyl octyl ether (NPOE). In the presence of di-(2-ethylhexyl) phosphate (DEHP) and tris-(2-ethylhexyl) phosphate (TEHP) in the membrane phase, the three β-blockers showed completely different transport behaviors which enabled highly selective separation of the drugs. Each β-blocker migrated from 3 mL of sample solutions, through a thin layer of specific organic solvent immobilized in the pores of a porous hollow fiber, and into a 15 μL acidic aqueous acceptor solution present inside the lumen of the fiber. The influences of fundamental parameters affecting the transport of target drugs including type of ion carrier for selective separation of each drug and its concentration in the membrane phase, extraction voltage, time of transport, pH of donor and acceptor phases, stirring speed of donor phase and salt effect were studied and optimized. After microextraction process, the extracts were analyzed by high-performance liquid chromatography with ultraviolet detection. Under optimal conditions, ATE was selectively extracted from different saliva samples with recovery of 37%, which corresponded to preconcentration factor of 74. A good linearity was achieved for calibration curve with a coefficient of determination higher than 0.997. Limits of detection and intra-day precision ( n = 3) were less than 2 μg L −1 and 8.8%, respectively.

Determination of thebaine in water samples, biological fluids, poppy capsule, and narcotic drugs, using electromembrane extraction followed by high-performance liquid chromatography analysis

Opium determination is of great importance from toxicological and pharmaceutical standpoints. In present work, electromembrane extraction (EME) coupled with high-performance liquid chromatography (HPLC) and ultraviolet (UV) detection was developed for determination of thebaine as a natural alkaloid, in different matrices containing water, urine, poppy capsule, street heroine, and codeine tablet. Thebaine migrated from 3 mL of sample solutions, through a thin layer of 2-nitrophenyl octyl ether (NPOE) immobilized in the pores of a porous hollow fiber, and into a 15 μL acidic aqueous acceptor solution present inside the lumen of the fiber. The variables of interest, such as chemical composition of the organic liquid membrane, stirring speed, extraction time and voltage, pH of donor and acceptor phases and salt effect in the EME process were optimized. Under optimal conditions, thebaine was effectively extracted from different matrices with recoveries in the range of 45–55%, which corresponded to preconcentration factors in the range of 90–110. Good linearity was achieved for calibration curves with a coefficient of estimation higher than 0.997. Detection limits and intra-day precision ( n = 3) were less than 15 μg L −1 and 8.9%, respectively.

Hollow fiber‐based liquid–liquid–liquid microextraction followed by flow injection analysis using column‐less HPLC for the determination of phenazopyridine in plasma and urine

Hollow fiber-based liquid-liquid-liquid microextraction (HF-LLLME) followed by flow injection analysis and diode array detection (FIA-DAD) was applied as a simple and sensitive quantitative method for the determination of phenazopyridine in urine and plasma samples. Flow injection system included a conventional HPLC system (without a chromatographic column) and a diode array detector. The extraction of phenazopyridine was carried out using diphenyl ether as the organic phase for filling the pores of the hollow fiber wall, and 0.1 M H(2)SO(4) solution as acceptor phase in the lumen of the fiber. The factors affecting the HF-LLLME and flow injection analysis including type of organic solvent, pH of donor phase, extraction temperature, extraction time, stirring rate, and pH of mobile phase were investigated and the optimal extraction conditions were established. With the consumption of 5 mL of sample solution, the enrichment factor was about 230. The limit of detection was 0.5 μg/L with inter- and intra-day precision being (RSD%) 6.9 and 4.9, respectively. Excellent linearity was found between 5 and 200 μg/L.

Determination of silver(I) by flame atomic absorption spectrometry after separation/preconcentration using modified magnetite nanoparticles

A new, simple, fast and reliable method has been developed for the separation/preconcentration of trace amounts of silver ions using 2-mercaptobenzothiazole/sodium dodecyl sulfate immobilized on alumina-coated magnetite nanoparticles (MBT/SDS-ACMNPs) and their determination by flame atomic absorption spectrometry (FAAS). Optimal experimental conditions, including pH, sample volume, eluent concentration and volume, and co-existing ions, have been studied and established. Under optimal experimental conditions, the enrichment factor, detection limit, linear range and relative standard deviation (RSD) of Ag(I) ions were 250 (for 500 mL of sample solution), 0.56 ng mL−1, 2.0–100.0 ng mL−1 and 3.1% (for 5.0 μg mL−1, n=10), respectively. The presented procedure was successfully applied for determination of silver content in the different samples of water.

Evaluation of selenium in biological sample of arsenic exposed female skin lesions and skin cancer patients with related to non-exposed skin cancer patients

The antagonistic effects between selenium (Se) and arsenic (As) suggest that low Se status plays an important role in arsenism development. The objective of present study was to assess Se contents in biological samples of As exposed females have skin lesions and cancer with related to non-exposed skin cancer patients. The biological samples (blood and scalp hair) of As exposed group comprises, female skin cancer (ESC) patients admitted in cancer hospitals have skin lesions (ESL) and exposed referents have not both diseases (ER), belongs to As exposed area of Pakistan. For comparative purposes, age matched female skin cancerous patient (RP) and non-cancerous females (NER) belong to non-exposed areas were also selected. The As and Se in acid digests of biological samples were pre-concentrated by complexing with chelating agent (ammonium pyrrolidinedithiocarbamate), and resulted complexes were extracted into non-ionic extractant (Triton X-114), prior to analysis by electrothermal atomic absorption spectrometry. The enhancement factor of about 25 was obtained by pre-concentrating 10 mL of sample solutions. The accuracy of the optimized procedure was evaluated by using certified reference material (BCR 397) with certified values for Se and As and standard addition method at three concentration levels in real samples. No significant differences was observed (p > 0.05) when comparing the values obtained by the proposed method, added and certified values of both elements. The biological samples of ESC patients had 2–3 folds higher As and lower Se levels as compared to RP (p < 0.001). Understudied exposed referents have high level of As and lower Se contents as compared to referents subjects of non-exposed area (p < 0.01). The higher concentration of As and lower levels of Se in biological samples of cancerous patients are consisted with reported studies.

Dithizone immobilized silica gel on-line preconcentration of trace copper with detection by flame atomic absorption spectrometry

A novel adsorbent-silica gel bound dithizone (H2Dz-SG) was prepared and used as solid-phase extraction of copper from complex matrix. The H2Dz-SG is investigated by means of FT-IR spectra and the SEM images, demonstrating the bonding of dithizone. The H2Dz-SG quantitatively adsorb copper ions, and the retained copper is afterwards collected by elution of 10% (v/v) nitric acid. An on-line flow injection solid-phase extraction procedure was developed for trace copper separation and preconcentration with detection by flame atomic spectrometry. By loading 5.4mL of sample solution, a liner range of 0.5–120μgL−1, an enrichment factor of 42.6, a detection limit of 0.2μgL−1 and a precision of 1.7% RSD at the 40μgL−1 level (n=11) were obtained, along with a sampling frequency of 47h−1. The dynamic sorption capacity of H2Dz-SG to Cu2+ was 0.76mgg−1. The accuracy of the proposed procedure was evaluated by determination of copper in reference water sample. The potential applications of the procedure for extraction of trace copper were successfully accomplished in water samples (tap, rain, snow, sea and river). The spiking recoveries within 91–107% are achieved.

Determination of copper traces in water samples by flow injection-flame atomic absorption spectrometry using a novel solidified floating organic drop microextraction method

A simple, rapid and inexpensive solidified floating organic drop microextraction (SFODME) and flow injection flame atomic absorption spectrometric determination (FI-FAAS) method for copper were developed. 3-amino-7-dimethylamino-2-methylphenazine (Neutral red, NR) was used as the complexing agent. Several factors affecting the microextraction efficiency, such as, pH, NR and sodium dodecylbenzenesulfonate (SDBS) concentration, extraction time, stirring rate, and temperature were investigated and optimized. Under optimized experimental conditions an enrichment factor of 541 was obtained for 100 mL of sample solution. The calibration graph was linear in the range of 0.5–20.0 ng mL − 1 and the limit of detection (3 s) was 0.18 ng mL − 1 , the limit of quantification (10 s) was 0.58 ng mL − 1 . The relative standard deviation (RSD) for 10 replicate measurements of 10 ng mL − 1 copper was 2.7%. The developed method was successfully applied to the extraction and determination of copper in different certified reference materials (Estuarine water, Slew 3 and fortified water, TM 23.2) and real water samples and satisfactory results were obtained.

Preconcentration of Lead in Sugar Samples by Solid Phase Extraction and Its Determination by Flame Atomic Absorption Spectrometry

A simple and sensitive solid phase extraction utilizing C18 filled cartridges incorporated with dithizone for preconcentration of lead and its subsequent determination by flame atomic absorption spectrometry (FAAS) was developed. Several parameters such as type, concentration and volume of eluent, pH of the sample solution, flow rate of extraction and volume of the sample were evaluated. The effect of a variety of ions on preconcentration and recovery was also investigated. At pH = 7.4 and 1.0 mol?L–1 HCl eluting them, lead ions were recovered quantitatively. The limit of detection (LOD) defined as 3Sbl was determined to be 8.1 μg L–1 for 500 mL of sample solution and eluted with 5 mL of 1.0 mol?L–1 HCl under optimum conditions. The accuracy and precision (RSD %) of the method were >90% and <10%, respectively. In the end, the proposed method was applied to a number of real sugar samples and the amount of lead was determined by spiking a known concentration of lead into the solution.

Solid-Phase Extraction Clean-up Combined with Solidified Floating Organic Drop Microextraction for the Determination of Trace Manganese(II) in Different Environmental Matrices

Solid-phase extraction (SPE) clean-up combined with solidified floating organic drop microextraction (SFODME) has been developed as a new approach for the extraction and determination of trace manganese(II) in environmental water and vegetable samples. After purification of the samples by a graphene-packed SPE cartridge, SFODME technique was performed on the obtained solution. The main parameters affecting the performance of SFODME, such as type of extraction solvent as well as extraction volume, time, temperature, pH, the amount of the chelating agent, and salt effect were investigated and optimized. Under optimum conditions, a preconcentration factor of 81.0 was obtained from 7.0 mL of sample solution. The calibration graph was linear in the range from 1.90 to 400 μg/L with a detection limit of 0.57 μg/L. The relative standard deviation for ten replicate measurements of 10 and 300 μg/L of manganese(II) were 3.57 and 2.63 %, respectively. The proposed method was applied to tap, sea, river, and vegetable samples, and its accuracy was assessed through the analysis of certified reference water and recovery experiments.

An online ionic liquid-based microextraction system coupled to electrothermal atomic absorption spectrometry for determination in environmental samples and pharmaceutical formulations.

In the present work, an ionic liquid (IL) lighter than water was employed as extraction solvent in a dispersive liquid-liquid microextraction (DLLME) methodology. An original flow injection system for online microextraction and preconcentration of cobalt (Co) based on the use of tetradecyl(trihexyl)phosphonium chloride (CYPHOS® IL 101) was designed. Cobalt was complexed with 4-(2-pyridylazo)-resorcinol (PAR) reagent at pH 4.8 and then, the IL-DLLME procedure was developed by dispersing CYPHOS® IL 101 with acetone in an aqueous solution containing Co-PAR complex. Different pyridylazo dyes were evaluated for Co preconcentration in terms of their molecular structure, stability and acid-base equilibrium. Online extraction of Co-PAR into the IL and separation of the dispersed IL enriched phase were accomplished with a microcolumn containing Florisil material. Cobalt was removed from the microcolumn with a 10% (v/v) HNO3 acidified-acetone solution and finally measured by electrothermal atomic absorption spectrometry (ETAAS). The detection limit achieved after preconcentration of 2 mL of sample solution was 8 ng L-1. The precision for 10 replicate determinations at the 1 µg L-1 Co level was 5.1% relative standard deviation (RSD), calculated from the peak heights obtained. The method was successfully applied to Co determination in water samples as well as ophthalmic and parenteral solutions. For the first time, an IL-based microextraction technique was applied for metal determination in these complex samples, where Co recovery varied between 97.9 and 103%.

Magnetic quantitative immunoanalysis of carcinoembryonic antigen by ICP-MS with mercury labels

The need of analytical methods for absolute quantitative protein analysis spurred research on new developments in recent years. In this paper, a sensitive and selective method based on mercury labeled magnetic immunoassay and inductively coupled plasma mass spectrometry (ICP-MS) detection was proposed for the quantification of carcinoembryonic antigen (CEA) in real human serum samples. Size exclusion chromatography (SEC) combined with ICP-MS was applied for the separation and detection of secondary antibody labeled with mercury and excess mercury. After a complete sandwich-type immunoreaction among primary antibody, CEA and secondary antibody labeled with mercury on magnetic nanoparticles (MNPs), the concentration of CEA was determined by microconcentric nebulizer (MCN)-ICP-MS analysis of mercury ion released from secondary antibody with an acid-dissolution (pH 1.0) step. With consumption of only 50 μL sample solution, the established method presented a limit of detection of 0.041 ng mL−1 for CEA, with the relative standard deviation (RSD) of 5.2% (c = 8 ng mL−1, n = 7). The response for CEA was linear over a dynamic range from 0.1 to 50 ng mL−1. The analytical results of CEA in three different human serum samples obtained by the proposed method are in good agreement with that obtained by the commonly used clinical method of chemiluminescent immunoassay (CLIA). The developed method was versatile and could be easily extended to other proteins quantitative analysis, especially for specific biomarker determination.

Nanoparticle labelling-based magnetic immunoassay on chip combined with electrothermal vaporization - inductively coupled plasma mass spectrometry for the determination of carcinoembryonic antigen in human serum

A sensitive and selective on chip magnetic immunoassay method, based on a sandwich-type immunoreaction with PbS nanoparticle (NPs) labels in combination with electrothermal vaporization-inductively coupled plasma mass spectrometry (ETV-ICP-MS), was proposed for the determination of carcinoembryonic antigen (CEA). We designed and fabricated a microfluidic chip for magnetic immunoassay, and the prepared iminodiacetic acid modified silica coated magnetic nanoparticles (IDA-SCMNPs) were packed into the central microchannel to form a solid phase column by self-assembly under the magnetic field. After completion of the immunoreaction involving a primary antibody, CEA and a secondary antibody labeled with PbS NPs on a magnetic solid phase packed-column, ETV-ICP-MS was used to determine the concentration of Pb that was released from the captured PbS NPs using an acid-dissolution step. The concentrations of CEA can be correlated with that of Pb. The established method demonstrated a limit of detection of 0.058 μg L(-1) for CEA, with a relative standard deviation (RSD) of 6.7% (c = 10 μg L(-1), n = 7). A linearity ranging from 0.2 μg L(-1) to 50 μg L(-1) and a 2-fold enrichment factor (from 60 μL sample solution to 30 μL eluent) were achieved. The proposed method was further validated by analyzing CEA in human serum. The results were in good agreement with those obtained by chemiluminescent immunoassay, which is currently used as a clinical method. Overall, this method offers the advantages of high speed, high sensitivity, high selectivity, low sample/reagents consumption, high integrity and versatility. Moreover, it can be easily applied to other biological and medical assays.

High sensitive analysis of steroids in doping control using gas chromatography/time‐of‐flight mass‐spectrometry

The method of high sensitive gas chromatographic/time-of-flight mass-spectrometric (GC/TOF-MS) analysis of steroids was developed. Low-resolution TOF-MS instrument (with fast spectral acquisition rate) was used. This method is based on the formation of the silyl derivatives of steroids; exchange of the reagent mixture (pyridine and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA)) for tert-butylmethylether; offline large sample volume injection of this solution based on sorption concentration of the respective derivatives from the vapour-gas mixture flow formed from the solution and inert gas flows; and entire analytes solvent-free concentrate transfer into the injector of the gas chromatograph. Detection limits for 100 µl sample solution volume were 0.5-2 pg/µl (depending on the component). Application of TOF-MS model 'TruTOF' (Leco, St Joseph, MO, USA) coupled with gas chromatograph and ChromaTOF software (Leco, St Joseph, MO, USA) allowed extraction of the full mass spectra and resolving coeluted peaks. Due to use of the proposed method (10 µl sample aliquot) and GC/TOF-MS, two times more steroid-like compounds were registered in the urine extract in comparison with the injection of 1 µl of the same sample solution.

Carbon Nanotubes-Loaded Silica Gel for Preconcentration of Trace Silver with Detection by Flame Atomic Absorption Spectrometry

Abstract Carbon nanotubes (CNTs) were loaded onto the surface of silica gel (SG) beads, and the CNTs/SG composite was used as a novel adsorbent for the preconcentration of trace silver in a flow system by adsorbing nascent Ag2O in solution. This treatment of the material significantly improved the mechanical strength and capability of preconcentration of CNTs. With NaOH as precipitating reagent, the nascent Ag2O in the solution was readily retained on the surface of the CNTs/SG composite and recovered afterward by elution with nitric acid (10%, V/V). The eluate was finally introduced into a flame atomic absorption spectrometer for quantification. By loading 5.4 mL of sample solution, a liner range of 1–120 μg L−1, an enrichment factor of 34.5, a detection limit of 0.35 μg L−1 and a precision of 0.5% RSD at 40 μg L−1 level (n = 7) were obtained, along with a sampling frequency of 47 h−1. The enrichment factor, the detection limit and the precision of this procedure are obviously superior to those achieved by using wither pure CNTs or pure silica gel as adsorbents. The procedure was applied for the determination of silver in water samples, and satisfactory spiking recoveries were obtained in the range of 96%–108%.

Radiostrontium separation and measurement in a single step using plastic scintillators plus selective extractants. Application to aqueous sample analysis

This study describes a new protocol for 90Sr determination in water samples based on the use of a selective extractant (DtBuCH18C6) and plastic scintillator microspheres. The proposed procedure unifies chemical separation and sample measurement preparation in a single step to reduce the effort, time and reagents required for analysis. In addition, the final measurement does not produce mixed waste. The minimum activity detectable for 10 mL of sample solution is 0.46 Bq L −1. Relative errors for the determination of 90Sr activity in drinking, sea and river waters are less than 4%.

Evaluation of dispersive liquid–liquid microextraction for the simultaneous determination of chlorophenols and haloanisoles in wines and cork stoppers using gas chromatography–mass spectrometry

Dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography–mass spectrometry (GC–MS) was evaluated for the simultaneous determination of five chlorophenols and seven haloanisoles in wines and cork stoppers. Parameters, such as the nature and volume of the extracting and disperser solvents, extraction time, salt addition, centrifugation time and sample volume or mass, affecting the DLLME were carefully optimized to extract and preconcentrate chlorophenols, in the form of their acetylated derivatives, and haloanisoles. In this extraction method, 1 mL of acetone (disperser solvent) containing 30 μL of carbon tetrachloride (extraction solvent) was rapidly injected by a syringe into 5 mL of sample solution containing 200 μL of acetic anhydride (derivatizing reagent) and 0.5 mL of phosphate buffer solution, thereby forming a cloudy solution. After extraction, phase separation was performed by centrifugation, and a volume of 4 μL of the sedimented phase was analyzed by GC–MS. The wine samples were directly used for the DLLME extraction (red wines required a 1:1 dilution with water). For cork samples, the target analytes were first extracted with pentane, the solvent was evaporated and the residue reconstituted with acetone before DLLME. The use of an internal standard (2,4-dibromoanisole) notably improved the repeatability of the procedure. Under the optimized conditions, detection limits ranged from 0.004 to 0.108 ng mL −1 in wine samples (24–220 pg g −1 in corks), depending on the compound and the sample analyzed. The enrichment factors for haloanisoles were in the 380–700-fold range.

Determination of Aniline Derivatives in Water Samples by High Performance Liquid Chromatography Coupled with On-Line Flow Injection Preconcentration

An on-line SPE-HPLC method using a cigarette filter as the sorbent was developed and applied to analyze the aniline derivatives in water samples. A preconcentration column packed with cigarette filters was used to replace a conventional sample loop on the injector valve of an HPLC for on-line SPE. With the consumption of a 7.5 mL sample solution, the enhancement factors ranged from 287 to 349 in comparison with direct injections of 20 μL sample solution. The detection limits (S/N = 3) for preconcentration of 7.5 mL of sample solution ranged from 0.27 to 5.46 μg/L at a sample throughput of 6 samples per hour.

Ionic liquid templated porous nano-TiO2 particles for the selective isolation of cytochrome c

Porous nano-titanium dioxide (TiO2) particleswith anatase framework were prepared by using an effective template of hydrophobic ionic liquid, i.e.,N, N-bis [2-methylbutyl] imidazolium hexafluorophosphate ([PPim][PF6]). Thenano-TiO2 particles were characterized with TEM and BET, resulting in thedistribution of the pore diameters centering at 7.3 nm and 26.2 nm, attributedto the template effect of the ionic liquid and the aggregation of theTiO2 particles, respectively. A much improved surface area of 68.31 m2 g − 1 and a pore volume of0.2814 cm3 g − 1 were obtainedwith respect to 15.16 m2 g − 1 and 0.0402 cm3 g − 1 achieved bythe non-templated nano-TiO2 counterpart. The porous nano-TiO2 particles were used as adsorbent for selective adsorption and isolation of cytochrome c(cyt-c) at certain conditions. An adsorption efficiency of 87% was achieved for 150 µg ml − 1 cyt-c in 1.0 ml of sample solution at pH 9.0 by using 2.0 mg of the nano-TiO2 particles, in comparison to 30% obtained by the non-templated nano-TiO2. In addition, an adsorption capacity of 112.6 µg mg − 1 was derived forthe porous nano-TiO2 with respect to 25.1 µg mg − 1 for the normal ones. The absorbed cyt-c could be readily recovered by stripping with a 0.1 mol l − 1 Na3PO4 solution, giving rise to a recovery of ca. 90%. The porous nano-TiO2 particles have been used for the isolation of cyt-c from human whole blood, achievingsatisfactory results by assay with SDS-PAGE.

A novel method of synthesizing solid phase adsorbent silica modified with xylenol orange: application for separation, pre-concentration and determination of uranium in calcium rich hydro-geochemical samples and sea water—Part 1

A novel, single-step route has been developed for the synthesis of solid phase adsorbent silica modified with xylenol orange. The addition of cationic surfactant cetyl tri-methylammonium bromide during the synthesis of the adsorbent supports the formation of a stable coating of xylenol orange on silica. The adsorbent showed no signs of degradation in contact with organic solvents and with solutions of varying pH between 1 and 9. This adsorbent has been used for separation and pre-concentration of uranium from hydro-geochemical samples with high calcium content and from sea water. Quantitative sorption of uranium was observed above pH 3 and complete desorption can be achieved using 0.2 M sodium pyrophosphate solution. The uranium content in the extract was determined by laser fluorimetric technique. The equilibration time is 30 min. The sorption capacity of the adsorbent for uranium is 10 mg g−1. An enrichment factor of 50 was obtained by this procedure taking 500 mL of sample solution. Uranium concentrations down to 0.05 ng mL−1 can be determined after pre-concentration using this method. The relative standard deviation at an 0.1 ng mL−1 level is ±15%.

Separation and Preconcentration of Cobalt Using a New Schiff Base Derivative on Amberlite XAD‐7

AbstractIn this study, a new solid‐phase extraction procedure has been developed for preconcentration and determination of Co ions in different water samples by flame atomic absorption spectrometry (FAAS). Cobalt was preconcentrated as N,N′‐bis(pyridine‐2‐yl‐methyl)benzene‐1,4‐diamine (Co‐BPMBDA) from sample solutions using a column containing Amberlite XAD‐7 and was determined. In order to achieve the best performance for the method, effects of several parameters such as pH, concentrations of ligand, sample flow rate, eluent, and matrix ions on the method efficiency were investigated. Under optimum conditions, the preconcentration factor was found to be 200 for 1000 mL waters samples. Detection limit based on the 3Sb criterion was calculated as 0.24 µg/L for 100 mL of sample solution and relative standard deviation was found to be 1.8%. The method was applied to determine the trace amounts of cobalt in water samples.