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In the present work the determination of benzene, toluene, ethylbenzene and o-xylene (BTEX) in environmental sample solutions using gas chromatography with flame ionisation detection (GC-FID) combined with three different sampling techniques, such as; direct single drop microextraction (DI-SDME), headspace single drop microextraction (HS-SDME) and ultrasonic assisted HS-SDME, were compared. In all of these techniques, for the determination of BTEX, the experimental parameters such as organic solvent effect, extraction time, agitation speed and salting effect were optimised. At their optimised conditions of operation the detection limits, times of extraction and precision for the three techniques are established. A detailed comparison of the analytical performance characteristics of these techniques for final GC-FID determination of BTEX in water samples was given. The technique provided a linear range of 50–20000 ng mL–1 for DI-SDME and 10–20000 ng mL–1 for HS-SDME methods, good repeatability (RSDs

A novel microextraction method termed ionic liquid-based submerged single drop microextraction combining liquid chromatography (LC) was developed for the determination of aromatic amines in environmental water samples. This method is simple and rapid for the determination of three aromatic amines (2-nitroaniline, 3-chloroaniline and 4-bromoaniline) which were selected as model compounds for validation of this new mode of microextraction. This technique combines extraction and preconcentration of the analytes in one step before determination by LC-UV, and the ionic liquid was used instead of the organic solvent as extractant. Several important parameters influencing the extraction efficiency such as the volume of the aqueous sample solution (donor phase), extraction time, pH of the donor phase and salt effect were investigated. Under the optimized conditions, acceptable enrichment factors (132–186) and relative recoveries (82–98%) were obtained for the extraction of the target analytes in real water samples. The calibration curves were linear with correlation coefficients ranging from 0.9983 to 0.9989 and RSDs (n = 5) of 4.9–6.8%. The LODs for the three aromatic amines were 1–2.5 μg L−1 at a signal-to-noise ratio (S/N) of 3.

In this research, the sol–gel technology was applied for the preparation of solid-phase microextraction fibers for extracting of methyl tert-butyl ether (MTBE) from environmental water samples. For this purpose, two different polymers such as poly(ethylene glycol) (PEG) and combination of PEG and multiwall carbon nanotubes (MWCNTs) were prepared using sol–gel technology as coating procedure for the fibers. The pre-concentration process followed by GC–FID determination was used and the results evidenced that pre-concentration factor for PEG/CNTs fiber was approximately five times higher than PEG. Parameters affecting the extraction efficiency such as temperature, extraction time, stirring speed and salt effect for each fiber were investigated and optimized. On the optimal conditions, the linear range for MTBE with PEG and PEG/CNT fibers were 10–3,000 and 1–1,000 ng mL−1 and the detection limits (S/N = 3) were 1.0 and 0.3 ng mL−1, respectively. The sol–gel PEG/CNTs fiber has good performance and therefore relatively better figures of merit and experimental results such as thermal stability (up to 320 °C), average of life time (over 150 times) and repeatability (RSD

The purpose of the present work is to develop a simple, rapid, sensitive and accurate method for the derivatization and subsequently preconcentration of Hg(II) and the determination of its derivative, diphenylmercury, in natural water samples using gas chromatography-flame ionization detection. The method is based on the diphenylation using phenyl boronic acid, subsequent extraction of phenylmercury into a single drop of an organic solvent (toluene), followed by gas chromatography-flame ionization detection GC-FID analysis of the extract. The pH of the feed solution was kept in pH 5 with acetate buffer solution. Thus, the optimized conditions are: organic solvent, toluene; derivatization time, 10 min; extraction time, 15 min; microdrop volume, 1.6 μL; stirring rate, 600 rpm; sample volume, 5 mL. The limit of detection (LOD), calculated on the basis of five replicates was 0.02 μg mL−1. The relative standard deviation of the method (RSD%, n = 5) was 3.0. Linear range was between 0.05 and 5 μg mL−1 and preconcentration factor obtained for phenyl-mercury was 105.

The development of faster, simpler, inexpensive and more environmentally-friendly sample-preparation techniques is an important issue in chemical analysis. Recent research trends involve miniaturization of the traditional liquid-liquid-extraction principle by greatly reducing the acceptor-to-donor ratio. The current trend is towards simplification and miniaturization of sample preparation and decreasing the quantities of organic solvents used. We discuss liquid-phase microextraction with the focus on extraction principles, historical development and performance.

A new and fast hollow fiber based liquid phase microextraction (HF-LPME) method using volatile organic solvents coupled with high-performance liquid chromatography (HPLC) was developed for determination of aromatic amines in the environmental water samples. Analytes including 3-nitroaniline, 3-chloroaniline and 4-bromoaniline were extracted from 6 mL basic aqueous sample solution (donor phase, NaOH 1 mol L(-1)) into the thin film of organic solvent that surrounded and impregnated the pores of the polypropylene hollow fiber wall (toluene, 20 microL), then back-extracted into the 6 mL acidified aqueous solution (acceptor phase, HCl 0.5 mol L(-1)) in the lumen of the two-end sealed hollow fiber. After the extraction, 5 microL of the acceptor phase was withdrawn into the syringe and injected directly into the HPLC system for the analysis. The parameters influencing the extraction efficiency including the kind of organic solvent and its volume, composition of donor and acceptor phases and the volume ratio between them, extraction time, stirring rate, salt addition and the effect of the analyte complexation with 18-crown-6 ether were investigated and optimized. Under the optimal conditions (donor phase: 6 mL of 1 mol L(-1) NaOH with 10% NaCl; organic phase: 20 microL of toluene; acceptor phase: 6 microL of 0.5 mol L(-1) HCl and 600 mmol L(-1) 18-crown-6 ether; pre-extraction and back-extraction times: 75 s and 10 min, respectively; stirring rate: 800 rpm), the obtained EFs were between 259 and 674, dynamic linear ranges were 0.1-1000 microg L(-1) (R>0.9991), and also the limits of detection were in the range of 0.01-0.1 micro gL(-1). The proposed procedure worked very well for real environmental water samples with microgram per liter level of the analytes, and good relative recoveries (91-102%) were obtained for the spiked sample solutions.

The directly suspended droplet microextraction (DSDME) technique coupled with the capillary gas chromatography-flame ionization detector (GC-FID) was used to determine BTEX compounds in aqueous samples. The effective parameters such as organic solvent, extraction time, microdroplet volume, salt effect and stirring speed were optimized. The performance of the proposed technique was evaluated for the determination of BTEX compounds in natural water samples. Under the optimal conditions the enrichment factors ranged from 142.68 to 312.13, linear range; 0.01–20 μg mL −1 , limits of detection; 0.8–7 ng mL −1 for most analytes. Relative standard deviations for 0.2 μg mL −1 of BTEX in water were in the range 1.81–2.47% ( n = 5). The relative recoveries of BTEX from surface water at spiking level of 0.2 μg mL −1 were in the range of 89.87–98.62%.

Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-flame ionization detection (GC-FID) was applied for the determination of two tricyclic antidepressant drugs (TCAs), amitriptyline and nortriptyline, from water samples. This method is a very simple and rapid method for the extraction and preconcentration of these drugs from environmental sample solutions. In this method, the appropriate mixture of extraction solvent (18 microL Carbon tetrachloride) and disperser solvent (1 mL methanol) are injected rapidly into the aqueous sample (5.0 mL) by syringe. Therefore, cloudy solution is formed. In fact, it is consisted of fine particles of extraction solvent which is dispersed entirely into aqueous phase. The mixture was centrifuged and the extraction solvent is sedimented on the bottom of the conical test tube. 2.0 microL of the sedimented phase is injected into the GC for separation and determination of TCAs. Some important parameters, such as kind of extraction and disperser solvent and volume of them, extraction time, pH and ionic strength of the aqueous feed solution were optimized. Under the optimal conditions, the enrichment factors and extraction recoveries were between 740.04-1000.25 and 54.76-74.02%, respectively. The linear range was (0.005-16 microg mL(-1)) and limits of detection were between 0.005 and 0.01 microg mL(-1) for each of the analytes. The relative standard deviations (R.S.D.) for 4 microg mL(-1) of TCAs in water were in the range of 5.6-6.4 (n=6). The performance of the proposed technique was evaluated for determination of TCAs in blood plasma.

Directly suspended droplet liquid–liquid–liquid microextraction (LLLME) has been used to determine residues of diclofenac (2-[2-(2,6-dichlorophenyl) aminophenyl] ethanoic acid), in environmental water samples. In this technique a free suspended droplet of an aqueous solvent is delivered to the top-center position of an immiscible organic solvent floating on the top of an aqueous sample while being agitated by a stirring bar placed on the bottom of the sample cell. Recently, diclofenac was found as an environmental contaminant in sewage, surface, ground and drinking water samples. In the present work, diclofenac was extracted from water samples by LLLME and analysed by HPLC with UV detection at 281 nm. Factors such as organic solvent, extraction and back extraction times, stirring rate and the pH of acceptor and donor phases were optimized. Enrichment factor and detection limit (LOD, n = 7) were 102 and 0.1 μg L−1, respectively. The linearity ranged from 0.5 to 2,000 μg−1 with a %RSD (n = 5) of 7.2 at S/N = 3. All experiments were carried out at room temperature (22 ± 0.5 °C).

Directly Suspended Droplet Microextraction (DSDME) was used for the determination of two tricyclic antidepressant drugs (TCAs), amitriptyline and nortriptyline. In this technique, an aqueous sample is agitated with a stirring bar, creating a mild vortex at the center of the vial. A droplet of an immiscible organic solvent is placed at the bottom of the vortex. After 20 min a portion of the organic droplet is withdrawn with a syringe and injected into the GC. Experimental conditions, such as the extraction solvent, extraction time, solvent volume, stirring rate, pH and salt addition were optimized. In order to evaluate the practical application of the method, relative standard deviations, linearity range and limits of detection were calculated. Typical enrichment factors were 167 and 179 for amitriptyline and nortriptyline, respectively. The method was applied to the determination of these drugs in urine samples.

In this research, poly (ethylene glycol)-poly (ethylene glycol) grafted flower-like cupric oxidenano particles (PEG-PEG-g-CuO NPs) as a novel fiber coating of solid-phase microextraction (SPME) were synthesized by using sol–gel technology. This fiber was successfully applied to extract and determine the ultra-trace levels of benzene, toluene, ethyl benzene and o-xylene in human hair using head space-solid-phase microextraction (HS-SPME) coupled to gas chromatography-flame ionization detector. Characterization and chemical composition of the nano particle was performed by Fourier transform infrared spectroscopy (FT-IR), energy dispersion spectroscopy (EDS) and back scatter analysis (BSA). These methods confirmed the successful fabrication of PEG-g-CuO NPs. The surface morphology of the fibers were inspected by scanning electron microscopy. The scanning electron microscopy (SEM) revealed many “crack-like” features and highly porous structure on the surface of fiber. The synthesized nanocomposites were used for preconcentration and extraction of benzene, toluene, ethyl benzene and o-xylene (BTEX). The effects of operating parameters such as: desorption temperature and time, extraction temperature, extraction time, stirring speed and salt effect were investigated and optimized. Under the optimal conditions, the method detection limits and the limits of quantification were between 0.00025–50.00000 pg mL−1 and 0.00200–200.00000 pg mL−1, respectively. Linearity was observed over a range 0.00200–200000.00000 pg mL−1. The relative standard deviations for one fiber (repeatability; n = 5) were obtained from 3.30 up to 5.01% and between fibers or batch to batch (n = 3; reproducibility) in the range of 3.63–6.21%. The developed method was successfully applied to simultaneous determination of BTEX in human hairs, tap water and distillate water.

The development of rapid, inexpensive, and environmentally friendly sample-preparation techniques is a serious issue in chemical analysis. This explains the success of two new miniaturized liquid-phase microextraction techniques used as sample-preconcentration techniques for liquid chromatography – hollow fiber and single-drop liquid-phase microextraction. In hollow-fiber-based microextraction (HFME) a hollow fiber is filled with an organic solvent to establish and protect micro volumes of acceptor solution. This attractive, simple, low cost method, which is highly selective and enables substantial enrichment, has been compared with single-drop microextraction (SDME), using four aniline derivatives (3-chloroaniline, 3-bromoaniline, 2-nitroaniline, and 4-nitroaniline) as model compounds. The most important conditions and practical considerations for method optimization are discussed. The results showed that enrichment factors varied from 91.0 to 180.1 for SDME and from 106.43 to 286.33 for HFME. Extraction times were approximately equal. Stirring speeds selected for SDME and HFME were 800 and 900 rev min−1, respectively. Other quantitative data were almost identical.

A novel method for the extraction of aromatic amines present in water samples is produced here coupling two-step liquid-phase microextraction with high performance liquid chromatography by using a monolithic column. The hydrophobic porous polypropylene membranes were used as the interface between the donor water sample and the acceptor aqueous solution. In the first step, the analytes were extracted from a sample solution (pH 13) as donor phase into the organic phase, benzyl alcohol-ethyl acetate (80-20%, v/v) immobilized in the pores of a polypropylene dish and further into an acidified acceptor phase (pH 2) inside the polypropylene membrane. This step had about 100% relative recovery with an enrichment factors of over 59.9. For the second step, using a single piece of polypropylene hollow fiber, was shaped with a star liked profile as the acceptor phase. The acceptor solution in the first step was the donor phase for the second step. This solution was adjusted again to pH 13 with NaOH solution. Five microlitres of HCl solution (pH 2) as the acceptor phase was added to the hollow fiber, star liked profile, as the acceptor phase. This acceptor solution, after the second extraction step, was subsequently withdrawn into a micro syringe and directly injected into an HPLC system for analysis. With this two-step microextraction, total enrichment factors of >6000 could be obtained and detection limits of < or = 250.0 ng/l (S/N = 3)could be achieved. The calibration curves for analytes were linear within the range of 20.0 ng/l to 300 microg/l. All expreriments were carried out at room temperature, 22 +/- 0.5 degrees C.

A simple liquid–liquid–liquid microextraction device of new design was used to pre-concentrate phenols from water samples before liquid chromatographic (LC) analysis. Extraction was induced by the pH difference inside and outside an organic phase located at the interface. The pH of the donor phase outside the organic phase was adjusted to 1 with HCl whereas the acceptor phase was a basic solution at pH 13. On stirring neutral phenols were extracted into the organic solvent then back-extracted into 1 μL of basic acceptor solution suspended from the tip of a micro syringe. The acceptor phase was then withdrawn into the micro syringe and injected directly into the LC. The technique uses a low-cost disposable extraction ‘device’ and is very convenient to operate. Up to 230-fold enrichment of analytes could be achieved. This procedure could also serve as a sample clean-up step because neutral and basic compounds were not extracted into the acceptor phase. The RSD (n = 5) was better than 6.2% and the linear calibration range was from 1 to 1000 µg–L−1 with r 2 ≥ 0.992. Optimization of experimental conditions (rate of stirring, ionic strength of the sample solution, concentration of reagents, time of extraction, and organic solvent volume) were also examined. The method was applied to the determination of phenols in tap and well waters.

The classic silver diethyldithiocarbamate (SDDC) spectrophotometric procedure for arsenic determination has been used for investigation of the effect of cathodic electrolyte on the performance of electrochemical hydride generation (HG) from graphite cathode. The results of this study show that the presence of a soft metal ion such as Cd(II), Sn(II) and/or Zn(II) in the acidic cathodic electrolyte can increase effectively the efficiency of electrochemical hydride generation and decrease the effect of interferences. The possible mechanisms of these effects have been discussed in detail. The parameters related to the electrochemical hydride generation were investigated. Also the characteristic data of the electrochemical hydride generation and common hydride generation by NaBH4 were compared. Under optimised conditions, the system is selective to As(III) and total inorganic analyses can be performed after a pre-reduction stage prior to electrochemical hydride generation. This will allow the differential determination of inorganic arsenic species. The method is appropriate to the determination of 4–40 μg of each arsenic species.

A novel sample preparation technique, membrane extraction with a sorbent interface (MESI) has been optimized and used for continuous monitoring thermal degradation products in polyacrylonitrile (PAN) polymer headspace at different temperatures, followed by gas chromatography-mass spectrometry (GC-MS). MESI with a flat sheet poly(dimethyl siloxane)-polycarbonate (PDMS-PC) membrane and Tenax trap was used. The system is very simple, fast and reliable and allowed us to extract, enrich and continuously monitor major volatile compounds released from the polymer at different temperatures. The volatile and semi-volatile gaseous degradation products were identified. Sensitivity of the method depends on the length of time for trapping.

The complexes of Tl+, Pb2+ and Cd2+ cations with the macrocyclic ligand, dicyclohexano-18-crown-6\linebreak(DC18C6) were studied in water/methanol (H2+O/MeOH), water/1-propanol (H2+O/1-PrOH), water/acetonitrile (H2+O/AN), water/dimethylformamide (H2+O/DMF), dimethylformamide/acetonitrile (DMF/AN), dimethylformamide/methanol (DMF/MeOH), dimethylformamide/1-propanol (DMF/1-PrOH) and dimethylformamide/nitromethane (DMF/NM) mixed solvents at 22 °C using differential pulse polarography (DPP), square wave polarography and conductometry. In general, the stability of the complexes was found to decrease with increasing concentration of water in aqueous/non-aqueous mixed solvents with an inverse relationship between the stability constants of the complexes and the concentration of DMF in non-aqueous mixed solvents. The results show that the change in stability of DC18C6.Tl+, vs the composition of solvent in DMF/AN and DMF/NM mixed solvents is apparently different from that in DMF/MeOH and DMF/1-PrOH mixed solvents. While the variation of stability constants of the DC18C6.Tl+ and DC18C6.Pb2+ complexes vs the composition of H2+O/AN mixed solvents is monotonic, an anomalous behavior was observed for variations of log Kf vs the composition of H2+O/1-PrOH and H2+O/MeOH mixed solvents. The selectivity order of the DC18C6 ligand for the cations was found to be Pb2+ > Tl+ > Cd2+.

The complexation of Tl+, Pb2+and Cd2+ cations by macrocyclic ligands, aza-18-crown-6 (L1) and dibenzopyridino-18-crown-6 (L2) was studied in some binary mixtures of methanol (MeOH), n-propanol (n-PrOH), nitromethane (NM) and acetonitrile (AN) with dimethylformamide (DMF) at 22 °C using DC (direct current) and differential pulse polarographic techniques (DPP). The stoichiometry and stability constants of the complexes were determined by monitoring the shifts in half-waves or peak potentials of the polarographic waves of metal ions against the ligand concentration. In all of the solvent systems, the stability of the resulting 1:1 complexes was found to be L1 > L2. The selectivity order of the L2 ligand for the cations was found to be Pb2+ > Tl+ > Cd2+ and the selectivity of the L1 ligand for Pb2+ ion was greater than that of Tl+ ion. The results show that the stability of the complexes depends on the nature and composition of the mixed solvents. There is an inverse relationship between the stability constants of the complexes and the amount of dimethylformamide in the mixed solvent systems.

The volatile platinum(II) complex of N,N-ethylenebis(5,5-dimethyl-4-oxohexane-2-imine) (H2APM2en) eluted quantitatively from a GC capillary column and has been used to establish operating parameters and to gain figures of merit for atomic emission detection of platinum with microwave-induced plasma atomic emission. Two recipes have been developed for platinum; at 266 nm for simultaneous monitoring the carbon emission at 248 nm, and at 300 nm for simultaneous determinations with copper and nickel at 325 nm and 301 nm, respectively. Optimum platinum emission was observed using oxygen and hydrogen as reagent gases and high flow-rate of helium as make-up gas. Linear calibration ranges at 266 nm and 300 nm were assessed and, platinum emission being approximately five-times more sensitive at 300 nm than at 266 nm. The detection limit at 300 nm was observed as 65 pg/s. Selectivity of platinum emission over carbon at both wavelengths 266 nm and 300 nm is in the range of 105–106.

In this research, the headspace solid-phase microextraction (SPME) coupled with GC flame ionization detector was applied for the determination of some monocyclic aromatic amines in real water and urine samples. A sol-gel technique was applied for the preparation of the SPME fibers. Two different sol-gel coatings, (PEG and poly(ethylene glycol) modified with multi-walled carbon nanotubes [PEG/CNTs]), were prepared and compared. Extraction efficiency of PEG/CNTs was better than PEG fiber in the same conditions. To obtain maximum extraction efficiency, some parameters such as desorption temperature and time, temperature and time of extraction, salt effect, pH, and stirring speed were investigated and optimized for PEG/CNTs fiber. Under optimized conditions, the LODs (S/N = 3) were in the range of 0.5-50 ng/L and limits of quantification (S/N = 10) were between 1 and 500 ng/L. Repeatability (n = 5) was in the range of 3.2-9.1% and reproducibility (n = 3) was obtained from 5.5 to 12.0%. The method was successfully applied to the analysis of real water and urine samples with recoveries from 63.7 to 97.0%.

In this study, poly(ethylene glycol) (PEG) grafted onto multi-walled carbon nanotubes (PEG-g-MWCNTs) were synthesized by the covalent functionalization of MWCNTs with hydroxyl-terminated PEG chains. For the first time, functionalized product of PEG-g-MWCNTs was used as selective stationary phase to prepare the sol-gel solid-phase microextraction (SPME) fiber in combination with gas chromatography-flame ionization detector (GC-FID) for the determination of ultra-trace levels of benzene, toluene, ethylbenzene and o-xylene (BTEX) in real water samples. The PEG-g-MWCNTs were characterized by Fourier transform infrared spectra and also thermo-gravimetric analysis, which verified that PEG chains were grafted onto the surface of the MWCNTs. The scanning electron micrographs of the fiber surface revealed a highly porous structure which greatly increases the surface area for PEG-g-MWCNTs sol-gel coating. This fiber demonstrated many inherent advantages, the main being the strong anchoring of the coating to the fused silica resulting from chemical bonding with the silanol groups on the fused-silica fiber surface. The new PEG-g-MWCNTs sol-gel fiber is simple to prepare, robust, with high thermal stability and long lifetime, up to 200 extractions. Important parameters influencing the extraction efficiency such as desorption temperature and time, extraction temperature, extraction time, stirring speed and salt effect were investigated and optimized. Under the optimal conditions, the method detection limits (S/N=3) were in the range of 0.6-3 pg mL(-1) and the limits of quantification (S/N=10) between 2 and 10 pg mL(-1). The relative standard deviations (RSDs) for one fiber (repeatability) (n=5) were obtained from 4.40 up to 5.75% and between fibers or batch to batch (n=3) (reproducibility) in the range of 4.31-6.55%. The developed method was successfully applied to real water samples while the relative recovery percentages obtained for the spiked water samples at 20 pg mL(-1) were from 90.21 to 101.90%.

Four tetradentate β-ketoamine reagents were examined for derivatization and the separation of copper and nickel as their chelates, by capillary GC using flame ionization detection. Complete separation between copper and nickel complexes was obtained in each case. The chelates were also evaluated for simultaneous, selective and sensitive spectral detection of copper and nickel at 325 and 301 nm, respectively, using microwave-induced plasma atomic emission detection. The selectivity of copper at 325 nm with respect to nickel was high; some response of copper at the nickel emission line was observed, but it did not interfere with the determination of nickel. The reagent H 2 (pnAA 2 ) was used for the analysis of copper and nickel in an ore sample. The detection limits for both copper and nickel were 0.8 pg reaching the detector.

Capillary column gas chromatography (GC) with flame ionization detection (FID) or microwave induced plasma atomic emission detection (MIP-AED) were examined for the determination of chloride, using phenylboronic acid as derivatizing reagent. Phenylboronic acid and mercuric nitrate were used in a 1:1 molar ratio to produce phenylmercuric chloride (PMC). The limit of detection for chloride as PMC using FID was 3.3·10 −10 g and using AED, measuring the mercury response at 185 nm, it was 6.25·10 −11 g. Under the conditions used, chloride and bromide (as PMC and PMB) failed to separate adequately, but they could be determined by GC-AED using the wavelenghts 478 nm and 479 nm for bromide and chloride, respectively. The specific detection limits for bromide and chloride obtained from bromine and chlorine responses were 2.9·10 −9 g and 1.8·10 −9 g per injection.

In the present work, a sample pre-treatment technique for the determination of trace concentrations of benzene, toluene, ethyl benzene and xylene (BTEX) in aqueous samples has been developed and applied to analysis of the selected analytes in environmental water samples. The extraction procedure is based on coupling polypropylene hollow-fiber liquid phase microextraction (HF-LPME) with gas chromatography by flame ionization detection (GC-FID). The effective parameters such as organic solvent, extraction time, agitation speed and salting effect were investigated. Good reproducibilities of the extraction performance were obtained, with the RSD values ranging from 2.02 to 4.61% (n=5). The method provided 41.47-128.01 fold preconcentration of the target analytes. The limits of detections for the BTEX were in the range of 0.005-03microg ml(-1). In addition, sample clean-up was achieved during LPME due to the selectivity of the hollow fiber, which prevented undesirable large molecules from being extracted. Real samples (River and waste waters) containing BTEX were examined using this method with good linearity and precision (RSDs most lower than 6.00%, n=5). All experiments were carried out at room temperature, 22+/-0.5 degrees C.

The aim of this study was to evaluate the performance of a technique for simultaneous testing of hydrophilic abuse drugs in hair. The analysis of, codeine and methadone in morphine hair included incubation in methanol (5h, 50 degrees C), Surfactant enhanced liquid-phase microextraction (SE-LPME) and HPLC analysis. This study has demonstrated that SE-LPME constitute a real alternative to the other liquid-phase microextraction methods, for pre-concentration and extraction of hydrophilic drugs in biological samples and has shown the advantages of these optimized methodologies over the traditional microextraction techniques. For these drugs recoveries in the range of 57.5-93.7 were obtained from hair. The drugs were enriched by a factor of 61-128 during SE-LPME. Linearity (r2, 0.9982-0.9997) was obtained in the range of 50-500 microg/l for morphine and 10-500 microg/l for codeine and methadone.

Liquid-liquid-liquid phase microextraction (LLLME) coupled with high-performance liquid chromatography (HPLC) for the analysis of some aromatic amines is described. These compounds were extracted from 4.0mL aqueous sample that adjusted to pH 13 with, NaOH-NaCl buffer solution (donor phase, P(1)) into an organic phase (P(2)) 150mul benzyl alcohol and ethyl acetate (2:1) and then back extracted into a microdrop of aqueous acceptor phase (P(3)), adjusted at pH 2, with Na(2)HPO(4)-H(3)PO(4) buffer solution. The extraction time, T(1) (from P(1) to P(2)) was 20min and T(2) (from P(2) to P(3)) was 1min. Different crown ethers as complexing agents for amines were added to the acceptor phase to improve the extraction time. Factors such as organic solvents, extraction times, and addition of crown ethers to acceptor phase and stirring rate were optimised. The method was applied for determination of aromatic amines in wastewater samples. Enrichment factors ranged from 184.5 to 389.7. The linearity range was from 3 to 1000ng/ml and the detection limits varied from 0.8 to 1.80ng/ml. Relative standard deviations (%, n=5) were found (at S/N 3) in the range of 1.9 to 10.1. All experiments were carried out at room temperature, 22+/-0.5 degrees C.

Removal of 2-chlorophenol by ultrasonic waves (sonolysis), inorganic catalyst, and a combination of the two processes was tested and compared with each technique. In sonolysis, 2-chlorophenol mostly degraded indirectly in the bulk of solution by the radicals produced in the cavitation process. In catalyst treatment, the removal was performed in the presence of Al2O3, TiO2 and CuO. The highest removal was achieved in the presence of TiO2 for this pollutant. In the combined method an enhancement was observed for the removal of 2-chlorophenol. This could be attributed primarily to the continuous cleaning and chemical activation of the catalyst by acoustic cavitation. The mass transfer between the liquid phase and the catalyst and also the surface area of the catalyst are accelerated by the ultrasonic waves. The removal of 2-chlorophenol was performed under different intensities of irradiation, temperatures and quantities of catalyst. Some experiments were conducted in the presence of a Fenton reagent. In kinetic point of view, the removal of pollutant showed a pseudo-first order behavior. The combined method had a higher rate coefficient than sonolysis and catalyst treatment individually. Under some conditions, the presence of ultrasound has increased the rate coefficient of removal to about 10 times that in the absence of ultrasound.

Phenolic compounds have become a cause for worldwide concern due to their persistence, toxicity and health risks. This paper reports a three-step approach to remove 2-chlorophenol from dilute aqueous solution and compares each technique. The first step utilizes Horse Radish Peroxidase (HRP) in presence of hydrogen peroxide to oxidize this organic pollutant (enzyme treatment). For a more efficient removal of 2-chlorophenol, it is necessary to add the enzyme solution gradually to the contents of the reactor instead of rapid addition. The second step, involving ultrasonic waves eliminated 2-chlorophenol through hydroxyl radical generated by the cavitation process (sono-degradation). In the third step, a combination of ultrasonic waves and enzyme was used (sono-enzyme degradation). It should be mentioned that, the enzyme can be active in the presence of ultrasonic waves under the proper sonication. The degradation has been studied at different temperatures, intensities of irradiation, and concentrations of enzyme. The rate of degradation exhibited pseudo-first order behavior and the combination method was more effective than sonolysis and enzyme treatment individually.

In this study, sol–gel hybrid organic–inorganic materials were prepared in the presence of polyethyleneoxide (PEO) non-ionic surfactants (Triton X-100), which act as co-porogenic agents. For the first time, non-ionic surfactant mediated sol–gel coatings were evaluated by analyzing benzene, toluene, ethylbenzene and o-xylene (BTEX) in the aqueous samples. Two different fiber coatings were prepared including: un-modified poly(dimethylsiloxane) (PDMS) coating prepared from PDMS in the absence of Triton X-100 as a non-ionic surfactant (PDMS-no TX100), and modified PDMS coating prepared from this polymer in the presence of Triton X-100 as a porogenic agent and conditioned at a higher temperature than decomposition temperature of a non-ionic surfactant (PDMS-TX100). After the analytical procedure was optimized, the dynamic linear range obtained using PDMS-TX100 and PDMS-no TX100 fibers was 4–200 000 and 100–200 000 pg mL−1 and the limits of detection (S/N = 3) were 1–3 and 30–300 pg mL−1, respectively. The relative standard deviations (RSDs) for one fiber (repeatability) (n = 5) were from 3.1 up to 6.2% and between fibers or batch to batch (reproducibility) (n = 3) in the range of 4.2–7.7% for three fibers. The developed method was successfully applied to the real water samples while the relative recovery percentages obtained for the spiked water samples at 20 pg mL−1 of each analyte were from 94.41 to 104.05%.

A simple, sensitive, and accurate method for the determination of methyl tert-butyl ether (MTBE) in water samples has been developed based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-flame ionization detection (GC-FID). A sol–gel based coating fiber using poly(ethylene glycol) (PEG) grafted onto multi-walled carbon nanotubes (PEG-g-MWCNTs) as the extraction phase was prepared and used for the extraction of MTBE. The relative standard deviations (RSDs) for one fiber (repeatability) (n = 6) and between fibers or batch to batch (reproducibility) (n = 3) were obtained. The repeatability was assessed at low (0.1 ng mL−1) and high (100 ng mL−1) concentrations and the RSDs obtained were 5.3 and 4.1%, respectively. The reproducibility obtained for a concentration of 0.1 ng mL−1 was 6.5%. The calibration curve of MTBE was linear in the range from 0.07 to 500 ng mL−1. The limits of detection (S/N = 3) of 0.01 ng mL−1 and the limits of quantification (S/N = 10) of 0.07 ng mL−1 were obtained. The developed method was applied successfully to determine trace level of MTBE in real water samples. The relative recoveries for the spiked samples with 5 ng mL−1 of MTBE were ranged from 91 to 112% and the relative standard deviations were less than 7.8%.

In this research, a headspace solid-phase microextraction (HS-SPME) method, based on sol–gel poly(ethylene glycol) reinforced with multi-walled carbon nanotubes (PEG/CNTs) coated fiber, prior to gas chromatography-flame ionization detector (GC-FID), was proposed for the determination of phenolic compounds in water and urine samples. Under the optimized conditions, the linear range for phenol and cresols was 0.005–100 ng mL−1, the limit of detection (S/N = 3) was 0.001 to 0.1 ng mL−1 and the limit of quantification (LOQ) was 0.005 to 0.5 ng mL−1. The relative standard deviations (RSDs) for one fiber (repeatability) (n = 5) were obtained from 5.4 up to 7.1%, and between fibers, or batch to batch (n = 3), (reproducibility) in the range of 8.3–10.5%. The proposed HS-SPME-GC-FID method was successfully applied for the extraction of phenol and cresols from complex matrices such as wastewater and urine samples. Relative recoveries ranged from 85.3 to 99.5% for water samples and from 95.2 to 101.1% for urine samples.

Sol–gel technology was applied for the preparation of three solid-phase microextraction (SPME) fibers for the extraction of volatile organic compounds (VOCs) from environmental water samples using the gas chromatography-flame ionization detector (GC–FID). The compounds studied were methyl tert-butyl ether (MTBE), tetrahydrofuran (THF), benzene, n-heptane, methyl isobuthyl ketone (MIBK), toluene, tetrachloroethylene, ethylbenzene and o-xylene. These fibers were prepared from different coating polymers including poly(dimethylsiloxane) (PDMS), poly(ethylene glycol) (PEG) and PEG reinforced with multi-walled carbon nanotubes (MWCNTs). Important parameters influencing the extraction efficiency such as extraction temperature, extraction time, stirring speed, salt effect and desorption temperature were investigated and optimized for each fiber. Under the optimal conditions, the dynamic linear range with PDMS, PEG and PEG/CNTs fibers were 0.05–2000, 0.004–2000 and 0.002–2000 ng mL−1 and the detection limits (S/N = 3) were 0.02–10, 0.002–1 and 0.001–0.5 ng mL−1, respectively. The relative standard deviations (RSD) for one fiber (Repeatability) (n = 3) were obtained from 3.23 up to 7.57% and between fibers or batch to batch (n = 3) (Reproducibility) in the range of 2.91–8.91% for three fibers. However, PEG/CNTs fiber was the best one and the efficiency of PEG/CNTs was approximately 3 times and twice more than PDMS and PEG at the same conditions for most analytes respectively.

Thermally stable SPME sol–gel based fibers were made and applied as a sorbent onto the home made SPME holder for extraction of BTEX from water samples. Three different sol-gel coatings were made: non-polar, polar and polar reinforced with multi-walled carbon nanotubes and used as the bonded phase on the surface of the fibers. Extraction efficiency of carbon nanotubes reinforced fiber was approximately 7 times more than non-polar and 2 times more than polar fiber at the same conditions. Linear ranges, detection limits and analytes pre-concentration factors were determined. Repeatability and reproducibility of these fibers were also compared with each others.