Emulsification Microextraction Research Articles

Development of ultrasound-assisted emulsification microextraction based on solidification of a floating organic droplet for determination of organochlorine pesticides in water samples.

An ultrasound-assisted emulsification microextraction based on the solidification of a floating organic droplet followed by gas chromatography with electron capture detection was developed for the simultaneous determination of 13 organochlorine pesticides in water samples. In the proposed method, ultrasound was applied to achieve the emulsification without addition of any dispersive solvent. In consequence, the volume of extraction phase remained unaffected by the ion strength of aqueous phase and high extraction recoveries were obtained. It was also found that dilution of the floating phase with acetone was necessary for preventing peak splitting in chromatogram. Under optimal conditions, the proposed method provided good sensitivity (the detection limits of organochlorine pesticides ranged from 1.3 to 3.9 ng/L) and good repeatability of extraction (below 6.5%, n = 5). The recoveries in reservoir and river water samples were between 75.8% and 96.9%.

Determination of sixteen pyrethroids in water using dispersive liquid–liquid microextraction based on dissolved carbon dioxide flotation after emulsification microextraction using gas chromatography with triple quadrupole mass spectrometry

A simple and novel method was successfully developed for determination of sixteen pyrethroids in water samples by using DCF-DLLME coupled with GC-MS/MS.

Ionic liquid based microextraction of targeted lipids from serum using UPLC-MS/MS with a chemometric approach: a pilot study

An ionic liquid based vortex assisted surfactant-enhanced emulsification microextraction method followed by using liquid chromatography-electrospray mass spectrometry have been used for the determination of fatty acids, triglycerides and phospholipids in serum samples.

Tandem dispersive liquid–liquid microextraction as an efficient method for determination of basic drugs in complicated matrices

A simple and efficient approach is introduced for the improvement of the clean-up and applicability of the dispersive liquid–liquid microextraction (DLLME) method in complicated matrices. For this purpose, two dispersive microextraction methods were combined, and the tandem dispersive liquid–liquid microextraction (TDLLME) method was provided. At first, using the ultrasound-assisted emulsification microextraction (USAEME) method, the tricyclic anti-depressant (TCA) drugs nortriptyline, imipramine, and amitriptyline, as the model compounds, contained in an aqueous sample solution (8.0mL), were extracted into an organic solvent (35μL). Then by utilizing the air-agitated liquid–liquid microextraction (AALLME) method, these analytes were simply back-extracted into 50μL of an aqueous acceptor phase. By performing this convenient extraction method, a high sample clean-up was obtained; the overall extraction time was 7min. The back-extraction step could be performed in less than 2min, and very simple tools were required for this purpose. The response surface methodology (RSM) was used for the optimization of the experimental parameters so that the volumes 95 and 50μL were obtained for the organic solvent and the acceptor phase, respectively, and the pH values of 11.25 and 1.75 were obtained for the donor and acceptor phases, respectively, as the optimal extraction conditions. Under the optimized conditions, TDLLME-HPLC-UV provided a good linearity in the range of 2.5–5000ngmL−1, low limits of detection (0.7–1.0ngmL−1), good extraction repeatabilities (relative standard deviations below 6.2%, n=5), and enrichment factors (EFs) of 50–101. Finally, the developed method was successfully used for the determination of the mentioned drugs in the wastewater and human plasma samples.

Vortex-assisted surfactant-enhanced emulsification microextraction based on solidification of floating organic drop combined with high performance liquid chromatography for determination of naproxen and nabumetone

A novel, rapid, simple and green vortex-assisted surfactant-enhanced emulsification microextraction method based on solidification of floating organic drop was developed for simultaneous separation/preconcentration and determination of ultra trace amounts of naproxen and nabumetone with high performance liquid chromatography-fluorescence detection. Some parameters influencing the extraction efficiency of analytes such as type and volume of extractant, type and concentration of surfactant, sample pH, KCl concentration, sample volume, and vortex time were investigated and optimized. Under optimal conditions, the calibration graph exhibited linearity in the range of 3.0–300.0ngL−1 for naproxen and 7.0–300.0ngL−1 for nabumetone with a good coefficient of determination (R2>0.999). The limits of detection were 0.9 and 2.1ngL−1. The relative standard deviations for inter- and intra-day assays were in the range of 5.8–10.1% and 3.8–6.1%, respectively. The method was applied to the determination of naproxen and nabumetone in urine, water, wastewater and milk samples and the accuracy was evaluated through recovery experiments.

Measurement of selected polychlorinated biphenyls (PCBs) in water via ultrasound assisted emulsification-microextraction (USAEME) using low-density organic solvents.

Despite bans and restrictions for their adverse health effects including endocrine disruption, due to their stability in the environment, polychlorinated biphenyls (PCBs) are still of concern for their residues in several matrices. This study employed low-density ultrasound-assisted emulsification-microextraction (USAEME) to measure selected PCBs (28, 52, 101, 118, 138, 153, and 180) in water samples for gas chromatography-mass spectrometry analysis. Among tested solvents (isooctane, chloroform, hexane, and cyclohexane), 200 μL isooctane resulted in the highest yield for a 10 mL sample. The optimized method was validated and yielded recoveries of 87.29-92.83% with the limit of detection and limit of quantification (LOQ) values 3-12 ng/L and 10-40 ng/L, respectively. Twelve tap water samples collected in September 2014 were screened using this simple, rapid, and validated method. PCB concentrations in two samples were above the LOQ values; one sample contained 1,380 ng/L of PCB 118, 530 ng/L of PCB 138, and 152 ng/L of PCB 153, and the other contained 444 ng/L of PCB 138. Despite the city water supply being clean and the municipality employing all available measures to ensure clean water supply, the general public must be made aware of the regular maintenance of local water pipelines and storage tanks for the prevention of PCB contamination.

Lactic Acid Determination in Human Plasma Using Ultrasound-Assisted Emulsification Microextraction Followed by Gas Chromatography

A rapid, sensitive, and accurate analytical method was developed for determination of lactic acid (LA) in human plasma to monitor lactic acidosis. This method was based on an ultrasound-assisted emulsification microextraction (USAEME) method followed by gas chromatography with flame ionization detection (GC–FID). Derivatization of LA was carried out by a low density alcoholic solvent which performs both as an extraction solvent and derivatization agent, simultaneously. In this procedure, 100 μL of binary mixtures of pentan-1-ol with toluene (70 : 30, v/v %) was slowly injected into a 10 mL acidified aqueous sample of LA placed into an ultrasonic water bath. The resulting emulsion was centrifuged and after derivatization, 2 μL of organic phase was analysed by GC–FID. The effective variables were evaluated to optimize the efficiency of USAEME. Under the optimum conditions, good linearity in the range of 0.06–7.77 mmol L–1 was obtained with a correlation coefficient (R2) of 0.991 and a limit of detection (LOD) of 0.04 mmol L–1 for water samples. The inter-day and intra-day repeatability of the proposed method in human plasma were evaluated in terms of the relative standard deviation (RSD %) and were found to be <10 %. The results revealed that the USAEME–GC–FID method can be applied successfully for determination of LA in human plasma samples with satisfactory accuracy and precision.

Ultrasound-assisted emulsification microextraction followed by gas chromatography–mass spectrometry and gas chromatography–tandem mass spectrometry for the analysis of UV filters in water

A methodology based on ultrasound-assisted emulsification microextraction (USAEME) has been developed for the simultaneous analysis of ten UV filters (2-ethylhexyl methoxycinnamate (2EHMC), 4- methylbencylidene camphor (4MBC), benzyl salicylate (BS), ethylhexyl dimethyl PABA (EHPABA), ethylhexyl salicylate (EHS), etocrylene (Eto), homosalate (HMS), isoamyl methoxycinnamate (IAMC), menthyl anthranilate (MA) and octocrylene (OCR)) in different water samples employing two detection modes, gas chromatography–mass spectrometry (GC–MS), and gas chromatography–tandem mass spectrometry (GC–MS/MS). The extraction parameters such as the extraction solvent, the temperature and the time of extraction, and the addition of salt were optimized by means of experimental design tools. Selected conditions were 100μL of chloroform, 10mL of sample, 2g of salt (NaCl) and 5min of extraction. Good linearity (R2>0.9910), quantitative recoveries (>90% for most of compounds) and satisfactory precision (RSD<10% in most cases) were achieved under the optimal conditions. The methodology was successfully applied to the analysis of different types of water samples including seawater, spas, rivers, swimming pools, and aquaparks, in which most of the target compounds were found at concentrations sometimes over the part per million. Since no significant matrix effect has been found for any of the water types analyzed, quantification could be carried out by using conventional external calibration, thereby allowing a high analytical throughput and a valuable protocol simplification.

Determination of personal care products and hormones in leachate and groundwater from Polish MSW landfills by ultrasound-assisted emulsification microextraction and GC-MS.

Determination of the endocrine disrupting compounds (EDCs) in leachate and groundwater samples from the landfill sites is very important because of the proven harmful effects of these compounds on human and animal organisms. A method combining ultrasound-assisted emulsification microextraction (USAEME) and gas chromatography–mass spectrometry (GC-MS) was developed for simultaneous determination of seven personal care products (PCPs): methylparaben (MP), ethylparaben (EP), propylparaben (PP), buthylparaben (BP), benzophenone (BPh), 3-(4-methylbenzylidene)camphor (4-MBC), N,N-diethyltoluamide (DEET), and two hormones: estrone (E1) and β-estradiol (E2) in landfill leachate and groundwater samples. The limit of detection (LOD)/limit of quantification (LOQ) values in landfill leachate and groundwater samples were in the range of 0.003–0.083/0.009–0.277 μg L−1 and 0.001–0.015/0.002–0.049 μg L−1, respectively. Quantitative recoveries and satisfactory precision were obtained. All studied compounds were found in the landfill leachates from Polish municipal solid waste (MSW) landfills; the concentrations were between 0.66 and 202.42 μg L−1. The concentration of pollutants in groundwater samples was generally below 0.1 μg L−1.

Improved sensitivity gas chromatography–mass spectrometry determination of parabens in waters using ionic liquids

A new procedure for the introduction of ionic liquid samples in gas chromatography (GC) is proposed. This procedure, based on microvial insert thermal desorption, allows the direct analysis of the compounds preconcentrated by ionic liquid based liquid–liquid microextraction (IL-LLME) using the combination of a thermal desorption unit (TDU) and a programmed temperature vaporization injector (PTV). Two different IL-LLME methodologies, one based on the formation of a microdroplet emulsion by dispersive liquid–liquid microextraction (DLLME) and other through ultrasound-assisted emulsification microextraction (USAEME) were studied and evaluated. IL-DLLME proved advantageous and consequently, it was adopted for preconcentration purposes. This easy to apply approach was used for the determination of five parabens (methyl-, ethyl-, propyl-, butyl- and isobutyl paraben) in swimming pool waters, after in situ acetylation. The optimized conditions of TDU/PTV allowed the analytes contained in 20µL of the enriched IL to be transferred to the capillary column. Quantification of the samples was carried out against aqueous standards, and quantification limits of between 4.3 and 8.1ngL−1 were obtained, depending on the compound. Concentrations of between 9 and 47ngL−1 for some analytes were obtained in the analysis of ten samples.

A Simple Organic Solvent-Free Liquid-Liquid Microextraction Method for the Determination of Potentially Toxic Metals as 2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol Complex from Food and Biological Samples.

An organic solvent-free method was developed to extract some potentially toxic metals, as complexed with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol, from different real samples prior to their determination by microsampling flame atomic absorption spectrometry. The method, named ionic liquid-based ultrasound-enhanced air-assisted liquid-liquid microextraction (IL-USE-AALLME), is based upon withdrawing and pushing out a mixture of an aqueous sample and an IL (as the extraction solvent) for several times into a conical test tube using a single syringe, placed in an ultrasound bath (as the enhancing mass transfer agent) during the extraction process. Different effective parameters were studied, and at the optimized conditions, limits of detection, linear dynamic ranges, and enrichment factors were ranged from 0.9 to 2.2 μg L(-1), 3.0 to 1023 μg L(-1), and 20 ± 2 to 22 ± 2, respectively. After optimization, the method was successfully applied to determine Pb(2+), Cu(2+), Co(2+), Ni(2+), and Cr(3+) in different biological (hair and nail), vegetable (coriander, parsley, and tarragon), fruit juice (apple, orange, and peach), and water (tap, mineral, and wastewater) samples. The proposed method was compared with two other IL-based and disperser solvent-free methods (i.e., IL-based air-assisted liquid-liquid microextraction and IL-based ultrasound-assisted emulsification microextraction) to demonstrate its performance.

Ultrasound-assisted emulsification microextraction followed by gas chromatography–flame ionization detection for urinary methylmalonic acid determination

An efficient microextraction technique followed by gas chromatography–flame ionization detector (GC–FID) analysis was developed for determination of methylmalonic acid (MMA) concentration in human urine samples. This method was based on ultrasound-assisted emulsification microextraction followed by derivatization with a low density alcoholic solvent which performs both as an extraction solvent and as a derivatization agent, simultaneously. In this procedure, 80μL of 1-heptanol was injected slowly into a 10mL acidified aqueous sample of MMA placed inside an ultrasonic water bath. The resulting emulsion was centrifuged and after derivatization, 2μL of the organic phase was injected into a GC–FID. Several factors affecting the derivatization and the extraction were optimized. Under the optimal conditions, linearity was in the range of 1 to 250 and 3 to 200μmol/L corresponding to the limits of detection (LOD) 0.8 and 2.4μmol/L in water and urine samples, respectively. The inter-day and intra-day precision of the proposed method were evaluated in terms of the relative standard deviation (RSD), which were <11% (n=4). The proposed method presented an acceptable LOD for urinary MMA analysis with satisfactory RSD.

Chemometric-based determination of polycyclic aromatic hydrocarbons in aqueous samples using ultrasound-assisted emulsification microextraction combined to gas chromatography–mass spectrometry

In the present research, ultrasonic-assisted emulsification-microextraction (USAEME) coupled with gas chromatography–mass spectrometry (GC–MS) has been proposed for analysis of thirteen environmental protection agency (EPA) polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Tetrachloroethylene was selected as extraction solvent. The main parameters of USAEME affecting the efficiency of the method were modeled and optimized using a central composite design (CCD). Under the optimum conditions (9μL for extraction solvent, 1.15% (w/v) NaCl (salt concentration) and 10min for ultrasonication time), preconcentration factor (PF) of the PAHs was in the range of 500–950. In order to have a comprehensive analysis, multivariate curve resolution-alternating least squares (MCR-ALS) as a second-order calibration algorithm was used for resolution, identification and quantification of the target PAHs in the presence of uncalibrated interferences. The regression coefficients and relative errors (REs, %) of calibration curves of the PAHs were in the satisfactory range of 0.9971–0.9999 and 1.17–6.59%, respectively. Furthermore, analytical figures of merit (AFOM) for univariate and second-order calibrations were obtained and compared. As an instance, the limit of detections (LODs) of target PAHs were in the range of 1.87–18.9 and 0.89–6.49ngmL−1 for univariate and second-order calibration, respectively. Finally, the proposed strategy was used for determination of target PAHs in real water samples (tap and hookah waters). The relative recoveries (RR) and the relative standard deviations (RSDs) were 68.4–109.80% and 2.15–6.93%, respectively. It was concluded that combination of multivariate chemometric methods with USAEME-GC–MS can be considered as a new insight for the analysis of target analytes in complex sample matrices.

In situ emulsification microextraction using a dicationic ionic liquid followed by magnetic assisted physisorption for determination of lead prior to micro-sampling flame atomic absorption spectrometry

For the first time, a simple and efficient in situ emulsification microextraction method using a dicationic ionic liquid followed by magnetic assisted physisorption was presented to determine trace amounts of lead. In this method, 400 μL of 1.0 mol L−1 lithium bis (trifluoromethylsulfonyl) imide aqueous solution, Li[NTf2], was added into the sample solution containing 100 μL of 1.0 mol L−1 1,3-(propyl-1,3-diyl) bis (3-methylimidazolium) chloride, [pbmim]Cl2, to form a water immiscible ionic liquid, [pbmim][NTf2]2. This new in situ formed dicationic ionic liquid was applied as the acceptor phase to extract the lead-ammonium pyrrolidinedithiocarbamate (Pb-APDC) complexes from the sample solution. Subsequently, 30 mg of Fe3O4 magnetic nanoparticles (MNPs) were added into the sample solution to collect the fine droplets of [pbmim][NTf2]2, physisorptively. Finally, MNPs were eluted by acetonitrile, separated by an external magnetic field and the obtained eluent was subjected to micro-sampling flame atomic absorption spectrometry (FAAS) for further analysis. Comparing with other microextraction methods, no special devices and centrifugation step are required. Parameters influencing the extraction efficiency such as extraction time, pH, concentration of chelating agent, amount of MNPs and coexisting interferences were studied. Under the optimized conditions, this method showed high extraction recovery of 93% with low LOD of 0.7 μg L−1. Good linearity was obtained in the range of 2.5–150 μg L−1 with determination coefficient (r2) of 0.9921. Relative standard deviation (RSD%) for seven repeated measurements at the concentration of 10 μg L−1 was 4.1%. Finally, this method was successfully applied for determination of lead in some water and plant samples.

Ultrasound‐Assisted Emulsification‐Microextraction With In Situ Derivatization and Gas Chromatography‐Electron‐Capture Detection for Determination of Chlorophenols in Water

A new method, ultrasound‐assisted emulsification–microextraction (USAEME) with in situ derivatization and gas chromatography‐electron‐capture (GC‐μ‐ECD) detection, was developed to determine selected chlorophenols (CPs), including 2‐chlorophenol, 2,6‐dichlorophenol, 2,4,5‐trichlorophenol, 2,3,4,6‐tetrachlorophenol, and pentachlorophenol in water and wastewater samples. Initially the suitable solvent was determined and amount of derivatization reagent (acetic anhydride) and K2CO3, other experimental variables involving extraction and derivatization time, volume of extraction solvent and sample ionic strength, were optimized employing a 23 factorial experimental design. The developed method employed 100 μL of chloroform as extraction solvent, extraction with in situ derivatization for 10 min using 100 µL of acetic anhydride and 100 µL K2CO3 (5%, w/v) for 5 mL samples at 25°C with no ionic strength adjustment and centrifugation for 5 min at 4000 rpm. The average relative recoveries under optimum conditions were &gt;97% with relative standard deviation (RSD) ≤5% for three different spiking levels (5, 20, and 100 μg L‐1). The limits of detection for studied CPs were in the range of 0.007–0.011 μg L−1. The developed USAEME with in situ derivatization method was successfully applied to real water samples such as tap, dam water, and domestic wastewater. The developed method showed comparable efficiency with conventional liquid–liquid extraction‐derivatization coupled with GC‐μ‐ECD. The results demonstrated that the developed USAEME with in situ derivatization is simple, fast and reliable for determination of selected CPs in water samples by GC‐μ‐ECD.

Application of an Ultrasound-assisted Polymer Surfactant-enhanced Emulsification Microextraction for Determination of Aromatic Amines in Water Sample

A simple and efficient method, based on ultrasound-assisted polymer surfactant-enhanced emulsification microextraction (SA-USAEME) followed by gas chromatography-mass spectrometry (GC-MS), has been developed for the determination of eight aromatic amines (AAs) in aqueous sample. The main parameters affecting the performance of the proposed method were optimized, and the optimum conditions were obtained as follows: 150 μL of extractive solvent (dichloroethane) 150 μL, polymer surfactant (sodium alginate) of 0.20 g L−1, pH 7.0, salt addition of 3%, and ultrasound time of 1 min. Under the optimal conditions, the linear ranges were 0.1-200 μg L−1 for 3,3′-dichlorobenzidine, 0.3-200 μg L−1 for 2,4,5-trime concentration thylaniline, 4-chloro-o-toluidine, 3,3′-dimethyl-4,4′-diaminodiphenylmethane, 3,3′-dimethylbenzidine and 4,4′-methylene-bis-(2-chloroaniline), and 0.5-200 μg L−1 for 4-aminoazobenzene and 3,3′-dimethoxybenzidine. The correlation coefficients (R2) and detection limits were 0.9961-0.9997 and 0.08-0.3 μg L−1 respectively. The intra- and inter-RSD were less than 10.3% and 11.9%. Additionally, the proposed method could be applied to the analysis of AAs in water sample respectively collected from tap water and river water. Compared with the common SA-USAEME, conventional surfactant was replaced with water-soluble polymer surfactant in this method to solve the problems of potential pollution and decrease the GC limitation since the polymer surfactant were natural and insoluble in extractive solvent. Compared with solid phase extraction, the proposed method enjoyed simplicity of operation and low cost. Therefore, it is an alternative method that could be widely used for the analysis of trace level of AAs in water sample.

Comparison of air-agitated liquid-liquid microextraction and ultrasound-assisted emulsification microextraction for polycyclic aromatic hydrocarbons determination in hookah water.

In this work, two disperser-free microextraction methods, namely, air-agitated liquid-liquid microextraction and ultrasound-assisted emulsification microextraction are compared for the determination of a number of polycyclic aromatic hydrocarbons in aqueous samples, followed by gas chromatography with flame ionization detection. The effects of various experimental parameters upon the extraction efficiencies of both methods are investigated. Under the optimal conditions, the enrichment factors and limits of detection were found to be in the ranges of 327-773 and 0.015-0.05 ng/mL for air-agitated liquid-liquid microextraction and 406-670 and 0.015-0.05 ng/mL for ultrasound-assisted emulsification microextraction, respectively. The linear dynamic ranges and extraction recoveries were obtained to be in the range of 0.05-120 ng/mL (R(2) ≥ 0.995) and 33-77% for air-agitated liquid-liquid microextraction and 0.05-110 ng/mL (R(2) ≥ 0.994) and 41-67% for ultrasound-assisted emulsification microextraction, respectively. To investigate this common view among some people that smoking hookah is healthy due to the passage of smoke through the hookah water, samples of both the hookah water and hookah smoke were analyzed.

Determination of Herbicides in Milk Using Vortex-Assisted Surfactant-Enhanced Emulsification Microextraction Based on the Solidification of a Floating Organic Droplet

A vortex-assisted surfactant-enhanced emulsification–solidification liquid microextraction (VASEME-SFO) has been proposed for the determination of triazine and phenylurea herbicides in milk. 1-Dodecanol was used as the extraction solvent and dispersed into the aqueous samples by the assistance of a vortex mixer. Meanwhile, the addition of a surfactant, which was used as an emulsifier, could enhance the speed of the mass transfer from aqueous samples to the extract solvent. Acetic acid and Na2SO4 were applied and used to eliminate interference by proteins and fats. The influence of various parameters in the VASEME-SFO such as the type and volume of the extraction solvent, the type and concentration of the surfactant, and the vortex time, salt addition, and sample solution pH were investigated and optimized. Under optimal conditions, the limits of detection (LODs) and quantification (LOQs) reached ranges of 0.005–0.09 and 0.015–0.30 μg L−1, respectively. Dynamic linear ranges (DLRs) of 0.2–200 and 2–400 μg L−1 were obtained for triazine and phenylurea herbicides, respectively. The performance of the method was evaluated for extraction and determination of these herbicides in milk in micrograms per liter, and satisfactory results were obtained (RSD < 10.6 %).

Evaluation of the contamination of spirits by polycyclic aromatic hydrocarbons using ultrasound-assisted emulsification microextraction coupled to gas chromatography–mass spectrometry

The concentration of twelve polycyclic aromatic hydrocarbons (PAHs), included in the list of priority pollutants, in different spirits has been obtained by means of a rapid and sensitive method based on gas chromatography and mass spectrometry (GC–MS). The environmentally friendly ultrasound-assisted emulsification microextraction (USAEME) technique allowed the easy and effective preconcentration of the PAHs from the sample matrices. Several parameters affecting the extraction efficiency, such as the nature and volume of the extractant solvent, and the addition of salt, as well as the sonication parameters were investigated and optimized. The absence of matrix effects under the optimized conditions allowed the sample quantification against aqueous standards. Detection limits ranged between 1.8 and 6.3ngL−1, depending on the compound. Different spirit samples were successfully analyzed using the proposed method, and contents of up to 0.9μgL−1 were found. Relative recoveries at fortified levels of 0.2 and 1μgL−1 were in the range 84–118%.

Monitoring of pyridine, 3-picoline and quinoline in smokers’ urine using ultrasound-assisted emulsification microextraction coupled with high-performance liquid chromatography

The present work describes application of ultrasound-assisted emulsification microextraction (USAEME) method for simultaneous determination of pyridine, 3-picoline and quinoline followed by high-performance liquid chromatography in smokers’ urine samples. For this purpose, the influences of different parameters affecting the USAEME procedure were evaluated to optimize the efficiency of the microextraction process. The optimum conditions were found to be 50 µL of 1-hexanol as extraction solvent as well as ionic strength of 15 % (w/v) NaCl. Under the optimum extraction conditions, the preconcentration factors were found in the range of 60–270 and 50–230 corresponding to the limits of detection in the range of 0.1–16 and 0.5–32 μg L−1 in water and urine samples, respectively. Finally, the proposed method was successfully applied for the determination of pyridine derivatives in some urine samples taken from cigarette smokers.