Dispersive Liquid-liquid Microextraction Technique Research Articles

Bioanalysis of a panel of neurotransmitters and their metabolites in plasma samples obtained from pediatric patients with neuroblastoma and Wilms' tumor

This paper details the quantitative analysis of neurotransmitters, including dopamine (DA), norepinephrine (NE), epinephrine (E), and serotonin (5-HT), along with their respective precursors and metabolites in children with solid tumors: Wilms' tumor (WT) and neuroblastoma (NB). A panel of neurotransmitters was determined with the use of dispersive liquid-liquid microextraction (DLLME) technique combined with liquid-chromatography mass spectrometry (LC-MS/MS) in plasma samples obtained from a group of pediatric subjects with solid tumors and a control group of healthy children. Next, statistical univariate analysis (t-test) and multivariate analysis (Principal Component Analysis) were performed using chromatographic data. The levels of tyrosine (Tyr) and tryptophan (Trp) (the precursors of analyzed neurotransmitters) as well as 3,4-dihydroxyphenylacetic acid (DOPAC) (a product of metabolism of DA) were significantly higher in the plasma samples obtained from pediatric patients with WT than in the samples taken from the control group. Moreover, statistically significant differences were observed between the levels of 5-HT and homovanillic acid (HVA) in the plasma samples from pediatric patients with solid tumors and the control group. However, elevated levels of these analytes did not facilitate a clear distinction between pediatric patients with WT and those with NB. Nonetheless, the application of advanced statistical tools allowed the healthy controls to be differentiated from the pediatric oncological patients. The identification and quantification of a panel of neurotransmitters as potential prognostic factors in selected childhood malignancies may provide clinically relevant information about ongoing metabolic alterations, and it could potentially serve as an adjunctive strategy in the effective diagnosis and treatment of solid tumors in children.

Fast, sensitive and reliable multi-residue method for routine determination of 34 pesticides from various chemical groups in water samples by using dispersive liquid\u2013liquid microextraction coupled with gas chromatography\u2013mass spectrometry

A simple and efficient dispersive liquid-liquid microextraction technique (DLLME) was developed by using a mixture of two solvents: 40 μL of tetrachlorethylene (extraction solvent) and 1.0 mL of methanol (disperser solvent), which was rapidly injected with a syringe into 10 mL of water sample. Some important parameters affecting the extraction efficiency, such as type and volume of solvents, water sample volume, extraction time, temperature, pH adjustment and salt addition effect were investigated. Simultaneous determination of 34 commonly used pesticides was performed by using gas chromatography coupled with mass spectrometry (GC-MS). The procedure has been validated in order to obtain the highest efficiency at the lowest concentration levels of analytes to fulfill the requirements of regulations on maximum residue limits. Under the optimum conditions, the linearity range was within 0.0096–100 μg L−1. The limits of detection (LODs) of the developed DLLME-GC-MS methodology for all investigated pesticides were in the range of 0.0032 (endrin)–0.0174 (diazinon) μg L−1 and limits of quantification (LOQs) from 0.0096 to 0.052 μg L−1. At lower concentration of 1 μg L−1 for each pesticide, recoveries ranged between 84% (tebufenpyrad) and 108% (deltamethrin) with relative standard deviations (RSDs) (n = 7) from 1.1% (metconazole) to 11% (parathion-mehtyl). This methodology was successfully applied to check contamination of environmental samples. The procedure has proved to be selective, sensitive and precise for the simultaneous determination of various pesticides. The optimized analytical method is very simple and rapid (less than 5 min).Graphical abstractAnalytical procedure for testing water samples consists of dispersive liquid-liquid microextraction (DLLME) and gas chromatography coupled with mass spectrometry (GC-MS).

A novel task specific magnetic polymeric ionic liquid for selective preconcentration of potassium in oil samples using centrifuge-less dispersive liquid-liquid microextraction technique and its determination by flame atomic emission spectroscopy

In the present study a new centrifuge-less dispersive liquid-liquid microextraction technique based on application of a new task specific magnetic polymeric ionic liquid (TSMPIL) as a chelating and extraction solvent for selective preconcentration of trace amounts of potassium from oil samples is developed, for the first time. After extraction, the fine droplets of TSMPIL were transferred into an eppendorf tube and diluted to 500µL using distilled water. Then, the enriched analyte was determined by flame atomic emission spectroscopy (FAES). Several important factors affecting both the complexation and extraction efficiency including extraction time, rate of vortex agitator, amount of carbonyl iron powder, pH of sample solution, volume of ionic liquid as well as effects of interfering species were investigated and optimized. Under the optimal conditions, the limits of detection (LOD) and quantification (LOQ) were 0.5 and 1.6µgL−1 respectively with the preconcentration factor of 128. The precision (RSD %) for seven replicate determinations at 10µgL−1 of potassium was better than 3.9%. The relative recoveries for the spiked samples were in the acceptable range of 95–104%. The results demonstrated that no remarkable interferences are created by other various ions in the determination of potassium, so that the tolerance limits (WIon/WK) of major cations and anions were in the range of 2500–10,000. The purposed method was successfully applied for the analysis of potassium in some oil samples.

Determination of parabens using two microextraction methods coupled with capillary liquid chromatography-UV detection

Parabens are common preservatives and environmental hormones. As such, possible detrimental health effects could be amplified through their widespread use in foods, cosmetics, and pharmaceutical products. Thus, the determination of parabens in such products is of particular importance. This study explored vortex-assisted dispersive liquid-liquid microextraction techniques based on the solidification of a floating organic drop (VA-DLLME-SFO) and salt-assisted cloud point extraction (SA-CPE) for paraben extraction. Microanalysis was performed using a capillary liquid chromatography-ultraviolet detection system. These techniques were modified successfully to determine four parabens in 19 commercial products. The regression equations of these parabens exhibited good linearity (r2=0.998, 0.1–10μg/mL), good precision (RSD<5%) and accuracy (RE<5%), reduced reagent consumption and reaction times (<6min), and excellent sample versatility. VA-DLLME-SFO was also particularly convenient due to the use of a solidified extract. Thus, the VA-DLLME-SFO technique was better suited to the extraction of parabens from complex matrices.

A dispersive liquid–liquid microextraction based on solidification of floating organic drop and spectrophotometric determination of uranium in breast milk after optimization using Box-Behnken design

A new procedure developed based on a preconcentration system using a dispersive liquid-liquid microextraction technique based on solidification of floating organic drop (DLLME-SFO) was combined with the molecular absorption spectrometry to determine uranium using 2-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (Br-PADAP) as the complexing reagent. The optimization step was performed using two-level factorial design and the Box-Behnken design. The parameters analyzed were pH, Br-PADAP volume, extractant solvent volume and disperser solvent volume. The method allowed determining uranium with a limit of detection of 0.46μgL−1, limit of quantification 1.53μgL−1. The enrichment factor was estimated to be 76-fold. The precision expressed as relative standard deviation (RSD) for uranium concentrations of 2 and 10μgL−1 was 4.91% and 1.85% (n=15), respectively. Accuracy was assessed using recovery values ranging from 95.28% to 103.86%, which proves that this method does not suffer from a matrix effect and can be satisfactorily applied. The proposed method was applied to determine uranium in human milk samples. Fifteen samples were analyzed, and the uranium concentration ranged from 45.87±3.62μgL−1 to 160.97±7.00μgL−1.

Simultaneous determination of pyrethroids and pyrethrins by dispersive liquid-liquid microextraction and liquid chromatography triple quadrupole mass spectrometry in environmental samples.

A simple and environmentally friendly dispersive liquid-liquid microextraction (DLLME) method coupled with electrospray ionization liquid chromatography triple quadrupole mass spectrometry (LC-QqQ-MS/MS) was developed for the simultaneous determination of 17 synthetic and natural pyrethroids. A comparison of solid-phase extraction (SPE) versus DLLME for water samples and only "dilute and shoot" versus the additional extract cleanup by DLLME for sediment samples is reported. Chloroform was the extracting solvent in the DLLME technique for both water and sediment samples. Ultrasonic energy was applied to fully extract the analytes into fine droplets, providing high recoveries in short times. Method detection limits (MDLs) ranged from 0.12 to 0.62ngL-1 and recoveries from 70 to 119% with RSD values 2-15% (n=5) for water samples. In sediment samples, MDLs ranged from 0.50 to 2.50ngg-1 and recoveries from 71 to 112% with RSDs 2-16% (n=5). The proposed method showed a good linearity within the range of 10-500ngmL-1, with coefficients of determination (R 2) higher than 0.99. Matrix effects were observed for most compounds in water and sediment (ME%<-10%). The proposed methodology was applied for the analysis of water and sediment samples from Albufera wetland and Turia River. Acrinathrin (48ngg-1) and etofenprox (16ngg-1) were detected in sediment samples. Graphical abstract Pyrethrins and pyrethroid determination in water and sediments by DLLME and LC-MS/MS.

Preconcentration and determination of 2-mercaptobenzimidazole by dispersive liquid-liquid microextraction and experimental design.

A method was developed to determine 2-mercaptobenzimidazole in water and urine samples using dispersive liquid-liquid microextraction technique coupled with ultraviolet-visible spectrophotometry. It was essential to peruse the effect of all parameters that can likely influence the performance of extraction. The influence of parameters, such as dispersive and extraction solvent volume and sample volume, on dispersive liquid-liquid microextraction was studied. The optimization was carried out by the central composite design method. The central composite design optimization method resulted in 1.10mL dispersive solvent, 138.46μL extraction solvent, and 4.46mL sample volume. Under the optimal terms, the calibration curve was linear over the range of 0.003-0.18 and 0.007-0.18μg/mL in water and urine samples, respectively. The limit of detection and quantification of the proposed approach for 2-mercaptobenzimidazole were 0.013 and 0.044μg/mL in water samples and 0.016 and 0.052μg/mL in urine samples, respectively. The method was successfully applied to determination of 2-mercaptobenzimidazole in urine and water samples.

Centrifugeless dispersive liquid-liquid microextraction based on salting-out phenomenon as an efficient method for determination of phenolic compounds in environmental samples.

A new centrifugeless dispersive liquid-liquid microextraction (DLLME) method was applied for the convenient extraction of some phenolic compounds from environmental samples. After dispersing the extracting solvent into the sample solution (10.0mL), the mixture was passed through a small column filled with 5g sodium chloride. As a result, phase separation was achieved via the salting-out phenomenon, and the extracting solvent was suspended on top of the sample solution. Using a low-toxic and solidifiable extracting solvent (1-dodecanol), after immersing the column into an ice bath, the extracting solvent was solidified, collected easily, and injected into an HPLC-UV instrument. The overall extraction time was 7min, consumption of the extracting solvent was efficiently reduced to 50μL, and the centrifugation step was simply eliminated, which made the automation of the procedure easier than the normal DLLME technique. A series of parameters influencing the extraction were investigated systematically. The optimal experimental conditions were found to be 50μL of 1-dodecanol as the extracting solvent, a flow rate of 2.0mLmin-1, and a pH value of 4.0 for the sample solution. Under these conditions, the method provided a good linearity in the range of 0.5-800ngmL-1, low limits of detection (0.1-0.3ngmL-1), good extraction repeatabilities (RSDs below 9.1%, n = 5), and enrichment factors of 100-160. Graphical Abstract Schematic diagram of the centrifugeless dispersive liquid-liquid microextraction.

Development and Validation of a LC-ESI-MS/MS Method for the Determination of Alternaria Toxins Alternariol, Alternariol Methyl-Ether and Tentoxin in Tomato and Tomato-Based Products.

Alternaria species are capable of producing several secondary toxic metabolites in infected plants and in agricultural commodities, which play important roles in food safety. Alternaria alternata turn out to be the most frequent fungal species invading tomatoes. Alternariol (AOH), alternariol monomethyl ether (AME), and tentoxin (TEN) are some of the main Alternaria mycotoxins that can be found as contaminants in food. In this work, an analytical method based on liquid chromatography (LC) tandem mass spectrometry (MS/MS) detection for the simultaneous quantification of AOH, AME, and TEN in tomato and tomato-based products was developed. Mycotoxin analysis was performed by dispersive liquid-liquid microextraction (DLLME) combined with LC-ESI-MS/MS. Careful optimization of the MS/MS parameters was performed with an LC/MS system with the ESI interface in the positive ion mode. Mycotoxins were efficiently extracted from sample extract into a droplet of chloroform (100 µL) by DLLME technique using acetonitrile as a disperser solvent. Method validation following the Commission Decision No. 2002/657/EC was carried out by using tomato juice as a blank matrix. Limits of detection and quantitation were, respectively, in the range 0.7 and 3.5 ng/g. Recovery rates were above 80%. Relative standard deviations of repeatability (RSDr) and intermediate reproducibility (RSDR) were ≤ 9% and ≤ 15%, respectively, at levels of 25 and 50 ng/g. Five out of 30 analyzed samples resulted positive to at least one Alternaria toxin investigated. AOH was the most common Alternaria toxin found, but at levels close to LOQ (average content: 3.75 ng/g).

Towards coupling dispersive liquid-liquid microextraction with hollow fibre liquid phase microextraction for extraction of organic pollutants of agricultural origin

Liquid-based miniaturized techniques have received a lot of attention recently resulting in the development of the liquid phase microextraction (LPME) and dispersive liquid-liquid microextraction (DLLME) techniques each offering unique benefits over the other technique. Herein we report a combination of the two techniques for the extraction of hexestrol and atrazine from aqueous systems. The method sets off with the DLLME thereafter a hollow fibre filled with the organic solvent is introduced for the extraction of the pre-extracted analytes in the dispersed organic solvent. The method was modified further by introducing a second extracting solvent in place of the disperser solvent. Under the optimum conditions, namely, toluene in the acceptor phase, 1:1 chloroform:toluene (v/v) as a dispersed solvent, 15% NaCl, with the 15 min extraction time, the method achieved satisfactory enrichment factors (87- and 62-fold); sufficiently low detection limits of 0.018 μg/mL and 0.016 μg/mL using the flame ionization detector, while 0.072 and 0.063 ng/mL were obtained using single ion monitoring mass spectrometry detector, for atrazine and hexestrol, respectively; with sufficient linearity (R2 ≥ 0.9959). Although the compounds were not detected in the river water sample, satisfactory recoveries (111–115%) were achieved indicating the method did not suffer any negative matrix effect.

ChemInform Abstract: A Critical Overview on the Chemistry, Clean‐Up and Recent Advances in Analysis of Biogenic Amines in Foodstuffs

AbstractReview: 100 refs.

Development of a dispersive liquid-liquid microextraction technique for the analysis of aryloxyphenoxy-propionate herbicides in soy-based foods

In this work, an ionic liquid–dispersive liquid-liquid microextraction (IL-DLLME) method combined with liquid chromatography and diode-array detection (DAD) was used for the determination of four aryloxyphenoxy-propionate herbicides (fenoxaprop-p-ethyl, quizalofop-p-tefuryl, propaquizafop and haloxyfop-p-methyl) in two soy-based foods (soy milk and soy sauce) was used. For this purpose, the phosphonium-based room temperature ionic liquid (trihexyl(tetradecyl)phosphonium bistriflamide) was used as the extractant. The effect of the experimental parameters on extraction efficiency such as type of disperser solvent, disperser solvent/ ionic liquid volumes ratio, pH, nature and concentration of salt in the aqueous phase, sample volume, and centrifugation and extraction times were investigated and optimized. Since matrix effects were detected, the standard addition method was used for quantification. Under the optimized conditions, the proposed sample preparation method coupled to high performance liquid chromatography-diode array detection (HPLC-DAD) had a satisfactory performance to determine the four herbicides in soy sauce and soy milk. The enrichment factors ranged from 18 to 43 and recovery factors from 25 to 66%. Although the recoveries were not high because of the presence of organic solvent in the sample preparation step, the inter-day reproducibility was 8.4% or less, depending on the analyte, the limits of detection (S/N=3) were obtained in the range of 0.12–0.34mgL−1, the limits of quantification (S/N=10) between 0.36 and 1.04mgL−1, and linear ranges from LOQs to 9.26mgL−1. Finally, the IL-DLLME methodology is inexpensive, simple, fast, and environmentally friendly for the determination of the studied herbicides in soy sauce and soy milk. This study constitutes the first application of an IL-DLLME methodology to aryloxyphenoxy-propionate herbicides analysis in commercial soy-derived foods.

Sensitive spectrophotometric determination of Co(II) using dispersive liquid-liquid micro-extraction method in soil samples.

Analytical performance of conventional spectrophotometer was developed by coupling of effective dispersive liquid-liquid micro-extraction method with spectrophotometric determination for ultra-trace determination of cobalt. The method was based on the formation of Co(II)-alpha-benzoin oxime complex and its extraction using a dispersive liquid-liquid micro-extraction technique. During the present work, several important variables such as pH, ligand concentration, amount and type of dispersive, and extracting solvent were optimized. It was found that the crucial factor for the Co(II)-alpha benzoin oxime complex formation is the pH of the alkaline alcoholic medium. Under the optimized condition, the calibration graph was linear in the ranges of 1.0-110 μg L(-1) with the detection limit (S/N = 3) of 0.5 μg L(-1). The preconcentration operation of 25 mL of sample gave enhancement factor of 75. The proposed method was applied for determination of Co(II) in soil samples.

A Microextraction Method Based on Ligandless Ion-Pair Formation for Measuring the Cadmium Cation in Real Samples by Flame Atomic Absorption Spectrometry

A new, simple, and ligandless ion-pair microextraction method has been developed for preconcentration and determination of cadmium ion in saline solutions and food samples. This technique is based on using a double chain cationic surfactant called didodecyldimethylammonium bromide (DDAB) as an ion-pairing agent and extraction solvent combined with dispersive microextraction named supramolecule aggregate-based dispersive liquid-solid microextraction (SA-DLSME) prior to aspiration to flame atomic absorption spectrometer. The Cd2+ ion interacts with chloride ion in saline solution, and the resulting anionic complex is microextracted by cationic supramolecule aggregates of DDAB due to electrostatic interaction. This technique benefits the advantages of supramolecule aggregate properties and dispersive liquid-liquid microextraction technique without the use of any dispersing solvent. Phase separation behavior of DDAB and several effective parameters that have influence on extraction efficiency of cadmium ion such as pH, salt concentration, centrifugation time, and DDAB amount were thoroughly investigated and optimized. Under the optimized experimental conditions, the limit of detection (LOD) and linear range were 1.3 and 5–250 ng mL−1, respectively, with relative standard deviations (RSD) in the range of 3.1–4.3 for interday analysis and 4.5–5.5 for intraday tests at different concentrations of cadmium. The proposed method was successfully applied for the determination of cadmium ion in real samples, and its accuracy was confirmed by analysis of a certified reference material.

Application of Air-Assisted Liquid-Liquid Microextraction for Determination of Some Fluoroquinolones in Milk Powder and Egg Samples: Comparison with Conventional Dispersive Liquid-Liquid Microextraction

Herein, an air-assisted liquid-liquid microextraction (AALLME) has been described and compared to conventional dispersive liquid-liquid microextraction (DLLME) for the extraction/preconcentration of six fluoroquinolone compounds in milk powder and egg samples prior to high-performance liquid chromatography-UV detection (HPLC-UV). In order to compare the novel AALLME technique to the conventional DLLME technique, several parameters that influence the extraction efficiency were studied and optimized. Both methods have been validated for milk powder and egg analysis, obtaining limits of quantification lower than those usually permitted by legislation in food matrices, with precisions expressed as coefficients of variation lower than 8 % and recoveries between 72 and 115 % which were acceptable recoveries and repeatability. An AALLME method needs less organic solvent and shorter centrifugation time; therefore, it is more environmentally friendly and efficiently compared to DLLME.

Ultra-Trace Determination of Co (ІІ) in Real Samples Using Ion Pair-Based Dispersive Liquid-Liquid Microextraction Followed by Electrothermal Atomic Absorption Spectrometry

Ion pair-based dispersive liquid-liquid microextraction technique was used for preconcentration and determination of ultra-trace levels of Co (ІІ) followed by electrothermal atomic absorption spectrometry (ETAAS). Thiocyanate (SCN−) forms an anionic complex with Co (ІІ) followed by addition of cetylpyridinium chloride (CPC) as a positive counterion to produce hydrophobic cobalt-thiocyanate-CPC complex. The resulting hydrophobic complex was extracted into the fine droplets of carbon tetrachloride by dispersive liquid-liquid microextraction (DLLME). In DLLME, a mixture of 1.5 mL of acetone (as disperser solvent) containing 40 μL of carbon tetrachloride (as extraction solvent) was rapidly injected into the sample solution to extract the hydrophobic cobalt-thiocyanate-CPC complex. Under the optimum conditions, the calibration curve was linear in the range of 0.08–1.5 μg L−1 of Co (ІІ) with a correlation coefficient of 0.9997. The relative standard deviation (RSD, %) based on six replicate analyses of 0.5 μg L−1 of Co (ІІ) was 3.7 %, and the limit of detection (LOD) was 0.02 μg L−1. The accuracy of the proposed method was evaluated by the analysis of a certified reference material and spike method. The proposed method was successfully applied for determination of ultra-trace levels of Co (ІІ) in different water samples and spinach leaves.

Development of coupled ultrasound-assisted and reversed-phase dispersive liquid-liquid microextraction before high-performance liquid chromatography for the sensitive determination of vitamin A and vitamin E in oil samples.

A new approach based on the ultrasound-assisted reversed-phase dispersive liquid-liquid microextraction technique is developed for the extraction and determination of vitamin A and vitamin E from oil matrices before high-performance liquid chromatography analysis. A methodology based on the full factorial design is carried out to choose the significant parameters. Then the significant factors affecting the extraction efficiency including pH, volume of extraction solvent, and volume of disperser solvent are optimized using a Box-Behnken design. After analyzing the results obtained, the optimum conditions were: pH 4.5, 80-20 μL of the ethanol/water solvent mixture as extraction solvent, 110 μL of 1,4-dioxane as the disperser solvent, and a sonication time of 10 min. For validation of the developed method, the linear dynamic range, repeatability, limit of detection, and recoveries were obtained under the optimum conditions. The detection limits of the method were 1.6 and 2.3 ng/mL for vitamin A and vitamin E, respectively. The extraction recovery percentages for the studied drugs were above 91%, with acceptable relative standard deviation. The proposed methodology was successfully applied for the determination of the vitamins in different oil samples.

Dispersive Liquid-Liquid Microextraction for the Determination of Emerging Fusarium Mycotoxins in Water

A new method was optimized for the determination of emerging Fusarium mycotoxins enniatins (ENs) and beauvericin (BEA) in different types of water. Mycotoxin analysis was performed by dispersive liquid-liquid microextraction (DLLME) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Mycotoxins were efficiently extracted from water into carbon tetrachloride by DLLME technique using acetonitrile as disperser solvent. Detection limits were in the range of 0.06–0.17 μg L−1. Quantification was performed using matrix-matched calibration curves over a linear range from limit of quantification (LOQ) to 200 μg L−1. Acceptable recoveries were obtained between 78.5 and 100.1 % with relative standard deviations of <14 %. The proposed method may be advised as an easy, sensitive, and accurate method for determining emerging Fusarium mycotoxins in water. The method was successfully applied to the analysis of different kinds of water. No detectable levels were achieved in surface, ground, tap, and bottled water. Concentration levels up to 50 μg L−1 were detected in cooking water related to the pasta cooking process.

Trace determination of lead in lipsticks and hair dyes using microwave-assisted dispersive liquid-liquid microextraction and graphite furnace atomic absorption spectrometry.

A novel microwave-assisted dispersive liquid-liquid microextraction (MADLLME) technique according to the solidification of a floating organic droplet (SFO) and graphite furnace atomic absorption spectrometry (GFAAS) used for the extraction and determination of lead ions in lipsticks and hair dyes made in different countries. Lipstick and hair dye samples of different brands and colours were collected from local market in Kermanshah, Iran. After sample treatment with microwave-assisted acid digestion, an appropriate mixture of acetone, 1-undecanol and diethyl dithiophosphoric acid was injected rapidly into the aqueous sample containing lead ions, and as a result, cloudy mixture was formed. After centrifugation, the test tube was cooled for few minutes. The solidified 1-undecanol on top of the solution was transferred into a suitable vial and injected into the analytical instrument. Under the optimum experimental conditions (extraction solvent: 30μL of 1-undecanol; disperser solvent: 500μL of acetone; ligand concentration: 0.15% (v/v); pH: ~1.5 and without salt added), the enhancement factor of 96 was obtained. The calibration graphs were linear in the range of 0.3-50μgkg(-1) with a correlation coefficient (r(2) ) more than 0.995. The detection limit was 0.1μgkg(-1) . Consequently, the developed method was successfully applied to extract and determine lead ions in the lipsticks and hair dyes, and favourable results were obtained. The proposed method which applied in cosmetics showed excellent relative recoveries (90-109.7%) with relative standard deviations <8.3% (n=3) for all samples. The study revealed that the concentration of lead found in lipsticks and hair dyes on the Kermanshah market is far below the recommended limits as applied in Germany (20mg kg(-1) ) and Canada (10mg kg(-1) ) and confirmed that very low levels of lead are technically available in the final cosmetic products.

Accelerated solvent extraction combined with dispersive liquid-liquid microextraction before gas chromatography with mass spectrometry for the sensitive determination of phenols in soil samples.

A method combining accelerated solvent extraction with dispersive liquid-liquid microextraction was developed for the first time as a sample pretreatment for the rapid analysis of phenols (including phenol, m-cresol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol) in soil samples. In the accelerated solvent extraction procedure, water was used as an extraction solvent, and phenols were extracted from soil samples into water. The dispersive liquid-liquid microextraction technique was then performed on the obtained aqueous solution. Important accelerated solvent extraction and dispersive liquid-liquid microextraction parameters were investigated and optimized. Under optimized conditions, the new method provided wide linearity (6.1-3080 ng/g), low limits of detection (0.06-1.83 ng/g), and excellent reproducibility (<10%) for phenols. Four real soil samples were analyzed by the proposed method to assess its applicability. Experimental results showed that the soil samples were free of our target compounds, and average recoveries were in the range of 87.9-110%. These findings indicate that accelerated solvent extraction with dispersive liquid-liquid microextraction as a sample pretreatment procedure coupled with gas chromatography and mass spectrometry is an excellent method for the rapid analysis of trace levels of phenols in environmental soil samples.