Phthalate esters (PAEs) are highly susceptible to leaching from plastic packaging into food products during processing, transport, and storage. Therefore, in this study, a newly synthesized sorbent material, phosphate-MIL-101(Cr)-NH2/ polysulfone (PSF) porous beads, was introduced into a pipette tip micro-solid phase extraction coupled to HPLC-PDA for the quantification of six PAEs from food matrices. The porous beads effectively address the issue of the excessive backpressure in PT-μSPE, improve the reproducibility and stability of the adsorbent, and serve as an efficient adsorbent. Key experimental factors affecting extraction efficiency were optimized using a response surface methodology (RSM) model using central composite design (CCD). The synthesized porous sorbent material was characterized by SEM, TGA, EDS, FTIR, XRD, and N2 phosphate functionality to the MIL-101(Cr)-NH2 adsorption analysis. The addition of particles and polyvinylpyrrolidone (PVP) to polysulfone increases the extraction efficiency of the adsorbent and the porosity of the polymer. This method shows a reliable, rapid, and efficient approach with satisfactory EF, low LOD (0.3-4.0μg/L), linearity range of (1.0-250.0 and good precision RSD (1.2-4.3 %) in milk, PET bottled water, and juice.

Traditional microextraction methods, such as micro-solid-phase extraction ( μ SPE) and conventional fiber-based SPME, suffer from complexity, long extraction times, and insufficient surface area, resulting in poor sensitivity for trace-level pesticide analysis. To address these limitations, for the first time, MIL-53(Al) metal-organic framework as a thin-film (TF) was synthesized directly on an aluminum thin sheet for the determination of three insecticides (thiacloprid, imidacloprid, and acetamiprid). To enhance the adsorbent amount, a 25*35 mm of MIL- 53(Al)/Al thin sheet was rolled and placed in a pipette tip. The present approach offers significant advantages: enhanced surface area and rapid extraction in 15 min, and ease of use without the risk of clogging and back pressure in pipette tip μ SPE. Response surface methodology optimization established optimal conditions at pH 6.5 and 50.0 mL sample volume. The TF-MOF-HPLC method achieved superior analytical performance with detection limits of 0.3–1.5 μ and 5.0–450.0 μ g/L and quantification limits of 1.0–5.0 μ g/L. Linear ranges of 1.0–300.0, 3.0–350.0, g/L were obtained for acetamiprid, thiacloprid, and imidacloprid, respectively (R 2 >0.95). The target insecticides were subsequently extracted from cucumber samples by ultrasonic extraction using only 1.4 mL of acetonitrile and pre-concentrated using the TF-MOF microextraction method. Method validation in water, cucumber, and juice samples demonstrated excellent recovery rates (86.0–100.7%) with good precision (relative standard deviation) ≤ 3.3%. These results indicate that the developed TF-MIL-53(Al) method is a simple, rapid, and highly sensitive alternative to conventional microextraction methods for environmental and food safety monitoring.

Background: In this research, for the first time combination of ultrasound-assisted extraction and thin film micro-solid phase extraction (UAE-TF-μSPE) was developed, and applied to extract the acetamiprid and thiacloprid from foods. This procedure was shaped to resolving the analytical challenges that arise from analyzing food samples that display matrix effects on analyte recovery. Here, UAE extracts analytes from food matrices using less extraction solvent and is then coupled with TF-μSPE, where the latter performs clean-up and preconcentration of the target compound. NH2-MIL-101(Cr) was synthesized through hydrothermal method, embedded in a polysulfone thin film, and utilized as an adsorbent in μSPE technique. Results: The optimization of factor affecting of procedure was established based on response surface methodology (RSM). The critical parameters, such as pH, volume of extraction solvent, and ultrapure water volume were optimized. The method demonstrated outstanding analytical performance, with a detection limit established at 0.2 μg kg 1, a linearity range of (1.0-200.0) μg kg 1, very good repeatability characterized by relative standard deviation values between 2.7 % and 4.0 %, and excellent relative recovery from 85.0 to 102.0 % spiked levels 30.0-100.0 . Significant: The present method was able to extract pesticides from fruit and vegetable matrices using 1.4 mL of organic solvent. The presence of NH2-MIL-101(Cr) in packed thin film at the pipette tip without clogging and back pressure preconcentrated the insecticide with high extraction efficiency. The adsorbent also exhibited a remarkable durability, contributing to repeated use without performance degradation.

This study developed and tested polysulfone (PSF) beads with NH2-MIL-101(Cr) as a sorbent for PT-μ-SPE. Pesticides were extracted and identified using a high-performance liquid chromatography-photodiode array detector (HPLC-PDA) on real samples such as well water, tea, and honey. PSF beads/NH2-MIL-101(Cr) were synthesized and characterized using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). In addition, the kind and quantity of eluent, pH, and sample volume were studied and optimized. The response surface methodology (RSM) was used to create regression models with a central composite design (CCD). The PSF beads/NH2-MIL-101(Cr) sorbent in PT-μSPE has a linear range of 0.7 to 100.0 μg/L. The suggested technique is highly reproducible, with RSD % (intra-day) values ranging from 2.5% to 3.5%. The technique detected pesticides in water and food samples at concentrations of 33.0–100.0 μg/L, with recovery rates ranging from 80.0% to 102.0%.

Polycyclic aromatic hydrocarbons (PAHs) are persistent soil pollutants posing serious environmental and health risks due to their toxicity, carcinogenicity, and resistance to degradation. A key challenge in remediating PAH-contaminated soils is achieving efficient, low-cost, and pollution-free degradation under natural sunlight. This study reports a sustainable Fe3O4/carbon dots/silver iodide (Fe3O4/CD/AgI) nanocomposite, synthesised entirely from waste-derived precursors including industrial iron waste and wheat straw, for the sunlight-driven photocatalytic degradation of PAHs in contaminated soil. Characterisation by FTIR, XRD, SEM, and TGA confirmed the successful formation and favourable structure of the composite. Under optimal conditions (0.2 g catalyst per 4 g soil, 48 h solar exposure), complete degradation of naphthalene and while anthracene and pyrene showed removal efficiencies of approximately 65% and 71%, respectively. The composite exhibited enhanced efficiency, especially when combined with sodium persulphate, due to the synergistic contributions of magnetic recovery by Fe3O4, broad light capture by carbon dots, visible-light responsiveness of AgI, and persulphate-activated generation of reactive oxygen species (•OH, SO4•−, O2•−). This study demonstrates that a fully waste-derived, sunlight-responsive nanocomposite can effectively degrade both low- and high-molecular-weight PAHs, offering a low-cost, environmentally friendly, and scalable strategy for in-situ soil remediation.

Pristine aluminum-based metal-organic framework (MIL-53(Al)) as a sorbent shows limited affinity toward bisphenols due to the lack of hydrophobicity in its framework. To overcome this limitation, a dual-linker MIL-53(Al) with a hydrophobic carbon chain linker was synthesized for the first time and integrated into a pipette tip-micro solid-phase extraction (PT-μSPE) method for bisphenol determination. The parameters affecting the extraction process were optimized by implementing a response surface methodology (RSM) model using central composite design (CCD). Brunauer-Emmett-Teller analysis confirmed substantial increases in pore volume and pore width for the dual-linker MIL-53(Al) (0.74 cm3/g; 5.3 nm) compared with pristine MIL-53(Al) (0.17 cm3/g; 1.22 nm). This modification boosted the extraction efficiency of dual-linker MIL-53(Al) for bisphenols determination, resulting in low detection limits (0.01–0.1 μg/L), wide linearity (0.033–200.0 μg/L), high enrichment factors (up to 209), and good precision (RSD ≤ 7.0 %) in tea, disposable cups and containers, instant noodles, PET water bottles.

Metal-organic framework (MOF)are a great advanced adsorption material for solid-phase extraction due to the structure modifications with functional groups like sulfur that enhance the adsorption of heavy metals. A new sulfur-rich three-dimensional two-linker MOF (MIL-53(Fe)) was synthesized by grafting 2-mercapto-2-thiazoline sulfur and nitrogen as the second linker and then applied as an adsorbent in pipette tip micro solid-phase extraction (PT-μSPE) for the determination of Pb (II) and Cd (II) in environmental water samples. The MOFs were characterized by FTIR, XRD, TGA, BET, and SEM, which provide evidence for its framework, thermal stability, surface area, and morphology. Optimizations of extraction parameters such as pH, sample volume, volume of desorption solvent, and acidity of desorption solvent were made to improve the analytical performance. Optimizations of extraction parameters such as pH, sample volume, volume of desorption solvent, and acidity of desorption solvent were made to improve the analytical performance. In the optimal conditions, higher surface area and adsorbent capacity per adsorbent weight were obtained for the newly synthesized adsorbent containing sulfur and nitrogen when compared to MIL-53(Fe). The linearity range of the developed method was 0.2–55 μg L−1 for Pb (II) and 0.04–20 μg L−1 for Cd (II), while it displayed exceptional linearity (r2 > 0.99) and acceptable precision (RSD% ≤ 6.3). Thio-rich double-linker MIL-53 (Fe) as adsorbent in μSPE was applied for analysis spiked river, lake, groundwater, and wastewater samples with Pb (II) concentrations ranging from 5.0 to 20.0 μg L−1 and Cd (II) concentrations from 1.0 to 5.0 μg L−1, as well as standard reference materials. The results suggest that the double linker MIL-53(Fe) bearing thio-rich may offer greater adsorption capacity for Pb (II) and Cd (II) with a significantly lower detection limit compared to the original MIL-53(Fe).

Determination of low-concentration pesticides in real samples requires a simple, rapid, low-solvent-consumption, and high-efficiency extraction method before introduction into the chromatography system. In the present research, the objectives mentioned were achieved by using the developed NH2-MIL-101(Cr)/SBA-15 nanocomposite with high extraction efficiency as a sorbent in the syringe filter–solid-phase extraction (SPE) approach, which is easy to use and has low solvent consumption. In this study, for the first time, the metal–organic framework NH2-MIL-101(Cr) was combined with Santa Barbara Amorphous-15 (SBA-15) and was used as sorbent in syringe filter-SPE for extracting some pesticides from environmental water samples. To verify the successful formation of the nanocomposite, several characterization techniques including SEM, FTIR, XRD, TGA, and BET were employed. Furthermore, the variables affecting the extraction efficiency of NH2-MIL-101(Cr)/SBA-syringe - filter-SPE-HPLC, such as the sample volume, pH, volume of eluting solvent, and type of eluting solvent were optimized by utilizing a response surface methodology (RSM) based on central composite design (CCD). The results demonstrated that the NH₂-MIL-101(Cr)/SBA-15 composite exhibited superior adsorption performance and lower detection limits for the target pesticides compared to the unmodified NH₂-MIL-101(Cr). The method achieved detection limits ranging from 0.07 to 0.6 μg/L, with a linear response range of 0.25 to 800.0 μg/L. It also showed strong repeatability, with relative standard deviation (RSD) values between 2.8 % and 5.0 %, and excellent recovery rates of 90 % to 105 % at spiked concentrations from 2.0 to 40.0 μg/L.

This study presents an efficient method for the determination of chromium and lead in various edible vegetable oils by combination of extraction induced by emulsion breaking (EIEB) and dispersive liquid-liquid microextraction (DLLME) followed by flame atomic absorption spectrometry (FAAS) detection. The technique relies on the formation of a water-in-oil emulsion, achieved by introducing an extraction phase containing 20% (w/v) Triton X-100 and 1% (v/v) nitric acid. The metal ions were extracted to the aqueous phase through centrifugation of the resulting emulsion. Subsequently, the collected aqueous phase was mixed with dithizone, and the pH of solution was adjusted at 8 and 9 for Cr and Pb, respectively. Finally, DLLME was applied to concentrate the extracted metal ions, which were then quantified using FAAS. Various factors affecting the extraction efficiency of selected the metal ions were optimized using one-variable-at-a-time method. The estimated limit of quantifications were 5.0 µg/kg and 2.0 µg/kg for lead and chromium, respectively. The standard addition method was used to construct the calibration curves. The calculated relative recoveries for the spiked oil samples ranged from 94.0% to 98.0% for chromium, and from 92.0% to 96.4% for lead. The results showed that the proposed technique offers a simple and efficient analytical methods for the determination of lead and chromium in oil samples.

A simple and effective microextraction method based on protein precipitation and continuous sample drop flow microextraction (CSDF-ME) for the extraction of trimethoprim from milk, water and plasma is reported. The precipitation with zinc acetate was used to appreciably separate trimethoprim (TMP) from the complex matrix of milk samples. After protein precipitation, TMP which was present in the upper phase was extracted and preconcentrated using CSDF-ME. To this end, the pH of the upper phase was adjusted to 10.0 and filtered. Afterwards, the extracted TMPs were concentrated by pumping the aqueous solution into a conical vial containing 35.0 μL of chloroform and 7.5 μL of DMSO (as co-solvent) at a flow rate of 0.45 mL min-1. Finally, the concentrated TMPs were determined by HPLC-UV. This is the first report on the extraction and quantification of TMP from milk samples using protein precipitation coupled with CSDF-ME-HPLC-UV. Having optimized the experimental conditions, the proposed method was thoroughly validated for milk. plasma and water. The results showed that the method was linear between 10.0 and 1200.0 μg L-1. The LOD and LOQ for TMP in different matrices were 3.0–8.0 and 10.0–25.0 μg L􀀀 1, respectively. The relative recovery and the enrichment factor were 81.6–101.3% and 19.0–40.0, respectively. The relative standard deviations for intraday precision and betweenday precision at a concentration level of 200.0 μg L-1 were 3.3–6.0 and 2.6–8.3, respectively. The resulting LOQ with trueness over 81.6%, indicates the method’s applicability for TMP analysis in complicated matrices such as milk with a considerable reduction in chemicals and reagents required for the determination.

In this study, we report the synthesis and application of a novel three-component deep eutectic solvent (DES) as a promising solvent for the extraction of antibiotics from wastewater and urine. The new DES is a mixture of choline chloride, octanoic acid and ethyl benzoate at a ratio of 1 : 20 : 13, which was employed as a solvent in the extraction of several antibiotics including metronidazole, tinidazole and levofloxacin from wastewater and urine samples using continuous sample drop flow microextraction (CSDF-ME) followed by HPLC analysis. Several characterization methods including FTIR, H-NMR and C-NMR were employed to identify and confirm the formation of the synthesized DESs. The results confirmed that the new DES could be used for reliable determination of the studied antibiotics by CSDF-ME-HPLC with limits of detection in the range of 3.0–6.0 μg L−1. The calibration curves were linear between 12.0 and 780.0 μg L−1, and repeated readings with the RSD% values ranging from 1.85% to 4.95% were obtained. The relative recoveries were between 84% and 115% for the water samples spiked with 12.0–100.0 μg L−1 metronidazole and tinidazole, and 24.0–200.0 μg L−1 levofloxacin.

In this study, we evaluated the preparation and utilization of NH2-MIL-101(Al) and NH2-MIL-101(Cr) as two efficient adsorbents for the extraction of metronidazole and cephalexin in water samples using the syringe filter-SPE method. The synthesized MOF was placed inside a syringe filter to extract the target antibiotics from the water solution following their quantification by high-performance liquid chromatography (HPLC). Various characterization methods such as SEM, FTIR, XRD, TGA, and BET were used to assess and confirm the synthesis of the studied MOFs. The comparison of the adsorption capability of the synthesized MOFs revealed that NH2-MIL-101(Al) had the greatest adsorption capability. The experimental factors affecting the extraction efficiency such as sample volume and pH, and the type and volume of the adsorption solvent were thoroughly studied and optimized. Under the optimal conditions, the detection limits were calculated to be in the range of 0.5 to 10.0 μg L−1, and a linear range between 2.0 and 800 μg L−1 was obtained. Very good repeatability with RSD values ranging between 3.2% and 5.3% was achieved. The calculated relative recovery ranged from 95% to 104% at the spiked levels of 60–150.0 μg L−1.

In this study, we report the synthesis and application of a nanocomposite comprising metal–organic framework MIL-101(Cr) and graphene nanopowder (GNP) as a promising sorbent for the extraction of organophosphorus pesticides (OPPs) in juices, water, vegetables and honey samples. A syringe filter, for the first time, was used to host the synthesized nanocomposite and extract the OPPs followed by GC–MS analysis. Different characterization methods including XRD, FTIR, TGA, BET and SEM were employed to confirm the formation of studied nanocomposite. The results indicated that the GNP/MIL-101(Cr) could provide higher capacity for adsorption of OPPs and lower detection limit compared to pristine MIL-101(Cr). The detection limits were 0.005 to 15.0 µg/Kg and the linear range found between 0.05 and 400 µg/Kg. The proposed method showed very good repeatability with the RSD values ranging from 2.9% to 7.1%. The recoveries were between 84% −110% with the spiked levels of 2.0–100.0 µg/Kg.

The synthesis and utilization of a high porous nanocomposite comprising MIL-53(Al) metal–organic framework (Al-MOF) and graphene nanopowder (GNP) is reported as a fiber coating for headspace solid-phase micro-extraction (HS-SPME) of selected organophosphorus pesticides (OPPs) from apple, potato, grape juice, tomato, and river water. The adsorbed OPPs on the coated fiber were subsequently determined using GC–MS. Several parameters affecting the efficiency of extraction including time and temperature of extraction, desorption condition of extracted analytes, pH and agitation of sample solution, and salt concentration were investigated. The optimum extraction condition was achieved at 70 °C with an extraction time of 40 min, pH = 4–8, and NaCl concentration of 6.0% (w/v). The best condition of desorption were observed at 280 °C for 2.0 min under a flow of helium gas in the GC inlet. Under optimal conditions, the detection limits ranged from 0.2 to 1.5 ng g−1 and the linear ranges between 0.8 and 600 ng g−1. The proposed method showed very good repeatability with RSD values ranging from 4.5 to 7.3% (n = 5). The relative recoveries were between 88% and 109% at the spiked level of 25.0 ng g−1 for the tomato sample. The fabricated fiber exhibited good enrichment factor (62–195) at optimum condition of HS-SPME. The applied HS-SPME technique is facile, fast, and inexpensive. The thermally stable GNP/Al-MOF exhibited a high sensitivity toward OPPs. So, this nanocomposite can be considered as a sorbent for the micro-extraction of other pesticides in food.

There is always a need to develop new, fast and non-complicated microextraction methods that consume small amounts of organic solvents. In this study, a new mode of liquid phase microextraction method, termed as continuous sample drop flow-based microextraction (CSDF−ME), was developed for the enrichment and determination of cobalt in water samples. To attain the appropriate conditions for the CSDF−ME, experimental parameters such as pH, type and volume of extraction solvent, concentration of chelating agent, salting effect, sample flow rate and sample volume, needle diameter were examined. The enrichment factor was 167 for 20 mL sample solution. The calibration graph was linear in the concentration range of 5–200 μg/L with the correlation coefficient of 0.999. The limit of detection was 1.3 μg/L. The reliability of the recommended procedure was verified by analysis of real water samples (including tap, mineral and river water) and synthetic sample spiked with known amount of cobalt, and the obtained recoveries of spiked samples have demonstrated accuracy and applicability of the proposed method.

In this work, for the first time, low-density organic solvents were employed in continuous sample drop flow microextraction (CSDF-ME) by changing the design of extraction vessel. To examine the effectiveness of the modified extraction method, different organophosphorus pesticides (OPPs) were extracted using proposed method followed by detection by gas chromatography–mass spectrometry (GC–MS). In fact, unlike conventional CSDF approach, in this study, we applied halogen-free organic solvents that are lighter than water for analytes extractions. These solvents are not only less toxic but also more environmentally friendly compared to the halogenated solvents. A conical open-end vial fixed in a small container filled with double-distilled water was used as the extraction vessel. A small amount of extraction solvent was placed at the bottom of the vial and the sample solution was pumped into the extraction vessel through a needle located inside the vial using a peristaltic pump. The sample droplets were continuously passed through the extraction solvent (hexane; 13 μL) to extract the analytes. Once the extraction was completed, the extraction solvent left at the top of aqueous phase was collected and injected into the GC–MS for further analysis. Under optimized conditions, the repeatability of the proposed method was found to be in range of 3.9–5.8 % for samples with low concentration of 5.0 μg L−1. The LOD (limit of detection) and LOQ (limit of quantification) of the method were determined in the ranges of 0.02−0.30 and 0.07–1.0 μg L−1, respectively. The EF (enrichment factor) was found to be between 510 and 960 for 8.0 mL sample solutions. The proposed method allows an extraction recovery ranging between 25.5 % and 48.0 %.

A simple, precise and sensitive analytical method, which is a combination of modified ultrasound-assisted extraction (UAE), continuous sample drop flow microextraction (CSDF-ME) and GC–MS, was developed for the extraction and determination of organophosphorus pesticides in fruit and vegetable samples. In this study, for the first time, a very small amount of organic solvent was used for the UAE, almost three times less than conventional UAE. To this end, first, the raw vegetables and fruits were finely chopped and mashed. Then, 0.8 mL of acetonitrile was added and the entire mixture was sonicated for 20 min. Afterward, in order to remove acetonitrile from the mixture and to reduce the amount of organic solvent 6.0 mL of ultra-pure water was added to the mixture, and the aqueous phase was filtered out. Next, the extracted analytes were concentrated by pumping the aqueous phase across a few microliters of organic solvent (chloroform) placed inside the bottom of a conical vial at a flow rate of 0.45 mL min−1. Finally, the extracted analytes were transferred into the GC–MS for further detection. Under the optimum conditions, the relative recovery ranged from 83.0% to 108.0%. The repeatability of the method was examined at two concentration levels (60.0 and 120.0 ng g−1), and it was obtained between 4.0 and 7.6%, and 3.2 and 6.2%, respectively (n = 5). Finally, the LOD and LOQ were found to be 0.2–20.0 ng g−1, and 1.0–60.0 ng g−1, respectively.

A novel aluminum terephthalate/Fe2O3 nanocomposite was synthesized by the addition of Fe2O3 nanoparticles into a reaction solution containing aluminum terephthalate MOF. The synthesized nanocomposite was successfully used as a fiber coating material for solid-phase microextraction (SPME) of six organophosphorus compounds (OPPs) from river water, grape juice, and tea samples. The effect of different parameters on the efficiency of SPME including desorption temperature and time, extraction temperature and time, salt concentration, pH, and agitation were thoroughly studied. The OPPs were detected and determined using GC-MS. According to the findings, a wide linear range (0.15–800 μg kg−1), low limit of detection (0.04–10 μg kg−1), and high recoveries from spiked samples (87.5–112%) were achieved with low inter-day relative standard deviation (3.2–6.7%, n = 5). The MIL-53(Al)/Fe2O3 nanocomposite showed a high extraction ability towards OPPs, and hence, it can be considered a promising adsorbent for the extraction of various pesticides in complex matrices like tea and juice.

In this paper, the technique of continuous sample drop flow microextraction (CSDF-ME) is developed by the addition of a narrow-necked conical vessel. In the developed technique, an organic solvent denser than water is used for the extraction of organophosphorus pesticides (OPPs) from fruit juice and river water, followed by analysis with GC-MS. Eight milliliters of the sample solution is pumped at 0.5 mL min−1 flow rate into 12.0 μL extraction solvent (chloroform) and placed in the narrow-necked conical vessel for extraction and pre-concentration processes. Under optimal condition, the enrichment factor (EF) and linearity are found to be in the range of 102–380 and 500.0 μg L−1 with correlation coefficient greater than 0.98, respectively. The detection limit is in the range of 0.3–1.0 μg L−1 and LOQ ranged from 2.0–5.0 μg L−1. The relative standard division (RSD) of six replicate measurements for three different concentrations (i.e., 15.0, 50.0, 150.0 μg L−1) is 3.8–8.4%, 2.6–6.0%, and 2.2–4.8%, respectively. Values of RSD% of the target pesticides at 50.0 μg L−1 concentration levels are less than 6.0%.

In this paper, we present novel developments to our recently developed method so-called “continuous sample drop flow microextraction (CSDF-ME)” technique. Previously, we showed that the CSDF-ME technique offers several advantages, including stability of extraction solvent, no need for holder device, and easy to operate. The merit of current study is to make the extraction steps faster with sample required for the analysis. The key novelty of proposed method includes usage of a solvent mixture (i.e., methanol and carbon disulfide), allowing to pump aqueous samples with a higher flow rate than the former technique which led to reduce the extraction time. Results show that the technique is cable to become faster by five times with an enrichment factor of 93 for 4.0 mL of aqueous sample. The linear range and limit of detection for Pb are found to be 0.1–6.0 and 0.03 µg L−1, respectively. The relative standard deviation for determination of 1.0 µg L−1 of Pb in a sample is 2.9% (n = 5). Furthermore, the relative recoveries of the developed CSDF-ME method for Pb in tap water, mineral water, and Standard Reference Material for apple leaves (1515) are shown to be 98, 100, and 94%, respectively.

Continuous sample drop flow-based microextraction (CSDF-ME) technique was successfully used as a sample preparation method for graphite furnace atomic absorption spectrometry (GF AAS). In this technique, a few μL of organic solvent is transferred to the bottom of a conical bottom small tube. Then a few mL of aqueous solution transforms in form fine droplets while passing through the organic solvent. At this stage, cadmium - ligand hydrophobic complex is extracted into the organic solvent. After extraction, the small conical bottom tube is transferred to the GF AAS and 15 μL of extraction solvent was injected into the graphite tube by the aim of autosampler arm. Under optimum conditions, an enrichment factor of 123 was obtained for 5.0 mL of water sample. The linear range and limit of detection for cadmium were 0.02–0.5 and 0.0075 μg L− 1, respectively. The relative standard deviation for 0.05 μg L− 1 of cadmium in water was 2.8 % (n = 5). The relative recoveries of cadmium in tap water, mineral water and Standard Reference Material for leave apple (1515) are 94, 97 and 96%, respectively. The CSDF-ME combined with GF AAS is a very simple, rapid, and repeatable method which requires low volume of sample.

Continuous sample drop flow-based microextraction (CSDF-ME) is an improved version of continuous-flow microextraction (CFME) and a novel technique developed for extraction and preconcentration of benzene, toluene, ethyl benzene, m-xylene and o-xylene (BTEXs) from aqueous samples prior to gas chromatography–flame ionization detection (GC–FID). In this technique, a small amount (a few microliters) of organic solvent is transferred to the bottom of a conical bottom test tube and a few mL of aqueous solution is moved through the organic solvent at relatively slow flow rate. The aqueous solution transforms into fine droplets while passing through the organic solvent. After extraction, the enriched analyte in the extraction solvent is determined by GC–FID. The type of extraction solvent, its volume, needle diameter, and aqueous sample flow rate were investigated. The enrichment factor was 221–269 under optimum conditions and the recovery was 89–102%. The linear ranges and limits of detection for BTEXs were 2–500 and 1.4–3.1 µg L−1, respectively. The relative standard deviations for 10 µg L−1 of BTEXs in water were 1.8–6.2% (n=5). The advantages of CSDF-ME are its low cost, relatively short sample preparation time, low solvent consumption, high recovery, and high enrichment factor.

The method relies on selective complexation of As(III) with a suitable chelating agent followed by dispersive liquid–liquid microextraction (DLLME) method. Flame atomic absorption spectrometry (FAAS) equipped with microsample introduction system was utilised for determination of As(III). 1-Undecanol and acetone were used as extraction solvent and disperser solvent respectively. Some effective parameters on complex formation and extraction have been optimised. Under the optimum conditions, the enrichment factor of 108 for As(III) was obtained from 9.8 mL of water samples. The calibration graph was linear in the range of 2–15 µg L−1 with detection limits of 0.60 µg L−1 for As(III). The relative standard deviation (R.S.D.) for ten replicate measurements of 5.00 µ gL−1 of As(III) was 6.2%. Operation simplicity and high enrichment factors are the main advantages of DLLME for the determination of As(III) without necessity for hydride generation in water samples.

In this article, a new method for the determination of organophosphorus pesticides (OPPs) in tea was developed by using dispersive liquid–liquid microextraction (DLLME) and gas chromatography–flame photometric detection (GC-FPD). A mixture of acetonitrile and n-hexane was used as an extraction solvent for the extraction of OPPs from tea samples. When the extraction process was finished, the mixture of solvents was rapidly dispersed in water; target analyte was extracted to a small volume of n-hexane, using DLLME. Recovery tests were performed for concentration 5.0 μg/kg. The recovery for each target analyte was in the range between 83.3 and 117.4%. The repeatability of the proposed method, expressed as relative standard deviation, varied between 3 and 7.8% (n = 3). The detection limit of the method for tea was found ranging from 0.030 to 1 μg/kg for all the target pesticides. Compared with the conventional sample preparation method, the proposed method has the advantage of being quick and easy to operate, and has high-enrichment factors and low consumption of organic solvent.