2023-09

Journal of Food Composition and Analysis (Volume : 124)

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.

2023-02

Journal of Food Composition and Analysis (Issue : 1) (Volume : 118)

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.

2023-01

New Journal of chemistry (Issue : 6) (Volume : 47)

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.

2022-04

New Journal of chemistry (Issue : 21) (Volume : 46)

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.

2022-02

Food Chemistry (Issue : 130997) (Volume : 371)

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.

2022-01

Microchimica Acta (Issue : 1) (Volume : 189)

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.

2021-02

Journal of analytical chemistry (Issue : 2) (Volume : 76)

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.

2021-01

Journal of Food Composition and Analysis (Volume : 95)

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 %.

2021-01

Microchemical Journal (Issue : 2) (Volume : 160)

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.

2020-11

Microchimica Acta (Issue : 11) (Volume : 187)

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.

2020-02

Food Analytical Methods (Issue : 5) (Volume : 13)

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%.

2018-06

Journal of the Iranian Chemical Society (Issue : 11) (Volume : 15)

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.

2017-02

Microchemical Journal (Volume : 132)

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.

2014-06

Talanta (Volume : 129)

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.

2011-11

International Journal of Environmental Analytical Chemistry (Issue : 15) (Volume : 91)

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.

2009-04

Journal of hazardous materials (Issue : 3) (Volume : 169)

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.