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The harmful effects of endocrine disrupting chemicals (EDCs) to humans and other organisms in the environment have been well established over the years, and more studies are ongoing to classify other chemicals that have the potential to alter or disrupt the regular function of the endocrine system. In addition to toxicological studies, analytical detection systems are progressively being improved to facilitate accurate determination of EDCs in biological, environmental and food samples. Recent microextraction methods have focused on the use of green chemicals that are safe for analytical applications, and present very low or no toxicity upon disposal. Deep eutectic solvents (DESs) have emerged as one of the viable alternatives to the conventional hazardous solvents, and their unique properties make them very useful in different applications. Notably, the use of renewable sources to prepare DESs leads to highly biodegradable products that mitigate negative ecological impacts. This review presents an overview of both organic and inorganic EDCs and their ramifications on human health. It also presents the fundamental principles of liquid phase and solid phase microextraction methods, and gives a comprehensive account of the use of DESs for the determination of EDCs in various samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

This study employed simple polystyrene-coated magnetite nanoparticles (PS@MNPs)-assisted batch adsorption process for the removal of two antidepressant active ingredients (amitriptyline HCl and sertraline HCl) from hospital wastewater. Dominant parameters of the adsorption process including pH, adsorbent amount, and contact period were optimized through the univariate approach to enhance the adsorption efficiency. Upon reaching optimum adsorption conditions, equilibrium experiments were performed by spiking the adsorbates in hospital wastewater in the concentration range of 100-2000 μg/L. The concentrations of the adsorbates in the effluent were calculated using the matrix-matching calibration strategy to enhance the accuracy of quantification. A validated switchable solvent-based liquid phase microextraction (SS-LPME) method was employed to enrich the two active pharmaceutical ingredients (APIs) prior to sensitive determination with GC-MS (gas chromatography-mass spectrometry). The equilibrium data were mathematically modeled employing the Langmuir and Freundlich adsorption isotherm models. The isotherm constants were calculated, and the results showed that both the isotherm models fitted well with the experimental data. The efficient and simple batch adsorption strategy reported in this study was successfully employed to remove amitriptyline HCl and sertraline HCl from hospital wastewater at low concentrations., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

In this study, a magnetic sorbent assisted dispersive solid phase extraction (DSPE) method was used to preconcentrate lead ions from rooibos tea samples for determination by slotted quartz tube-flame atomic absorption spectrometry (SQT-FAAS). Cobalt ferrite magnetic nanoparticles (CoFe 2 O 4 MNPs) were synthesized by microwave assisted digestion. Limits of detection and quantification were calculated as 5.3 and 17.6 µg/L, respectively, in a linear dynamic range of 20-800 µg/L. The enhancement factor of the developed method was found to be 80-folds when compared to the detection limit of the regular FAAS system. The percent recoveries obtained for rooibos tea samples spiked at different concentrations were in the range of 77 - 125%, with high repeatability as indicated by low standard deviations. The findings of the study demonstrated that the CoFe 2 O 4 MNPs-based extraction method is a straightforward, fast, affordable, safe, and eco-friendly approach to qualifying/quantifying lead with high precision in the selected beverage sample., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Despite the many benefits derived from the unique features and practicality of nanoparticles, the release of their toxic by-products or products from the synthesis stage into the environment could negatively impact natural resources and organisms. The physical and chemical methods for nanoparticle synthesis involve high energy consumption and the use of hazardous chemicals, respectively, going against the principles of green chemistry. Biological methods of synthesis that rely on extracts from a broad range of natural plants, and microorganisms, such as fungi, bacteria, algae, and yeast, have emerged as viable alternatives to the physical and chemical methods. Nanoparticles synthesized through biogenic pathways are particularly useful for biological applications that have high concerns about contamination. Herein, we review the physical and chemical methods of nanoparticle synthesis and present a detailed overview of the biogenic methods used for the synthesis of different nanoparticles. The major points discussed in this study are the following: (1) the fundamentals of the physical and chemical methods of nanoparticle syntheses, (2) the use of different biological precursors (microorganisms and plant extracts) to synthesize gold, silver, selenium, iron, and other metal nanoparticles, and (3) the applications of biogenic nanoparticles in diverse fields of study, including the environment, health, material science, and analytical chemistry.

This study reports a liquid phase microextraction method based on binary extraction solvents, which were used to preconcentrate chlorbenside and fenobucarb from aqueous samples for determination by gas chromatography mass spectrometry. Parameters including the type, ratio, and volume of binary solvents, disperser solvent type and volume, and vortex period were optimized systematically to achieve high enrichment for the analytes. The optimum conditions obtained were used to validate the method, and the detection limits calculated for chlorbenside (0.71 ng/mL) and fenobucarb (0.33 ng/mL) correlated to enrichment factors of 399- and 912-folds, respectively. The optimum method was applied to lake water and wastewater samples in spike recovery experiments, and the results obtained (96-104%) verified the method as accurate and applicable to the aqueous sample matrices. Matrix matching calibration method was used to boost the accuracy of quantifying the two analytes in the wastewater sample, which presented interference effects. Assessment of the method's green profile based on penalty points confirmed the method's compliance with green analytical chemistry., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

In this work, a dispersive solid-phase extraction method based on Ni(OH) 2 nanoflowers (Ni(OH) 2 -NFs-DSPE) was developed to separate and preconcentrate copper ions from tap water samples for determination by flame atomic absorption spectrometry (FAAS). Ni(OH) 2 -NFs was synthesized using a homogeneous precipitation technique and used as sorbent for copper preconcentration. X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy were used to characterize the synthesized sorbent. All experimental variables were carefully optimized to achieve a high enhancement factor of 107.5-folds with respect to the detection sensitivity of the conventional FAAS. The proposed method's analytical parameters including LOD, LOQ, and linear range were determined as 1.33 μg/L, 4.42 μg/L, and 3.0-40 μg/L, respectively. To assess the applicability and reliability of the developed method, optimal conditions were applied to tap water samples and satisfactory percent recoveries (94-103%) were obtained for the samples spiked at 20 and 30 μg/L. This validated the accuracy and feasibility of the developed method to real samples. The developed method can be described as a simple, efficient, and rapid analytical approach for the accurate determination of trace copper ions in water samples., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

This study presents the preconcentration of diflufenican and azaconazole from domestic wastewater samples by using dispersive solid-phase extraction (dSPE) for determination by gas chromatography-mass spectrometry (GC-MS). Stearic acid-coated magnetic nanoparticles were used as adsorbents for dSPE method. In order to maximize the efficiency of the extraction process, parameters such as magnetic nanoparticle (MNP) type and amount, eluent type and volume, mixing type, and mixing period were all optimized. The linear range obtained for azaconazole and diflufenican was 7.50-500 ng/mL and 7.50-750 ng/mL, and their limits of detection/quantification (LOD/LOQ) were calculated as 1.3/4.3 ng/mL and 1.4/4.7 ng/mL, respectively. By comparing the LOD values of direct GC-MS and the developed dSPE method, azaconazole and diflufenican recorded approximately 35 and 38 folds enhancement in detection power. Recovery experiments with domestic wastewater were carried out to certify the proposed method's accuracy and applicability. By using the matrix matching calibration strategy, the good percent recovery results between 98 and 105% were obtained., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

This paper presents the removal of nine potential endocrine disruptors including pesticides, pharmaceuticals and industrial chemicals using a submerged membrane bioreactor (MBR) system. Two lab-scale submerged MBRs having ceramic membranes were operated at three different sludge retention times (SRT: 15, 45, 90 days) and two hydraulic retention times (HRT: 12, 6 h) and the effects of SRT and HRT on both micropollutant removal and membrane fouling were investigated. While the effect of SRT and HRT change was observed on the removal of atrazine, fluoxetine, penconazole, no significant change was detected for the other micropollutants studied. It was determined that physicochemical properties such as distribution coefficient (LogD) and hydrophobicity of micropollutants are also effective on the removal efficiency of micropollutants. High removal efficiencies ([Formula: see text] 97.5%) were observed for hydrophobic pollutants (logD > 3.2) except for penconazole (72.1%) and for hydrophilic pollutants (logD < 3.2) except for atrazine (42.5%). Membrane fouling was significantly affected by different operational parameters applied, with the slowest fouling occurring at 45 days of SRT and 12 h of HRT. However, micropollutant addition did not have a significant effect on membrane fouling. It has been shown that the simultaneous and effective treatment performance for micropollutants makes the membrane bioreactor system a promising wastewater treatment process., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

A sensitive, accurate and simple analytical method was developed to determine cadmium by slotted quartz tube-flame atomic absorption spectrometry after preconcentration/extraction with polystyrene coated magnetic nanoparticles based dispersive solid phase extraction. The surface of Fe 3 O 4 based magnetic nanoparticles was modified with polystyrene to yield higher selectivity and sensitivity in adsorption efficiency of cadmium. The nanoparticles were dispersed into the aqueous solution to extract/separate cadmium. Significant parameters of the method including magnetic nanoparticle amount, mixing effect, effect of ionic strength, eluent concentration and sonication period were optimized to achieve optimal conditions for the analyte. The limit of detection and quantification values of the developed method were found to be 0.62 and 2.1 ng/mL, respectively. Under the optimum conditions, enhancement of the detection power for cadmium were calculated as 102 folds for the developed method. The developed method was then applied to cigarette ash to test its accuracy and applicability. Total cadmium was found to be between 402 and 450 ng/g in the ashes of different cigarette brands commercially available in Turkey. The accuracy of quantifying cadmium in the complex ash samples was enhanced by using the matrix matching calibration strategy. The developed method provides sensitive and selective determination of cadmium at ng/mL levels even at complex cigarette ash samples. High percent recovery results (90-102%) were obtained from spiked real samples., (© 2022. The Author(s), under exclusive licence to The Japan Society for Analytical Chemistry.)

Antarctica has seen an increase in scientific research and tourism, and anthropogenic activities such as incineration of waste products and fuel combustion for energy and transportation are potential contamination sources to the ecosystem. Polycyclic aromatic hydrocarbons are common products of incomplete combustion of organic compounds and could be among accumulating contaminants in Antarctica. Thus, this study sought to develop a sensitive dispersive liquid-liquid microextraction method for the determination of 15 polycyclic aromatic hydrocarbons by gas chromatography mass spectrometry. Parameters that were relevant to the extraction method were carefully optimized and validated using aqueous standard solutions. The optimum method recorded detection limits in the range of 0.20-6.1 µg/L for the analytes. Spike recovery experiments were carried out on artificial seawater, rock-soil, and moss samples, using matrix matching calibration to mitigate effects of the sample matrices. The samples analyzed included seawater, lake, rock-soil, moss, seaweed, and feces samples all collected from the Horseshoe and Faure Islands in Antarctica. The percent recovery results obtained for the samples spiked at different concentrations ranged between 86 and 115%., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Background: Epilepsy is a neurologic condition that is occurs globally and is associated with various degrees of seizures. Levetiracetam is an approved drug that is commonly used to treat seizures in juvenile epileptic patients. Accurate quantification of the drug's active compound and determining its stability in the stomach after oral administration are important tasks that must be performed. Results & methodology: Levetiracetam was extracted from drug samples and quantified by gas chromatography mass spectrometry using calibration standards. Stability of levetiracetam was studied under various storage conditions and in simulated gastric conditions. The calibration plot determined for levetiracetam showed good linearity with a coefficient of determination value of 0.9991. The limits of detection and quantification were found to be 0.004 and 0.014 μg·ml -1 , respectively. The structural integrity of levetiracetam did not change within a 4-h period under the simulated gastric conditions, and no significant degradation was observed for the different storage temperatures tested. Discussion & conclusion: An accurate and sensitive quantitative method was developed for the determination of levetiracetam in drug samples. The stability of the drug active compound was monitored under various storage and gastric conditions. The levetiracetam content determined in the drug samples were within ±10% of the value stated on the drug labels.

This study utilized switchable solvent liquid-phase microextraction (SS-LPME) to enrich eleven nervous system active pharmaceutical ingredients (APIs) from aqueous samples for their determination at trace levels by gas chromatography mass spectrometry. The analytes selected for the study included APIs utilized in antidepressant, antipsychotic, antiepileptic, and anti-dementia drugs. Parameters of the microextraction method including switchable solvent volume, concentration and volume of the trigger agent (sodium hydroxide), and sample agitation period were optimized univariately to boost extraction efficiency. Under the optimum conditions, the detection limits calculated for the analytes were in the range of 0.20-8.0 ng/mL, and repeatability for six replicate measurements as indicated by percent relative standard deviation values were below 10%. Matrix matching calibration strategy was used to enhance quantification accuracy for the analytes. The percent recovery results calculated for the eleven analytes ranged between 86 and 117%., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

In this study, seven compounds of environmental and health concern were treated by electrooxidation to determine their removal efficiencies from domestic wastewater. A batch type lab-scale reactor was used for the treatment process, and the analytes studied included two obsolete pesticides, two alkylphenols, two hormones, and bisphenol A. Titanium oxide and graphite electrodes were used as anode and cathode, respectively. Parameters of the electrooxidation process including pH of wastewater, ionic strength, applied current and treatment period were optimized by the univariate approach to maximize the removal efficiency of the analytes from wastewater. The optimum conditions were determined as nonadjusted pH of wastewater, 1.5 A current, 15 min treatment period and 5.0 g/L sodium chloride. Dispersive liquid-liquid microextraction was used to preconcentrate analytes before and after treatment in order to calculate the removal efficiency of analytes. The removal efficiency obtained under the optimum conditions was satisfactory for all seven analytes at different influent concentrations.

This study presents a Fenton digestion method for milk samples based on UV irradiation for cadmium determination using flame atomic absorption spectrometry. The method was developed as an alternative to microwave digesters, using very basic apparatus and easy to acquire chemicals. Fenton digestion process was performed by the help of citric acid coated magnetic nanoparticles. Optimum conditions of the digestion process were applied to milk samples to evaluate analytical performance of the method. Limit of detection and limit of quantification values calculated for cadmium in milk were 0.53 and 1.8 mg/L, respectively. The method was applied to three different milk samples to validate the method's suitability and accuracy. Percent recovery values calculated for the samples spiked at two different concentrations ranged between 86 and 111%. Due to differences in the content of the spiked and control/standard milk samples, exact matrix matching calibration strategy using the same brand of milk sample in the preparation of calibration standard was employed and the accuracy of cadmium quantification was greatly enhanced (≈100%)., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Six arsenic species, namely arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AsB) and arsenocholine (AsC) were speciated using a combination of high-performance liquid chromatography and inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Under optimum chromatographic conditions, six arsenic species were well separated, and the performance of the combined system (HPLC-ICP-MS) for the species was determined. The limits of detection were calculated in the range of 0.14-0.29 ng/mL, and the corresponding quantification limits ranged between 0.45 and 0.97 ng mL -1 for the species. Spike recovery experiments performed on rice samples were used to validate the method's applicability to complex matrices. The recovery results calculated ranged between 93 and 109%, validating the method's applicability. Triplicate measurements for all spiked samples recorded percent relative standard deviation values below 10%., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background: Determination of emerging pollutants including pharmaceuticals, pesticides, industrial chemicals and hormones in different environmental samples is very important for human health., Objective: Experimental design enabled parameters to be evaluated for their effects onextraction output as well as their interactive effects., Method: A multivariate experimental design was used to attain optimum conditions of a dispersive liquid-liquid microextraction method for preconcentration of pesticides and pharmaceuticals for determination by GC-MS., Results: The optimum parameters suggested by the design model were 200 µL of chloroform, 1.96 mL of ethanol, and 40 s vortexing period. LOD and LOQ were calculated using linear calibration plots of the analytes developed in the standard concentration range of 2.0 μg/L-2.0 mg/L., Conclusions: Enhancement in detection power of the analytes recorded by the optimized method with respect to direct GC-MS determination (based on LOD values) was in the range of 3.6 and 539 folds. Spiked recovery experiments for municipal, medical, and synthetic wastewater samples yielded low recovery results when calculated against aqueous standard solutions. Matrix matched calibration standards were used to mitigate interferences from the waste samples and the percent recoveries obtained were close to 100%. This established accuracy and applicability of the developed method., Highlights: The detection limits were found between 0.50 ng/mL and 37 ng/mL. An accurate, simple and sensitive analytical method was developed for the analytes., (© AOAC INTERNATIONAL 2020. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Traditional copper coffee pots are widely used in these modern times and daily consumption of coffee brewed in overused/old pots increases the risk of copper ingestion. This study employed a green switchable solvent-based liquid-phase microextraction (SS-LPME) method to isolate and preconcentrate copper from water boiled in coffee pots. Copper was determined by a flame atomic absorption spectrometry (FAAS) system coupled with a slotted quartz tube (SQT). 1,5-Diphenylcarbazone was added to aqueous samples to form a complex with copper before the extraction step. Box-Behnken experimental design was applied to select optimum conditions of the extraction method that were used to validate the analytical method. The limits of quantification and detection of the optimized SS-LPME-SQT-FAAS method were determined as 9.1 and 2.7 μg/L, respectively. Water samples boiled in traditional coffee pots were spiked at different concentrations and analyzed to ascertain the method's accuracy and applicability to real samples. Satisfactory recovery results obtained in the range of 92-107% established good accuracy, and percent relative standard deviations lower than 8.0% also proved high precision.

This work presents a sensitive and rapid analytical method for the determination of oxcarbazepine in human plasma and urine samples. A vortex-assisted switchable hydrophilicity solvent-based liquid phase microextraction (VA-SHS-LPME) was used to preconcentrate oxcarbazepine from the samples before the determination by gas chromatography mass spectrometry. The switchable hydrophilicity solvent was synthesized by protonating N,N-dimethylbenzylamine with carbon dioxide to make it totally miscible with an equivalent volume of water. Parameters of the VA-SHS-LPME method including volume of switchable hydrophilicity solvent, concentration/volume of sodium hydroxide and vortex period were systematically optimized. Under the optimum conditions, good linearity ranging from 27.03 to 353.47 μg/kg was obtained for the analyte. Limit of detection and quantitation values were found to be 6.2 and 21 μg/kg (mass base), respectively. The relative standard deviation was calculated as 6.9% for six replicate measurements of the lowest concentration of the calibration plot. Satisfactory recovery results were calculated in the range of 97-100% for human plasma and urine samples spiked at five different concentrations., (© 2020 John Wiley & Sons, Ltd.)

Background: Pesticides are chemicals used mainly to protect plant crops in order to increase their production efficiency and quality., Objective: Switchable-solvent homogeneous liquid-liquid microextraction was optimized using a Box-Behnken experimental design and validated on a gas chromatography mass spectrometry system for the determination of analytes., Method: The significance of independent variables (switchable solvent volume, sodium hydroxide volume, and vortex period) and their interactions were evaluated by analysis of variance at 95% confidence limits (α = 0.05)., Results: The LOD and LOQ ranges of the analytes were found to be 0.42-1.90 µg/L and 1.36-6.33 µg/L, respectively. Percentage recovery results were found to be in the range of 87-113% in spiking experiments., Conclusions: A simple, efficient, and accurate analytical method was developed for the simultaneous determination of the selected pesticides. Highlights: Matrix matching was used to enhance quantification accuracy for real samples., Highlights: Matrix matching was used to enhance quantification accuracy for real samples., (© AOAC INTERNATIONAL 2020. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

A multivariate experimental design was used to attain optimum conditions of a dispersive liquid-liquid microextraction (DLLME) method for preconcentration of pesticides and pharmaceuticals for determination by gas chromatography mass spectrometry (GC-MS). Experimental design enabled parameters to be evaluated for their effects on extraction output as well as their interactive effects. The optimum parameters suggested by the design model were 200 µL of chloroform, 1.96 mL of ethanol and 40 s vortexing period. Limits of detection and quantification (LOD and LOQ) were calculated using linear calibration plots of the analytes developed in the standard concentration range of 2.0 µg/L-2.0 mg/L. Enhancement in detection power of the analytes recorded by the optimized method with respect to direct GC-MS determination (based on LOD values) was in the range of 3.6 and 539 folds. Spiked recovery experiments for municipal, medical and synthetic wastewater samples yielded low recovery results when calculated against aqueous standard solutions. Matrix matched calibration standards were used to mitigate interferences from the waste samples, and the percent recoveries obtained were close to 100%. This established accuracy and applicability of the developed method., (© AOAC INTERNATIONAL 2020. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Membrane bioreactors (MBRs) are rapidly developing systems widely used for the treatment of municipal and industrial wastewater prior to their discharge into the environment. Membrane fouling is the most important challenge in MBRs, because it negatively affects membrane performance, resulting in low permeate flux, higher transmembrane pressure and frequent membrane cleaning/replacement. In this study, the effect of tea and coffee on sludge characteristics, membrane fouling and the bacterial signalling molecule N-butyryl-l-homoserine lactone ( C4-HSL) in a membrane bioreactor system were investigated. For this purpose, four different continuously operated membrane bioreactors, treating synthetic domestic wastewater and dairy wastewater were operated in parallel under the same conditions. The results indicated that the soluble microbial products (SMP) and the extracellular polymeric substances (EPS) in the reactors showed similar trends for both synthetic domestic and dairy wastewater, where protein levels were higher than carbohydrate levels. Other parameters such as floc size, zeta potential, hydrophobicity, sludge volume index and capillary suction time were also analysed prior to and after the addition of coffee and tea. Analysis of the wastewater samples by GC-MS revealed that coffee and tea significantly enhance the extraction efficiency of C4-HSL. The results obtained in this study can serve as a good basis for further research.

A novel derivatization method for the determination of propineb by gas chromatography-mass spectrometry (GC-MS) was developed in this study. This was achieved by isothiocyanate derivatization of the analyte by potassium persulfate and potassium carbonate in water medium. Dispersive liquid-liquid microextraction (DLLME) was employed to isolate and preconcentrate the derivatized analyte into an organic phase. All method parameters including concentration/volume of potassium persulfate and potassium carbonate salts, type/period of mixing for derivatization reaction and microextraction process were systematically optimized to lower the detection limit. Under the optimum experimental conditions, the limit of detection (LOD) and limit of quantitation (LOQ) values were calculated as 0.15 mg/kg and 0.52 mg/kg, respectively. The developed method was checked for its accuracy and applicability by spiking black tea and infant formula samples, and the respective percent recovery results were found to be in the range of 99-102% and 98-103%, respectively., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this study, a switchable solvent-based liquid-phase microextraction method was developed to preconcentrate selected pesticides from tap water and wastewater matrices for determination by gas chromatography-mass spectrometry. A thorough optimization process was performed for prominent extraction parameters such as switchable solvent amount, concentration/amount of sodium hydroxide, salt type and mixing period. Optimum parameters obtained at the end of the optimization process were applied to aqueous standard solutions to validate the method. The linear dynamic ranges of all four analytes were appreciably wide with coefficient of determination values greater than 0.9997. The limits of detection and quantification (LOD and LOQ) were calculated for the analytes in the ranges of 0.38-2.0 ng/mL and 1.3-6.5 ng/mL, respectively. Spiked recovery experiments were used to validate the accuracy of the developed method and to determine the performance of the method in different sample matrices. Tap water, municipal wastewater and medical wastewater were spiked at three different concentrations and analyzed under the method's optimum conditions. The percent recovery results calculated for the samples were in the range of 79-107%, and this validated the method's accuracy and applicability to complex matrices such as municipal and medical wastewater samples.

An accurate and sensitive dispersive liquid-liquid microextraction method based on binary solvents was used to enrich prothiofos, oxadiargyl, and gamma-cyhalothrin for quantification by GC-MS. The combination of two extraction solvents (binary mixture) resulted in higher extraction efficiencies compared to the single solvent extraction systems. Parameters of the binary extraction method where optimized to enhance the extraction output of the analytes. The limits of detection calculated for the analytes ranged between 0.59 and 1.6 ng/mL. Linear calibration plots of the analytes covered wide concentration ranges with R 2 values greater than 0.9996 and percent relative standard deviation lower than 10%. Spiked recovery experiments were performed well and wastewater at two different concentrations and satisfactory results (89-104%) were obtained. The binary solvent microextraction method was combined with QuEChERS to quantify the analytes in pineapple matrix, using matrix matching method to enhance the accuracy of the method to almost 100%.

This study describes the development of a sensitive and accurate dispersive liquid-liquid microextraction strategy for the preconcentration and determination of selected pesticides in wastewater and lake water samples by gas chromatography-mass spectrometry. Determination of these pesticides at high accuracy and precision is important because they can be still be found in environmental samples. The type of extraction solvent and type of disperser solvent were optimized using the univariate approach. Furthermore, a Box-Behnken experimental design was used to set up a working model made up of 18 combinations of three variables, tested at three levels. The parameters fitted into the design model were volume of extraction solvent, disperser solvent volume, and mixing period. Analysis of variance was used to evaluate the experimental data to determine the significance of extraction variables and their interactions, before selecting optimum extraction conditions. The method was then applied to aqueous standard solutions between 2.0 and 500 μg L -1 , and the limit of detection (LOD) and quantification (LOQ) values obtained for the analytes were between 0.37-2.8 and 1.2-9.4 μg L -1 , respectively. The percent recoveries were calculated in the range of 92-114 and 96-110% for wastewater and lake water, respectively. These results validated the accuracy and applicability of the method to the selected matrices.

QuEChERS and switchable solvent liquid phase microextraction (SS-LPME) were respectively used as pretreatment and preconcentration tools to allow trace determination of selected organochlorine pesticides and hormones by gas chromatography mass spectrometry (GC-MS). The effects of principal SS-LPME variables and their interactions were evaluated with a Box-Behnken experimental design. The limits of detection obtained by direct GC-MS determination were enhanced by about 33-115 folds under the optimized SS-LPME conditions. The SS-LPME method was applied to tap water, well water, lake water, medical wastewater and tea samples. Satisfactory recovery results were obtained for all but the tea samples using the conventional calibration plot. Matrix matched calibration standards were used to improve the percent recovery of analytes to almost 100% in the tea samples. The combined QuEChERS and SS-LPME method was applied to tomato samples and matrix matching was also used to significantly improve analyte recoveries., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

This study describes the determination of lead at trace levels by slotted quartz tube flame atomic absorption spectrophotometry (SQT-FAAS) after preconcentration by the help of stearic acid coated magnetic nanoparticle (SAC-MNPs) based sonication assisted dispersive solid phase extraction (SA-DSPE). SAC-MNPs were used due to their easy separation advantages by the application of external magnetic field. All extraction parameters were optimized by response surface methodology based experimental design. The experimented data was evaluated by the analysis of variance. Under the optimum conditions, about 31 folds enhancement in detection power was obtained over the conventional FAAS. The recovery results obtained for samples spiked at 60 and 120 ng mL -1 were 106.6 and 102.6%, respectively, validating the method as accurate and applicable to the red pepper matrix. The percent relative standard deviations of the results were under 5.0% even at low concentrations that established high precision for replicate extractions and instrumental readings., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

This study presents the use of Quick Easy Cheap Efficient Rugged and Safe (QuEChERS) as an effective sample cleaning procedure and switchable solvent liquid phase microextraction (SS-LPME) as a preconcentration tool for the determination of fenazaquin by gas chromatography mass spectrometry (GC-MS) at ultratrace levels. After a thorough optimization process, 0.50 mL of switchable solvent, 1.5 mL of 1.0 M sodium hydroxide, and 15 s of vortexing were determined as optimum conditions of the SS-LPME method. The limit of detection (LOD) and limit of quantitation (LOQ) determined using the optimum method (SS-LPME/GC-MS) were 0.05 and 0.18 ng/mL, respectively. Compared with direct GC-MS determination of fenazaquin, the optimum method yielded about 800-fold enhancement in detection power of GC-MS. The method was applied to lake, irrigation canal, well, and wastewater samples. In order to test the method's applicability on fresh tomato samples, a QuEChERS method was used before applying the SS-LPME method. Matrix-matched calibration standards were used to enhance the accuracy of fenazaquin quantification in spiked tomato samples to obtain recovery results close to 100%.

In this study, a binary mixture in dispersive liquid-liquid microextraction was used for the preconcentration and determination of selected pesticides, pharmaceutical and hormone by GC-MS. A Box-Behnken experimental design was used to optimize the amounts of binary mixture, dispersive solvent and salt. The optimum parameters obtained were dichloromethane/1,2-dichloroethane binary mixture (200 µL), ethanol (2.0 mL) and potassium nitrate (1.0 g). Analytical performance of each analyte was determined under the optimum conditions and the lowest and highest detection limits calculated were 0.43 and 5.9 ng/mL. Low relative standard deviations were obtained even in the lowest concentrations in linear calibration plots, signifying high precision for the sample preparation procedure and instrumental measurement. Accuracy of the developed method and applicability to real samples was tested on well, lake, hospital and municipal wastewater. The percent recoveries acquired at different spiked concentrations were satisfactory (89%-108%), validating the accuracy of the method for the quantification of the analytes in the selected matrices.

Nanosized magnetic nanoparticles (MNPs) were utilized for the preconcentration of 12 analytes including pesticides, alkylphenols, hormones and bisphenol A prior to their determination by GC-MS. The extraction efficiency of the MNPs was enhanced by coating them with oleic acid and stearic acid. A binary system consisting of the two kinds of coated MNPs was optimized using a multivariate experimental design which evaluated main experimental variables and their interactions. Under optimized conditions, the following figures of merit are found: (a) Enrichment factors ranging from 64 to 345; (b) detection limits between 0.13 and 2.7 μg L -1 ; and (c) recoveries from spiked underground well water and municipal wastewater between 90 and 109%. The closeness of the results to 100% validated the method and underpinned its trueness for quantitative determinations. Graphical abstract Schematic representation of sonication-assisted binary micro-solid phase extraction based on oleic acid coated (OAc-) and stearic acid coated (SAc-) magnetite nanoparticles (MNPs) for the determination of endocrine disrupting compounds by GC-MS (TIC: total ion chromatogram).

This study presents an accurate method for the determination of alkyl phenols and bisphenol A at trace levels using gas chromatography mass spectrometry after preconcentration with switchable liquid-liquid microextraction. In order to achieve high extraction output, the environmentally friendly switchable liquid-liquid microextraction method was optimized by varying parameters such as amount of switchable solvent, sodium hydroxide concentration/amount and the mixing period in a Box-Behnken experimental design. Under optimum extraction conditions, the limits of detection calculated for the analytes were between 0.13 and 0.54 ng/mL. The analytes showed good linearity over broad calibration ranges, and low percent relative standard deviations established good precision. Spiked recovery studies were performed on municipal wastewater and tap water to determine the method's suitability and accuracy, and the results (87-106%) obtained were satisfactory. Bisphenol A was detected (4.0-14 ng/mL) in four plastic samples investigated under high temperature conditions., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Presented in this study is a simple but efficient switchable polarity solvent microextraction strategy for etrimfos preconcentration from water and food samples for quantification by gas chromatography mass spectrometry. Repeatability of the extraction process and instrumental measurements were enhanced by using deuterated bisphenol A as internal standard. Significant parameters of the extraction method were fitted into an experimental design model to study the effects of parameters on extraction output, as well as mutual effects of combined parameters. The design model was formed with 51 experimented data obtained from the combination of sodium hydroxide volume, switchable solvent volume, and vortex period at three levels. The method was validated by applying optimum conditions attained from the model predictor. The detection limit was found to be 1.3 ng/mL and it corresponded to an enhancement factor of about 54 folds when compared to direct GC-MS measurement. Etrimfos was not detected in the water and food samples tested but the results (92-107%) obtained from spiked recovery experiments established that etrimfos when present in the selected matrices can be accurately and precisely quantified.

In this study, the detection power of a gas chromatography mass spectrometer (GC-MS) for procymidone and chlorflurenol was significantly enhanced using switchable solvent liquid phase microextraction (SS-LPME) as a preconcentration tool. This was achieved by a comprehensive optimization of significant parameters to the SS-LPME method such as switchable solvent amount, concentration and amount of sodium hydroxide, pH effect and mixing effect. The optimum experimental conditions obtained were used to determine analytical figures of merit for the analytes. The limits of detection obtained were 0.44 and 2.9 ng/mL for procymidone and chlorflurenol, respectively. The optimum method was applied to water sampled from an irrigation canal and two wastewater samples. The samples were spiked at two concentrations and the percent recovery results obtained ranged between 86 and 115% for both analytes. The recovery results together with the low standard deviations recorded validated the method as accurate and precise.

This study reports the optimization of a binary dispersive liquid-liquid microextraction method for the determination of iprodione, procymidone, and chlorflurenol by gas chromatography mass spectrometry. The study was aimed at using two extraction solvents to increase the extraction efficiency of all analytes. The binary solvents recorded results higher than the mono-solvents. After examining the effects of main experimental parameters and their interactions by analysis of variance, 200 μL of binary mixture (dichloromethane and 1,2-dichloroethane), 2.5 mL of ethanol, and 15 s vortex were obtained as optimum parameters. The detection and quantification limits calculated for the analytes were found to be between 0.30-1.6 and 1.0-5.3 ng/mL, respectively. Enhancement in detection power calculated as a ratio of the binary extraction detection limit to the detection limit of direct GC-MS analysis was 105-, 214-, and 233-fold for chlorflurenol, iprodione, and procymidone, respectively. In order to check the accuracy of the developed method, recovery study was performed. Water sampled from a lake and two wastewater samples from treatment facilities were spiked at two concentrations, and the percent recovery calculated for the samples ranged between 87 and 116%. These results confirmed the suitability of the method to real samples for accurate determination of the analytes at trace levels.

This study presents a new method for the determination of nickel in aqueous samples by slotted quartz tube-flame atomic absorption spectrometry (SQT-FAAS) after a dispersive assisted simultaneous complexation and extraction (DASCE) process. Synthesized ligand was directly dissolved in the extraction solvent to eliminate the complex formation step prior to the extraction. All parameters of the SQT-FAAS and DASCE method were systematically optimized to improve the detection power of nickel for trace determinations. Under the optimum experimental conditions, the optimized method (DASCE-SQT-FAAS) recorded 137-fold enhancement in detection power over the conventional FAAS. The limits of detection and quantification were determined to be 1.6 μg/L and 5.2 μg/L, respectively. The calibration plot was linear over a wide concentration range and the precision for replicate measurements was appreciably high. Nickel was not detected in five different water samples but spiked recovery tests for three samples yielded results that were close to 100%, confirming the method's accuracy and applicability to the matrices tested.

Switchable solvent liquid-phase microextraction was combined with gas chromatography and mass spectrometry to improve the sensitivity and accuracy for the determination of selected endocrine disruptors, pesticides, and hormones. The extraction method was used to complement gas chromatography with mass spectrometry by preconcentrating analytes for trace determinations. A Box-Behnken experimental design was used to evaluate the main variables and their interaction effects, and optimum parameters were selected based on the model of experimented results. Application of optimum extraction conditions to mixed standard solutions yielded limits of detection and quantitation values between 0.20-13 and 0.90-46 ng/mL, respectively. The accuracy and the applicability of the developed method was checked in tap water and two different wastewater samples by spiked recovery tests. The percent recoveries recorded for the analytes were between 91 and 110%, and percent relative standard deviation values were all below 10%. The results indicate that the method can be used for the accurate and sensitive determination of these analytes in the presented matrixes., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This study describes the determination of trace levels of copper by slotted quartz tube atomic absorption spectrometry after dispersive liquid-liquid microextraction. A ligand synthesized from the reaction of salicylaldehyde and 1-naphthylamine was used to form coordinate copper complex prior to extraction. All parameters that influence the output of complex formation, extraction, and instrumental measurement were optimized to enhance the absorbance signal of copper. Under the optimum conditions, about 104-fold enhancement in sensitivity was recorded over the conventional flame atomic absorption spectrometer, corresponding to a 0.51 ng/mL detection limit. The percent relative standard deviation calculated for the lowest concentration (4.8%) indicated high precision for the experimental procedure. Accuracy and applicability of the optimum method were determined by performing spiked recovery tests on urine, lake water, and mineral water samples. Satisfactory recovery results were obtained between 82.2 and 106.3% at four different concentrations. Matrix matching method was also performed to increase the accuracy of quantification, and the percent recovery calculated for 175 ng/mL was 105.14%.

In this study, a switchable solvent was used to preconcentrate trace amounts of Cd from aqueous solution for its determination by flame atomic absorption spectrometry (FAAS). Protonation of N,N-dimethylbenzylamine by dry ice (solid CO 2 ) made it water soluble, and addition of sodium hydroxide converted it back to its original nonionic state for phase separation and subsequent extraction of Cd. A slotted quartz tube (SQT) was attached to the flame burner head to increase the residence time of Cd atoms in the light path. Under the optimum conditions, limits of detection and quantification were determined as 0.7 and 2.6 μg L -1 , respectively. Low relative standard deviations calculated from seven replicate measurements of the lowest concentration indicated high precision. Accuracy of the developed method was checked by using a standard reference material (SRM 1633c). Spiked recovery tests were also performed on lake water and wastewater samples at different concentrations to check the applicability of the developed method, and the results obtained (90-103%) established high recovery.

A dispersive liquid-liquid microextraction (DLLME) technique based on a solidification-of-floating-organic-drop (SFOD) procedure was developed for the determination of trace amounts of cadmium (Cd) by using a flame atomic absorption spectrometer (FAAS) fitted with a slotted quartz tube (SQT). The extraction of Cd was achieved by forming a complex with diphenylcarbazone. Parameters affecting the formation of complex and extraction outputs were carefully optimized to obtain high-absorbance signals to achieve lower LODs. An SQT was fitted on top of the flame burner head to further enhance the absorbance of the signals recorded by the FAAS. Coupling the DLLME-SFOD procedure with SQT-FAAS produced an enhancement factor of about 183. The LOD of the method was 0.23 µg/L with an RSD of 3.8%. Matrix-matching was used to overcome any low recovery results obtained with tap water and municipal wastewater.

In this study, dispersive liquid-liquid microextraction was systematically optimized for the preconcentration of nickel after forming a complex with diphenylcarbazone. The measurement output of the flame atomic absorption spectrometer was further enhanced by fitting a custom-cut slotted quartz tube to the flame burner head. The extraction method increased the amount of nickel reaching the flame and the slotted quartz tube increased the residence time of nickel atoms in the flame to record higher absorbance. Two methods combined to give about 90 fold enhancement in sensitivity over the conventional flame atomic absorption spectrometry. The optimized method was applicable over a wide linear concentration range, and it gave a detection limit of 2.1 µg L -1 . Low relative standard deviations at the lowest concentration in the linear calibration plot indicated high precision for both extraction process and instrumental measurements. A coal fly ash standard reference material (SRM 1633c) was used to determine the accuracy of the method, and experimented results were compatible with the certified value. Spiked recovery tests were also used to validate the applicability of the method.

A sensitive and accurate analytical method based on dispersive liquid-liquid microextraction was developed for the simultaneous determination of selected pesticides, hormones, and endocrine disruptors by GC-MS. The optimum conditions of the extraction procedure were determined using an experimental design of factors significantly affecting the extraction output. Analysis of variance (ANOVA) was used to evaluate the main effects of experimental factors and their interactions. The limit of detection values determined for the analytes under optimum experimental conditions were found to be between 0.30-2.0 ng/mL. The linear calibration plot of analytes span across a wide concentration range and low %RSD values from replicate measurements indicated good precision of the developed method. Spiked recovery tests were also performed on municipal wastewater, well water, lake water, sea water, and tap water matrices to determine the method's accuracy and applicability to water samples. The recovery results obtained were satisfactory for all water samples.

Dispersive liquid-liquid microextraction was coupled with quadruple isotope dilution mass spectrometry for the sensitive and accurate determination of parathion methyl in water. The two methods were complementary to each other, with DLLME preconcentrating the analyte for trace determination, and ID 4 MS maintaining the integrity of the method's accuracy and precision. An experimental design was used to optimize the extraction process. The results from the design were evaluated with the analysis of variance to determine the statistical significance of the main factors of extraction and interaction effects of these factors. A three-point calibration blend and sample blend were prepared gravimetrically by spiking with isotopically labelled parathion methyl. All four blends were left to equilibrate for three hours, after which they were preconcentrated under the optimum extraction conditions. The percent recovery recorded by this method was 99.9%, and the percent relative standard deviation was 0.32%. These results validated the accuracy and precision of the combined method.

In this study, dispersive liquid-liquid microextraction (DLLME) and slotted quartz tube (SQT) were coupled to flame atomic absorption spectrometry (FAAS) to increase the sensitivity of lead. Conditions such as the formation of the lead-dithizone complex, efficiency of the DLLME method and the output of the SQT were systematically optimized to improve the detection limit for the analyte. The conventional FAAS system was improved upon by about 3.0 times with SQT-FAAS, 32 times with DLLME-FAAS and 142 times with DLLME-SQT-FAAS. The method was applicable over a wide linear range (10-500 μg L -1 ). The limit of detection (LOD) determined by DLLME-SQT-FAAS for seawater and mussel were 2.7 μg L -1 and 270 μg kg -1 , respectively. The percent recoveries obtained for mussel and seawater samples (spiked at 20 and 50 μg L -1 ) were 95-96% and 98-110%, respectively., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A new analytical method based on dispersive liquid-liquid microextraction with gas chromatography mass spectrometry has been optimized for the simultaneous determination of paclobutrazol and triflumizole in tap water and wastewater samples. A two-level, full-factorial design that allowed the study of main effects and factor interactions was applied to analyze the influence on microextraction process by chloroform, ethanol, potassium iodide and hand shaking period. The extraction conditions selected were 200 μL of chloroform, 3.0 mL of ethanol, 2.0 g of potassium iodide and 15 s of hand shaking. The limits of detection obtained for triflumizole and paclobutrazol under optimum conditions were 0.97 and 0.29 ng/mL, respectively. Calibration plots of both analytes were linear over a wide concentration range, and good precision was observed for replicate measurements. Applicability and accuracy of the method were determined by performing spiked recovery tests. Appreciable recovery results were obtained for municipal wastewater and matrix matching was used to obtain close to 100% recovery for tap water., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Polycyclic aromatic hydrocarbons are known for their carcinogenic and mutagenic effects on human health. This therefore calls for the regulation of their concentrations in air, water, and soil. Naphthalene as the simplest in structure of the polycyclic aromatic hydrocarbons is mainly used as a starter material for other chemicals but also has impacts on human health. A method is therefore proposed for the determination of naphthalene in water samples by gas chromatography mass spectrometry after liquid-liquid extraction. The extraction method was optimized to improve the extraction output, thereby lowering the limit of detection. The limits of detection and quantification obtained for naphthalene were 4.4 and 14.6 ng mL -1 , respectively. Deuterated anthracene was used as internal standard to enhance the precision of the method, for which a relative standard deviation of 4.3% was obtained. The percent recovery of naphthalene obtained from tap water was ranged between 93.8 and 102.2.

In this study, solidified floating organic drop microextraction (SFODME) by 1-undecanol was combined with slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS) for the determination of cadmium at trace levels. Formation of a complex with 4,4'-dimethyl-2,2'-bipyridine facilitated the extraction of cadmium from aqueous solutions. Several chemical variables were optimized in order to obtain high extraction outputs. Parameters such as concentration of the ligand, pH, and amount of buffer solution were optimized to enhance the formation of cadmium complex. The SFODME method was assisted by dispersion of extractor solvent into aqueous solutions using 2-propanol. Under the optimum extraction and instrumental conditions, the limit of detection and limit of quantitation values obtained for cadmium using the combined methods (SFODME-SQT-FAAS) were found to be 0.4 and 1.3 μg L -1 , respectively. Matrix effects on the method were also examined for tap water and wastewater, and spiked recovery results were found to be very satisfactory. Graphical Abstract SFODME-SQT-FAAS system for sensitive determination of cadmium.

The need to enhance food safety has led to major advancements in pesticide productions, and though many benefits have been gained, environmental contamination has also risen from these chemicals that tend to persist in the environment. Some pesticides, together with other chemicals commonly called endocrine disruptor compounds, block the receptor sites of hormones or mimic displaced hormones, leading to imbalanced hormonal levels that result in health disorders and diseases. These chemicals occur at trace levels and are not directly detected by conventional analytical methods. A dispersive liquid-liquid microextraction method was therefore developed for preconcentration of 12 analytes including hormones, endocrine disruptor compounds, and pesticides, to be analyzed by gas chromatography mass spectrometry. This was achieved by optimizing parameters such as extractor solvent type and amount, dispersive solvent type and amount, pH, and salt effect that affect extraction output. The limits of detection and quantification of the developed method were between 0.09 and 3.36 and 0.31 and 11.19 ng mL -1 , respectively. The calibration plots of the analytes also showed good linearity and low percent relative standard deviations. Recovery studies were performed for tap water and wastewater samples, and the percent recoveries recorded were between 84 and 109%.