Simultaneous determination of selected hormones, endocrine disruptor compounds, and pesticides in water medium at trace levels by GC-MS after dispersive liquid-liquid microextraction

Performance evaluation of ceramic membrane bioreactor: effect of operational parameters on micropollutant removal and membrane fouling

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.

Removal of selected pesticides, alkylphenols, hormones and bisphenol A from domestic wastewater by electrooxidation process

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.

Determination of eight endocrine disruptor pesticides in bovine milk at trace levels by dispersive liquid-liquid microextraction followed by GC-MS determination

Endocrine disrupting chemicals are chemicals that interfere with any aspect of the endocrine system. Several natural and synthetic chemicals, including pesticides, have been identified as endocrine disruptors, which potentially inhibit the reproductive activity of the hormonal system. The pervasive occurrence with trace level concentrations and extensive variety are the reported characteristics of these chemicals. In this study, a dispersive liquid-liquid microextraction method coupled with gas chromatography and mass spectrometry for the determination of eight potential endocrine disruptor pesticides (Lindane, Diazinon, Fenitrothion, Malathion, Aldrin, α-Endosulfan, β-Endosulfan, Methoxychlor) in bovine milk samples was developed. Several parameters that can influence the extraction efficiency were studied. Under optimized conditions, the calibration curves of all eight analytes presented coefficient of determination higher than 0.998 (range level of 2.0-1000 ng/mL). The limits of detection and quantification ranged from 0.90 to 5.00 ng/mL and 2.50 to 15.0 ng/mL, respectively.

Experimental Design of Vortex Assisted Switchable Solvent Homogeneous Liquid-Liquid Microextraction for Simultaneous Determination of Four Pesticides in Wastewater

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.

An accurate and sensitive analytical strategy for the determination of palladium in aqueous samples: slotted quartz tube flame atomic absorption spectrometry with switchable liquid-liquid microextraction after preconcentration using a Schiff base ligand

This study presents a green analytical method for palladium determination by slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS) following switchable liquid-liquid microextraction (SLLME). Efficient extraction of palladium was facilitated by complexation with a Schiff base ligand, synthesized specifically for this study. A three-stage thorough optimization procedure was carried out to boost the absorbance output of palladium. Complex formation was the first stage, and parameters evaluated included buffer solution pH and amount, concentration of ligand, and mixing period. The amount of switchable solvent and concentration and amount of sodium hydroxide and acid amount were optimized in the second stage. Optimization of sample and fuel flow rates and SQT parameters completed the third stage of optimization, and all optimum parameters were used to determine analytical performance of the method. The method had a broad linear dynamic range, and the calibration plots showed good linearity with R² values greater than 0.9991. The limits of detection and quantification of the SLLME-SQT-FAAS method were 15 and 50 μg/L, respectively. The precision of the method, expressed as percent relative standard deviation, was below 9.0% for all measurements. Spiked recovery results performed for a palladium electroplating bath solution gave poor results when quantified against aqueous calibration standards. Matrix matching was therefore used to improve recovery results which ranged between 97 and 105% for four different spike concentrations.

Simultaneous determination of iprodione, procymidone, and chlorflurenol in lake water and wastewater matrices by GC-MS after multivariate optimization of binary dispersive liquid-liquid microextraction

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.

Risk assessment of pesticides in estuaries: a review addressing the persistence of an old problem in complex environments

Estuaries, coastal lagoons and other transition ecosystems tend to become the ultimate reservoirs of pollutants transported by continental runoff, among which pesticides constitute the class of most concern. High amounts of dissolved and particulated organic matter greatly contribute to the accumulation of pesticides that eventually become trapped in sediments or find their way along food chains. Perhaps not so surprisingly, it is common to find elevated levels of pesticides in estuarine sediments decades after their embargo. Still, it remains challenging to address ecotoxicity in circumstances that invariably imply mixtures of contaminants and multiple factors affecting bioavailability. Despite advances in methods for detecting pesticides in waters, sediments and organisms, chemical data alone are insufficient to predict risk. Many researchers have been opting for ex situ bioassays that mimic the concentrations of pesticides in estuarine waters and sediments using a range of ecologically relevant model organisms, with emphasis on fish, molluscs and crustaceans. These experimental procedures unravelled novel risk factors and important insights on toxicological mechanisms, albeit with some prejudice of ecological relevance. On the other hand, in situ bioassays, translocation experiments and passive biomonitoring strive to spot causality through an intricate mesh of confounding factors and cocktails of pollutants. Seemingly, the most informative works are integrative approaches that combine different assessment strategies, multiple endpoints and advanced computational and geographical models to determine risk. State-of-art System Biology approaches combining high-content screening approaches involving "omics" and bioinformatics, can assist discovering and predicting novel Adverse Outcome Pathways that better reflect the cumulative risk of persisting and emerging pesticides among the wide range of stressors that affect estuaries.

Trace determination of nickel in water samples by slotted quartz tube-flame atomic absorption spectrometry after dispersive assisted simultaneous complexation and extraction strategy

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.

Accurate and sensitive determination of selected hormones, endocrine disruptors, and pesticides by gas chromatography-mass spectrometry after the multivariate optimization of switchable solvent liquid-phase microextraction

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.

Detection of Organophosphorus Pesticides in Wheat by Ionic Liquid-Based Dispersive Liquid-Liquid Microextraction Combined with HPLC

Food safety issues closely related to human health have always received widespread attention from the world society. As a basic food source, wheat is the fundamental support of human survival; therefore, the detection of pesticide residues in wheat is very necessary. In this work, the ultrasonic-assisted ionic liquid-dispersive liquid-liquid microextraction (DLLME) method was firstly proposed, and the extraction and analysis of three organophosphorus pesticides were carried out by combining high-performance liquid chromatography (HPLC). The extraction efficiencies of three ionic liquids with bis(trifluoromethylsulfonyl)imide (Tf₂N) anion were compared by extracting organophosphorus in wheat samples. It was found that the use of 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([OMIM][Tf₂N]) had both high enrichment efficiency and appropriate extraction recovery. Finally, the method was used for the determination of three wheat samples, and the recoveries of them were 74.8-112.5%, 71.8-104.5%, and 83.8-115.5%, respectively. The results show that the method proposed is simple, fast, and efficient, which can be applied to the extraction of organic matters in wheat samples.

Development and Validation of a Sensitive Method for Trace Nickel Determination by Slotted Quartz Tube Flame Atomic Absorption Spectrometry After Dispersive Liquid-Liquid Microextraction

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.

Simultaneous determination of estrone and selected pesticides in water medium by GC-MS after multivariate optimization of microextraction strategy

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.

A novel analytical approach for the determination of parathion methyl in water: quadrupole isotope dilution mass spectrometry-dispersive liquid–liquid microextraction using multivariate optimization

Dispersive liquid–liquid microextraction was coupled with quadruple isotope dilution mass spectrometry for the sensitive and accurate determination of parathion methyl in water.

Determination of lead at trace levels in mussel and sea water samples using vortex assisted dispersive liquid-liquid microextraction-slotted quartz tube-flame atomic absorption spectrometry

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.