Dispersive liquid-liquid microextraction with solidification of floating organic droplets for simultaneous extraction of pesticides, pharmaceuticals and personal care products

Determination of insecticide residues in beverages based on MIL-100(Fe) dispersive solid-phase microextraction in combination with dispersive liquid-liquid microextraction followed by HPLC-MS/MS

A novel dispersive solid-phase microextraction method based on a metal-organic framework (MIL-100(Fe)) combined with a dispersive liquid-liquid microextraction technique was proposed for the extraction and enrichment of four insecticides in beverages. The qualitative and quantitative analysis of these insecticides was conducted using HPLC-MS/MS. To optimize the extraction process, several parameters were investigated, and the main variables were optimized using CCD-based RSM. The developed method displayed a wide linear range of 1.000-1000 ng/L and R2 values >0.993 for all four calibration curves. The method demonstrated high sensitivity, with LODs and LOQs of 0.3-0.6 ng/L and 0.8-1.0 ng/L, respectively. In addition, the greenness of the proposed method was assessed using the Complex GAPI tool, and the results showed that the proposed method exhibits benefits, such as minimal usage of organic solvents and negligible matrix influence, making it a suitable method for the detection of insecticide residues in beverages.

Determination of pesticide residues in soybeans using QuEChERS followed by deep eutectic solvent-based DLLME preconcentration prior to gas chromatography-mass spectrometry analysis

A reliable and greener alternative to the usual extraction methods is reported for the determination of pesticide residues in soybeans. This novel approach combines the classical QuEChERS extraction method with a DLLME (dispersive liquid-liquid microextraction) step, utilizing a deep eutectic solvent (DES) - camphor: hexanoic acid (1:1 molar ratio) - as the microextraction solvent. This DES has never been employed in pesticide analysis by gas chromatography-mass spectrometry of complex matrices like soybeans. A Plackett-Burman screening design was employed to optimize sample preparation variables of QuEChERS (amount of sodium chloride and magnesium sulfate, and amount of PSA and C18 sorbents) and DLLME (pH of medium, amount of sodium chloride, and volume of microextraction solvent). This design allowed for a systematic evaluation of the impact of each parameter on the method's performance. The optimized method was evaluated using a certified reference material and commercial samples of soybeans. The method exhibited high accuracy and precision for most of the analytes under study, demonstrating its applicability for pesticide residue analysis in soybeans. To assess the greenness and practicality of the developed method, the Analytical Greenness (AGREE) and Blue Applicability Grade Index (BAGI) metric systems were employed, respectively. Overall, the proposed QuEChERS-DLLME method using a DES solvent is a reliable and greener alternative to conventional extraction methods for the determination of pesticide residues in soybeans. Its high performance, coupled with its environmental friendliness, makes it a promising tool for food safety analysis.

Magnetic porous carbon material derived from imine-linked covalent organic frameworks for magnetic solid phase extraction of trace chlorine-containing herbicides in soil

Here, imine-linked covalent organic frameworks coated Fe3O4 microspheres were fabricated and employed as the self-template to prepare magnetic porous carbon material. The magnetic solid phase extraction (MSPE) performance of such magnetic covalent organic frameworks derived porous carbons (CMCOFs) were studied for the first time, and the improved MSPE performance was verified. The variations of chemical and material properties in the carbonization processes were studied, and it was found that the CMCOFs carbonated at 400°C exhibited highest adsorption efficiencies for chlorine-containing herbicides due to the formation of nitrile components at this stage. The CMCOFs retained high adsorption efficiencies (above 90 %) to chlorine-containing herbicides at wide pH range (3-12) and high salt concentration. The CMCOFs-based MSPE coupled with HPLC technique was in good potential for analysis of trace chlorine-containing herbicides in soil samples. Under the optimized conditions, this approach displayed short extraction and elution time (5 and 8 min) and low limits of detection (0.35-5.5 ng/mL) for chlorine-containing herbicides. The recoveries of spiked analytes and the relative standard deviations in real soil samples were 81.86 %-110.9 % and less than 5.92 %, respectively. This study provides an efficient method for the analysis of trace chlorine-containing herbicides in complex samples, as well as give some inspiration on material modulation by controlled carbonization to achieve improved sorption performances.

Diuretics in Different Samples: Update on the Pretreatment and Analysis Techniques

Diuretics are drugs that promote the excretion of water and electrolytes in the body and produce diuretic effects. Clinically, they are often used in the treatment of edema caused by various reasons and hypertension. In sports, diuretics are banned by the World Anti-Doping Agency (WADA). Therefore, in order to monitor blood drug concentration, identify drug quality and maintain the fairness of sports competition, accurate, rapid, highly selective and sensitive detection methods are essential. This review provides a comprehensive summary of the pretreatment and detection of diuretics in various samples since 2015. Commonly used techniques to extract diuretics include liquid-liquid extraction, liquid-phase microextraction, solid-phase extraction, solid-phase microextraction, among others. Determination methods include methods based on liquid chromatography, fluorescent spectroscopy, electrochemical sensor method, capillary electrophoresis and so on. The advantages and disadvantages of various pretreatment and analytical techniques are elaborated. In addition, future development prospects of these techniques are discussed.

Development of β-cyclodextrin crosslinked citric acid encapsulated in polypropylene membrane protected-μ-solid-phase extraction device for enhancing the separation and preconcentration of endocrine disruptor compounds

Endocrine disruptor compounds (EDCs) such as plasticisers, surfactants, pharmaceutical products, personal care products and pesticides are frequently released into the environmental waters. Therefore, a sensitive and environmentally friendly method is entailed to quantify these compounds at their trace level concentrations. This study encapsulated the β-cyclodextrin crosslinked with citric acid in a polypropylene membrane protected-μ-solid phase extraction (BCD-CA μ-SPE) device for preconcentrating the EDCs (triclosan, triclocarban, 2-phenylphenol, 4-tert-octylphenols and bisphenol A) in real water samples before the analysis by high-performance liquid chromatography. FT-IR and TGA results indicated that BCD-CA was successfully synthesised with the formation of ester linkage (1078.33 cm^-1) and O-H stretching from carboxylic acid (3434.70 cm^-1) with higher thermal stability as compared with native CD with the remaining weight above 72.1% at 500 °C. Several critical parameters such as the sorbent loading, type and amount of salts, extraction time, sample volume, sample pH, type and volume of desorption solvents and desorption time were sequentially optimised and statistically validated. Under the optimum condition, the use of BCD-CA μ-SPE device had manifested good linearity (0.5-500 μg L^-1) with the determination of the coefficient range of 0.9807-0.9979. The p-values for the F-test and t-test (6.60 × 10^-8 - 1.77 × 10^-5) were lesser than 0.05 and low detection limits ranging from 0.27 to 0.84 μg L^-1 for all studied EDCs. The developed technique was also successfully applied for EDC analyses in four distinct real water samples, namely, wastewater, river water, tap water and mineral water, with good EDCs recoveries (80.2%-99.9%), low relative standard deviations (0.1%-3.8%, n = 3) with enrichment factor ranging from 9 to 82 folds. These results signified the potential of the BCD-CA μ-SPE device as an efficient, sensitive, and environmentally friendly approach for analyzing EDCs.

A descriptive and comparative analysis on the adsorption of PPCPs by molecularly imprinted polymers

Molecularly imprinted polymers (MIPs) have aroused great attention as a new material for the removal or detection of pharmaceuticals and personal care products (PPCPs). However, it is not clear about the superiority and deficiency of MIPs in the process of removing or detecting PPCPs. Herein, we evaluated the performance of MIPs in the aspects of adsorption capacity, binding affinity, adsorption rate, and compatibility to other techniques, and proposed ways to improve its performance. Without regard to the selectivity of MIPs, for the PPCPs adsorption, MIPs surprisingly did not always perform better than the conventional adsorbents (non-imprinted polymers, biochar, activated carbon and resin), indicating that MIPs should be used where selectivity is crucial, for example recovery of specific PPCPs in an environmental sample extraction process. Compared to the traditional solid-phase extraction for PPCPs detection pretreatment, the usage of MIPs as substitute extraction agents could obtain high selectivity of specific substance, due to the uniformity and effectiveness of the specific sites. A promising development in the future would be to combine other simple and rapid quantitative technologies, such as electro/photochemical sensor and catalytic degradation, to realize rapid and sensitive detection of trace PPCPs.

Deep Eutectic Solvents as Promising Green Solvents in Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Droplet: Recent Applications, Challenges and Future Perspectives

Deep eutectic solvents (DESs) have recently attracted attention as a promising green alternative to conventional hazardous solvents by virtue of their simple preparation, low cost, and biodegradability. Even though the application of DESs in analytical chemistry is still in its early stages, the number of publications on this topic is growing. Analytical procedures applying dispersive liquid-liquid microextraction based on the solidification of floating organic droplets (DLLME-SFOD) are among the more appealing approaches where DESs have been found to be applicable. Herein, we provide a summary of the articles that are concerned with the application of DESs in the DLLME-SFOD of target analytes from diverse samples to provide up-to-date knowledge in this area. In addition, the major variables influencing enrichment efficiency and the microextraction mechanism are fully investigated and explained. Finally, the challenges and future perspectives of applying DESs in DLLME-SFOD are thoroughly discussed and are critically analyzed.

Residues and dietary intake risk assessments of clomazone, fomesafen, haloxyfop-methyl and its metabolite haloxyfop in spring soybean field ecosystem

Soybean is an important oilseed crop, but weed can have a significant effect on soybean yield. Clomazone, fomesafen, and haloxyfop-methyl are high-efficacy herbicides, and the combination of these herbicides shows an ideal effect on weed control. However, the residues of these herbicides and their impacts on human health are still largely unknown. In the current study, a rapid, sensitive, and selective method using modified QuECHERS procedure combined with HPLC-MS/MS was established to detect these herbicides in soybean matrices. The limits of quantification were 0.01, 0.01 and 0.025 mg/kg for haloxyfop-methyl, haloxyfop and fomesafen, and 0.005, 0.005 and 0.0125 mg/kg for clomazone in green soybean, soybean grain, and straw, with the average recoveries ranging from 80% to 107%. The terminal residues of the target compounds were all below the corresponding limits of quantification. The dietary risk assessment showed that the risk quotient values were far below the acceptable human consumption levels.

A natural deep eutectic solvent as a novel dispersive solvent in dispersive liquid-liquid microextraction based on solidification of floating organic droplet for the determination of pesticide residues

Current trends in analytical chemistry encourage the use of innocuous solvents to develop modern methods aligned with green chemistry. In this sense, natural deep eutectic solvents (NADESs) have emerged as a novel generation of green solvents which can be employed in sample treatments as an alternative to the toxic organic solvents commonly used so far. In this work, a new extraction method employs dispersive liquid-liquid microextraction based on a solid floating organic droplet (DLLME-SFO), by using a mixture composed of a less dense than water extraction solvent, 1-dodecanol, and a novel dispersive solvent, NADES. The methodology was proposed to extract and preconcentrate some pesticide residues (fipronil, fipronil-sulfide, fipronil-sulfone, and boscalid) from environmental water and white wine samples before analysis by liquid-chromatography coupled to ultraviolet detection (HPLC-UV). Limits of quantification (LOQs) lower than 4.5 μg L^-1, recoveries above 80%, and precision, expressed as RSD, below 15% were achieved in both samples showing that the proposed method is a powerful, efficient, and green alternative for the determination of these compounds and, therefore, demonstrating a new application for NADES in sample preparation. In addition, the DLLME-SFOD-HPLC-UV method was evaluated and compared with other reported approaches using the Analytical GREEnness metric approach, which highlighted the greenness of the proposed method.

A miniaturized spray-assisted fine-droplet-formation-based liquid-phase microextraction method for the simultaneous determination of fenpiclonil, nitrofen and fenoxaprop-ethyl as pesticides in soil samples

RATIONALE

Pesticides are a group of micropollutants that persist for a long time in the environment and pose threats to life. Much effort has been devoted to developing pre-concentration methods capable of producing samples suitable for the detection of pesticides. However, better methods are still required to detect these compounds when they are present in trace concentrations in soils.

METHOD

Spray-assisted fine-droplet-formation-based liquid-phase microextraction was used to prepare soil samples containing three different pesticides, fenpiclonil, nitrofen and fenoxaprop-ethyl, for subsequent analysis by gas chromatography/mass spectrometry (GC/MS). A spraying apparatus was used for the dispersion of the extraction solvent into the sample/standard solution to improve the extraction efficiency. Optimization studies were performed to lower the detection limits of these analytes and the results obtained by the application of the newly developed system were compared with those obtained using the conventional GC/MS method.

RESULTS

A calibration curve over the range 5.0-100 μg L^-1 was obtained under the optimal conditions. The limits of detection and quantification were 1.56-1.80 μg L^-1 and 5.21-5.98 μg L^-1 , respectively. The enhancements in detection ability over the conventional method for the three tested pesticides were 188.01, 176.96 and 517.14 for fenpiclonil, nitrofen and fenoxaprop-ethyl, respectively Recovery studies performed in soil samples were satisfactory reflecting accurate applicability of the developed method.

CONCLUSIONS

The developed microextraction method is a time-saving and simple version of the traditional dispersive liquid-liquid microextraction method that also reduces the use of dispersive solvents.

Gas chromatography-mass spectrometry determination of polycyclic aromatic hydrocarbons in baby food using QuEChERS combined with low-density solvent dispersive liquid-liquid microextraction

A sensitive GC-MS method is reported for the determination of twelve polycyclic aromatic hydrocarbons (PAHs) in baby food. The sample preparation involves QuEChERS extraction combined with low-density solvent dispersive liquid-liquid microextraction (LDS-DLLME) and ultra-low temperature (-80 °C). Plackett-Burman screening design was employed to identify the main sample preparation variables that affect the extraction efficiency, such as the volume of toluene used in LDS-DLLME. The suitability of proposed method was verified by analytical selectivity, linearity in solvent and matrix-matched calibration curves and adequate recoveries (72-112%) and precision (RSD values ≤11%), under repeatability and within-laboratory reproducibility conditions. High analytical sensitivity was achieved for the monitoring of PAHs at the strict limit of 1 µg kg^-1 fixed by the European Commission for baby foods. The validated method was applied to thirty-two commercial baby food samples, and the investigated PAHs were not detected in any sample.

Monitoring Pb in Aqueous Samples by Using Low Density Solvent on Air-Assisted Dispersive Liquid-Liquid Microextraction Coupled with UV-Vis Spectrophotometry

In this study, AA-DLLME combined with UV-Vis spectrophotometry was developed for pre-concentration, microextraction and determination of lead in aqueous samples. Optimization of the independent variables was carried out according to chemometric methods in three steps. According to the screening and optimization study, 86 μL of 1-undecanol (extracting solvent), 12 times syringe pumps, pH 2.0, 0.00% of salt and 0.1% DDTP (chelating agent) were chosen as the optimum independent variables for microextraction and determination of lead. Under the optimized conditions, R = 0.9994, and linearity range was 0.01-100 µg mL^-1. LOD and LOQ were 3.4 and 11.6 ng mL^-1, respectively. The method was applied for analysis of real water samples, such as tap, mineral, river and waste water.

Bar adsorptive microextraction technique - application for the determination of pharmaceuticals in real matrices

In the present work, bar adsorptive microextraction using miniaturized devices (7.5 × 3.0 mm) coated with suitable sorbent phases, combined with microliquid desorption (100 μL) followed by high-performance liquid chromatography with diode array detection (BAμE-μLD/HPLC-DAD), is proposed for the determination of trace level of six pharmaceuticals (furosemide, mebeverine, ketoprofen, naproxen, diclofenac and mefenamic acid) in environmental water and urine matrices. By comparing ten distinct sorbent materials (five polymeric and five activated carbons), the polymer P5 proved to be the most suitable to achieve the best selectivity and efficiency. The solvent volume minimization in the liquid desorption stage demonstrated remarkable effectiveness, being more environmentally friendly, and simultaneously increased the microextraction enrichment factor two-fold. Assays performed through BAμE(P5, 0.9 mg)-μLD(100 μL)/HPLC-DAD on 25 mL of ultrapure water samples spiked at the 4.0 μg/L level yielded average recoveries ranging from 91.4% (furosemide) to 101.0% (ketoprofen) with good precision (RSD < 10.6%), under optimized experimental conditions. The analytical performance showed convenient detection limits (25.0 - 120.0 ng/L), good linear dynamic ranges (0.1 to 24.0 μg/L), appropriate determination coefficients (r ² > 0.9983), and excellent repeatability through intraday (RSD < 10.4%)) and interday (RSD < 10.0%) assays. By using the standard addition methodology, the application of the present analytical approach on environmental waters and urine samples revealed the occurrence of trace levels of some pharmaceuticals. The solvent minimization during the back-extraction step associated with the miniaturization of BAμE devices proved to be a very promising analytical technology for static microextraction analysis. Graphical abstract BAμE operating under the floating sampling technology for the determination of pharmaceuticals in aqueous media.

A sustainable on-line CapLC method for quantifying antifouling agents like irgarol-1051 and diuron in water samples: Estimation of the carbon footprint

In this work, in-tube solid phase microextraction (in-tube SPME) coupled to capillary LC (CapLC) with diode array detection has been reported, for on-line extraction and enrichment of booster biocides (irgarol-1051 and diuron) included in Water Frame Directive 2013/39/UE (WFD). The analytical performance has been successfully demonstrated. Furthermore, in the present work, the environmental friendliness of the procedure has been quantified by means of the implementation of the carbon footprint calculation of the analytical procedure and the comparison with other methodologies previously reported. Under the optimum conditions, the method presents good linearity over the range assayed, 0.05-10μg/L for irgarol-1051 and 0.7-10μg/L for diuron. The LODs were 0.015μg/L and 0.2μg/L for irgarol-1051 and diuron, respectively. Precision was also satisfactory (relative standard deviation, RSD<3.5%). The proposed methodology was applied to monitor water samples, taking into account the EQS standards for these compounds. The carbon footprint values for the proposed procedure consolidate the operational efficiency (analytical and environmental performance) of in-tube SPME-CapLC-DAD, in general, and in particular for determining irgarol-1051 and diuron in water samples.