Fabric phase sorptive extraction followed by HPLC-PDA detection for the monitoring of pirimicarb and fenitrothion pesticide residues

Advancing micro-electrometric techniques for the detection of organophosphate and carbamate residues using cricket cholinesterase

The widespread use of organophosphate (OP) and carbamate (CM) pesticides requires efficient and cost-effective detection methods. This study introduces a micro-electrometric method using cricket cholinesterase (ChE) to detect OP and CM residues, providing a rapid and economical alternative to conventional chromatographic techniques. The parameters of the method, including the substrate concentration, incubation temperature, and incubation time, were optimized. By leveraging the sensitivity of cricket ChE to OP and CM inhibition, this approach translates enzyme inhibition into an electrical signal to quantify pesticide levels, achieving an impressive limit of detection (LOD) from 0.036 to 0.086 parts per million (ppm). This method demonstrated reproducibility and stability, making it suitable for field applications and on-site testing across various environmental matrices. This research represents a significant advancement in pesticide residue analysis with potential applications in the development of portable biosensor devices for real-time environmental monitoring and public health protection.

A facile fabric phase sorptive extraction method for monitoring chloramphenicol residues in milk samples

Determination of pharmaceutical active molecules in the biological matrices is crucial in various fields of clinical and pharmaceutical chemistry, e.g., in pharmacokinetic studies, developing new drugs, or therapeutic drug monitoring. Chloramphenicol (CP) is used for treating bacterial infections, and it's one of the first antibiotics synthetically manufactured on a large scale. Fabric phase sorptive extraction (FPSE) was used to determine Chloramphenicol antibiotic residues in milk samples by means of validated HPLC-DAD instrumentation. Cellulose fabric phases modified with polyethylene glycol-block-polypropylene glycol-block-polyethylene glycol triblock copolymer was synthesized using sol-gel synthesis approach (Sol-gel PEG-PPG-PEG) and used for batch-type fabric phase extractions. Experimental variables of the FPSE method for antibiotic molecules were investigated and optimized systematically. The HPLC analysis of chloramphenicol was performed using a C18 column, isocratic elution of trifluoroacetic acid (0.1%), methanol, and acetonitrile (17:53:30) with a flow rate of 1.0 mL/min. The linear range for the proposed method for chloramphenicol (r2 > 0.9982) was obtained in the range of 25.0-1000.0 ng/mL. The limit of detections (LOD) is 8.3 ng/mL, while RSDs% are below 4.1%. Finally, the developed method based on FPSE-HPLC-DAD was applied to milk samples to quantitatively determine antibiotic residues.

Dual sorbent coating based magnet-integrated fabric phase sorptive extraction as a front-end to gas chromatography-mass spectrometry for multi-class pesticide determination in water samples

Magnet-integrated fabric phase sorptive extraction (MI-FPSE) is a sample preparation technique that has proved to be a powerful tool for environmental analysis. The fabrication and application of magnet-integrated dual sorbent-based FPSE membrane prepared by combining two different sol-gel sorbent-coated disks of different polarities together with a magnetic bar inserted between the two membranes to allow the stirring, was examined as novel preparation technique that not required samples pretreatments. The dual sorbent-based sample preparation platforms (made up of poly(tetrahydrofuran) and Carbowax 20M) were used for the extraction of seven classes of pesticides from ambient surface water samples prior to their determination by gas chromatography-mass spectrometry. Initially, different single and dual sol-gel sorbent-based MI-FPSE membranes were evaluated in terms of their extraction efficiency. The MI-FPSE with dual sol-gel sorbents were found to be superior to the single-materials MI-FPSE devices in terms of extraction recovery. The main parameters affecting the MI-FPSE extraction protocol (e.g., adsorption time, sample volume, stirring rate, salt addition, eluent type, desorption time and elution volume) were investigated. The selected extraction protocol enabled detection limits in the range between 0.001 and 0.16 ng mL-1. Furthermore, good relative standard deviation values for the intra-day and inter-day repeatability studies were obtained and were lower than 5.9 and 9.9 %, respectively. The proposed method was successfully used for the multi-class analysis of environmental surface water samples.

Ultrasensitive Fluorescence Platform Based on AgNPs In Situ-Incorporated Zr-MOFs for the Detection of Organophosphorus Pesticides

Organophosphorus pesticides (OPPs) are extensively used in agricultural production, and the contamination caused by their residues has raised significant concerns regarding potential threats to human health. Herein, a novel fluorescence nanoprobe based on an enzyme-mediated silver nanoparticle-modified metal organic framework (AgNPs@PCN-224) was successfully prepared for the rapid detection of OPPs. Initially, AgNPs@PCN-224 were synthesized by reducing silver nitrate (AgNO3) using sodium borohydride (NaBH4) embedded into luminescent PCN-224. This triggered the inner filter effect, leading to fluorescence quenching. Meanwhile, under the catalysis of acetylcholinesterase (AChE) and choline oxidase (CHO), acetylcholine (ATCh) was decomposed to hydrogen peroxide (H2O2), which could destroy AgNPs to form Ag+ released from PCN-224 for fluorescence recovery. Instead, fenitrothion, an OPP, inhibited AChE activity, allowing the quenched fluorescence to be reactivated. Under the current optimum conditions, the fluorescence intensity had a good correlation (Y = -728.5370X + 2178.4248, R2 = 0.9869) over a dynamic range of fenitrothion concentrations from 0.1 to 500 ng/mL, with an LOD of 0.037 ng/mL. In addition, the anti-interference ability and robustness of the proposed sensor was verified for the monitoring of fenitrothion in tea with recoveries of 87.67-103.72% and the relative standard deviations (RSD) < 5.43%, indicating that the system has excellent prospects for OPP determination in practical applications. Furthermore, this work provides a universal platform for screening other enzyme inhibitors to detect OPPs.

PEDOT: PSS/AuNPs-Based Composite as Voltammetric Sensor for the Detection of Pirimicarb

An electrochemical sensor for the pesticide Pirimicarb (PMC) has been developed. A screen-printed electrode (SPCE) was used and modified with the conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) and gold nanoparticles (AuNPs) to enhance electrochemical proprieties. Electrode characterizations were performed using scattering electron microscopy (SEM) and cyclic voltammetry (CV). With the SPCE/PEDOT:PSS/AuNPs modified electrode, a new peak at 1.0 V appeared in the presence of PMC related to the PMC oxidation. To elucidate the mechanism of PMC oxidation, Gas Chromatography-Mass Spectrometry (GC-MS), where two major peaks were identified, evidencing that the device can both detect and degrade PMC by an electro-oxidation process. Exploring this peak signal, it was possible the sensor development, performing detection from 93.81-750 µmol L^-1, limits of quantification (LOQ) and detection (LOD) of 93.91 µmol L^-1 and 28.34 µmol L^-1, respectively. Thus, it was possible to study and optimization of PMC degradation, moreover, to perform detection at low concentrations and with good selectivity against different interferents using a low-cost printed electrode based on graphite modified with conductive polymer and AuNPs.

Rapid Determination of Non-Steroidal Anti-Inflammatory Drugs in Urine Samples after In-Matrix Derivatization and Fabric Phase Sorptive Extraction-Gas Chromatography-Mass Spectrometry Analysis

Fabric phase sorptive extraction (FPSE) has become a popular sorptive-based microextraction technique for the rapid analysis of a wide variety of analytes in complex matrices. The present study describes a simple and green analytical protocol based on in-matrix methyl chloroformate (MCF) derivatization of non-steroidal anti-inflammatory (NSAID) drugs in urine samples followed by FPSE and gas chromatography-mass spectrometry (GC-MS) analysis. Use of MCF as derivatizing reagent saves substantial amounts of time, reagent and energy, and can be directly performed in aqueous samples without any sample pre-treatment. The derivatized analytes were extracted using sol−gel Carbowax 20M coated FPSE membrane and eluted in 0.5 mL of MeOH for GC-MS analysis. A chemometric design of experiment-based approach was utilized comprising a Placket−Burman design (PBD) and central composite design (CCD) for screening and optimization of significant variables of derivatization and FPSE protocol, respectively. Under optimized conditions, the proposed FPSE-GC-MS method exhibited good linearity in the range of 0.1−10 µg mL−1 with coefficients of determination (R2) in the range of 0.998−0.999. The intra-day and inter-day precisions for the proposed method were lower than <7% and <10%, respectively. The developed method has been successfully applied to the determination of NSAIDs in urine samples of patients under their medication. Finally, the green character of the proposed method was evaluated using ComplexGAPI tool. The proposed method will pave the way for simper analysis of polar drugs by FPSE-GC-MS.

Analytical Chemistry: Tasks, Resolutions and Future Standpoints of the Quantitative Analyses of Environmental Complex Sample Matrices

Currently, the challenges that analytical chemistry has to face are ever greater and more complex both from the point of view of the selectivity of analytical methods and their sensitivity. This is especially true in quantitative analysis, where various methods must include the development and validation of new materials, strategies, and procedures to meet the growing need for rapid, sensitive, selective, and green methods. In this context, given the International Guidelines, which over time, are updated and which set up increasingly stringent “limits”, constant innovation is required both in the pre-treatment procedures and in the instrumental configurations to obtain reliable, accurate, and reproducible information. In addition, the environmental field certainly represents the greatest challenge, as analytes are often present at trace and ultra-trace levels. These samples containing analytes at ultra-low concentration levels, therefore, require very labor-intensive sample preparation procedures and involve the high consumption of organic solvents that may not be considered “green”. In the literature, in recent years, there has been a strong development of increasingly high-performing sample preparation techniques, often “solvent-free”, as well as the development of hyphenated instrumental configurations that allow for reaching previously unimaginable levels of sensitivity. This review aims to provide an update of the most recent developments currently in use in sample pre-treatment and instrument configurations in the environmental field, also evaluating the role and future developments of analytical chemistry in light of upcoming challenges and new goals yet to be achieved.

Sensitive detection of ferbam by coupling solid phase microextraction with surface enhanced Raman spectroscopy based on Au nano-glass capillary

In this study, we developed an innovative approach that combines solid phase microextraction (SPME) with surface-enhanced Raman spectroscopy (SERS) to detect pesticide ferbam rapidly. An Au nano-glass capillary was fabricated by coating template-freely synthesized three-dimensional network Au nanostructures (3D-NW AuNSs) on the roughened surface of glass capillary and used for SPME and SERS respectively. Significant Raman signals were obtained by the SPME-SERS method, followed by detection of ferbam in water and orange juice samples with only 1 min SPME process. Results showed that Au nano-glass capillaries could achieve the detection of ferbam with limit of detection of 0.05 μg/L, and coefficient of determination (R²) of 0.9913. The recovery of predicted results was in the range of 88.46-103.29% and the relative standard deviation (RSD) was 3.5-8.2%. This study demonstrated potential capability of the SPME-SERS method for rapid (within 1 min) and sensitive detection of organic compounds in complex matrices. The SERS-active Au nano-glass capillary is easy to carry and operate, and is expected to play a role in the detection of trace pollutants.

Fabric phase sorptive extraction combined with gas chromatography-mass spectrometry as an innovative analytical technique for the determination of selected polycyclic aromatic hydrocarbons in herbal infusions and tea samples

This study presents a fabric phase sorptive extraction (FPSE) protocol for the isolation and preconcentration of four selected polycyclic aromatic hydrocarbons from tea samples and herbal infusions, followed by their separation and quantification by gas chromatography-mass spectrometry (GC-MS). In FPSE, extraction of the target analytes is performed utilizing a flexible fabric substrate that is coated with a highly efficient sol–gel sorbent. In this work, eighteen different FPSE membranes were examined, with the highest extraction recoveries being observed with the sol–gel C₁₈ coated FPSE membrane. The main parameters that influence the adsorption and desorption of the PAHs were optimized and the proposed method was validated. The detection limits and the quantification limits were 0.08–0.17 ng mL⁻¹ and 0.25–0.50 ng mL⁻¹, respectively, for the different target compounds with a 10 mL sample. The relative standard deviations for intra-day and inter-day repeatability were less than 7.9% and 8.5%, respectively. The sol–gel C₁₈ coated FPSE membrane could be used for at least 5 subsequent sample preparation cycles. Finally, the proposed protocol was successfully employed for the determination of PAHs in a wide range of tea and herbal infusion samples.

A fabric phase sorptive extraction (FPSE) protocol for the isolation and preconcentration of four selected polycyclic aromatic hydrocarbons from tea samples and herbal infusions is presented, followed by their quantitative analysis by GC-MS.

Application of deep eutectic solvent-based extraction coupled with an S-CQD fluorescent sensor for the determination of pirimicarb in cereals

A novel deep eutectic solvent-based extraction and sulfur-doped carbon quantum dots (S-CQDs) serving as fluorescence probes to detect pirimicarb in cereals were established. The deep eutectic solvent was synthesized using choline chloride and butanediol, achieving direct and efficient extraction of pirimicarb residue in the cereals. The fluorescence quenching of S-CQDs was caused by the electrostatic interaction between the negatively charged S-CQDs and positively charged thiocholine, which was the hydrolysate of acetylthiocholine. The fluorescence of S-CQDs was enhanced as the activity of acetylcholinesterase (AChE) was inhibited by pirimicarb, achieving the detection of pirimicarb in the cereal samples. The limit of detection (LOD) was 0.006 μg mL^-1. The recovery ranged from 96.6% to 108.2%. This extraction and detection method of pirimicarb based on an environmentally friendly DES and S-CQD fluorescent sensor maintains good stability and convenience, offering a promising strategy for extracting and testing harmful substances in food samples.

Development of highly hydrophobic fabric phase sorptive extraction membranes and exploring their applications for the rapid determination of tocopherols in edible oils analyzed by high pressure liquid chromatography-diode array detection

Α novel, green, and facile fabric phase sorptive extraction (FPSE) prior to high pressure liquid chromatography with diode array detection (HPLC-DAD) methodology was developed for the efficient extraction and quantitative determination of tocopherols (α-, sum of (β+γ), and δ-) in edible oils. Among several highly hydrophobic FPSE membranes, sol-gel polycaprolactone-polydimethylsiloxane-polycaprolactone (sol-gel PCAP-PDMS-PCAP) coated polyester FPSE membrane was found as the most efficient in extracting tocopherol homologues from edible oil samples. To maximize the extraction efficiency of FPSE membrane, major parameters of FPSE including the membrane size, sample loading time, the choice of the appropriate elution solvent and the elution solvent volume, desorption time, and the influence of stirring were systematically optimized. The developed FPSE-HPLC-DAD methodology was validated and presented adequately low limits of detection (LODs) and limits of quantification (LOQs) over the ranges 0.05-0.10 μg/g, and 0.17-0.33 μg/g, respectively. The RSD% of the within-day and between-day assays were lower than 1.3, and 11.8, respectively, demonstrating good method precision. The trueness of the method was assessed by means of relative percentage of recovery and ranged between 90.8 and 95.1% for within-day assay, and between 88.7-92.8% for between-day assay. The developed methodology was applied in the analysis of edible oils.

Application of ZnS/S/S-RGO three-component nanocomposites in dispersive solid-phase microextraction coupled with ion mobility spectrometry for ultra-trace determination of multiclass pesticides

A fast, effective, and sensitive dispersive solid-phase microextraction method coupled with ion mobility spectrometry for the simultaneous determination of bendiocarb, butachlor, and diazinon was developed using zinc sulfide/sulfur/sulfur-doped reduced graphene oxide (ZnS/S/S-RGO) nanocomposites. ZnS/S/S-RGO three-component nanocomposites were synthesized through a single-step solvothermal procedure, and their properties were characterized by FT-IR, XRD, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and energy-dispersive x-ray spectroscopy (EDX). The influence of different parameters was optimized on the efficiency of the extraction including the type and the volume of desorption solvent, pH, type and the volume of buffer, the amount of absorbent, sorption and  desorption times. Under the optimal conditions, linear ranges were achieved 0.8-110, 1.0-110, and 0.5-100 ng mL^-1 with detection limits of 0.32±0.01, 0.40±0.02, and 0.27±0.02 ng mL^-1 for bendiocarb, butachlor, and diazinon, respectively. The method was employed for the ultra-trace determination of the three pesticides in water, rice, and soil samples with acceptable recovery values within the range 96.6±4.8-104.4±6.4%.

Designing a moderately hydrophobic sol-gel monolithic Carbowax 20 M sorbent for the capsule phase microextraction of triazine herbicides from water samples prior to HPLC analysis

The determination of triazine herbicides in water samples is of utmost importance, due to their persistence and excessive use. However, since the concentration of triazine pesticides in real samples is low, an extraction/preconcentration step is typically required. Capsule phase microextraction (CPME) is a recently introduced sample preparation technique in which highly efficient sol-gel sorbents are encapsulated in a tubular polymer membrane. This particular design integrates the filtration and stirring mechanism into one extraction device, enabling the application of CPME for in situ sampling. In this study, CPME coupled to high performance liquid chromatography-diode array detection (HPLC-DAD) was employed for the first time for the determination of six triazine herbicides (i.e., simazine, cyanazine, atrazine, prometryn, terbuthylazine and propazine) in water samples. Microextraction capsules containing a moderately hydrophobic sol-gel Carbowax 20 M sorbent provided the highest extraction efficiency towards the examined pesticides. The main parameters affecting the adsorption and desorption steps of the CPME procedure were investigated and optimized. Under the selected conditions, limits of detection (signal/noise = 3.3) were 0.15 ng mL^-1 for the target analytes. Moreover, the relative standard deviation for the within-day and between-days repeatability were less than 7.2% and 9.9%, respectively. The method was successfully applied to the analysis of mineral water, tap water, rainwater and lake water samples. The reported protocol could overcome the need for sample filtration prior to the sample preparation of the water samples, resulting in simplification of the overall sample handling, improved data quality with minimal loss of analytes and reduced sample preparation cost.

Hierarchical nanoarchitecture of zirconium phosphate/graphene oxide: Robust electrochemical platform for detection of fenitrothion

We report the rational design of nanocomposite with zirconium phosphate encapsulated on graphene oxide (ZrP/GO) for the highly sensitive and selective analysis of fenitrothion (FT). The characteristics of ZrP/GO nanocomposite are systematically analyzed by various in-depth electron microscopic, spectroscopic and analytical techniques. The ZrP/GO nanocomposite modified electrodes show better electrochemical response towards FT than other electrodes. The improved electrochemical activity of nanocomposite is attributed to large surface area, high conductivity, numerous active surface sites, GO nanosheets served as the conductivity matrix while preventing ZrP from agglomeration and the synergistic effect of ZrP and GO. Benefitting from the unique features, our fabricated sensor exhibits the superior performance in terms of wide working range (0.008-26 μM), appropriate peak potential (-0.61 V), low limit of detection (0.001 µM), high sensitivity (6 µA µM^-1 cm^-2) with the regression coefficient of 0.999. Additionally, the electrochemical sensor also displays good selectivity, excellent stability (99.6%), reproducibility (4.9%) and reusability (6.1%). The practical applicability of ZrP/GO sensor is shown by performing the detection of FT in water samples. These results clearly suggest that the ZrP/GO nanocomposite is an efficient electrode material for the future real-time environmental monitoring of FT.

Three-dimensional assembly and disassembly of Fe3O4-decorated porous carbon nanocomposite with enhanced transversal relaxation for magnetic resonance sensing of bisphenol A

The design and construction of a novel magnetic resonance sensor (MRS) is presented for bisphenol A (BPA) detection. The MRS has been built based on the core component of magnetic Fe₃O₄ nanoparticles (~ 40 nm), which were uniformly distributed in nanoporous carbon (abbreviated as Fe₃O₄@NPC). The synthesis was derived from the calcination of the metal organic framework (MOF) precursor of Fe-MIL-101 at high temperature. Fe₃O₄@NPC was confirmed with enhanced transversal relaxation with r₂ value of 118.2 mM^-1 s^-1, which was around 1.7 times higher than that of the naked Fe₃O₄ nanoparticle. This enhancement is attributed to the excellent proton transverse relaxation rate of Fe₃O₄@NPC caused by the reduced self-diffusion coefficient of water molecules in the vicinity of Fe₃O₄ nanoparticles in the nanoporous carbon. BPA antibody (Ab) and antigen (Ag)-ovalbumin (OVA) were immobilized onto the Fe₃O₄@NPC to form Ab-Fe₃O₄@NPC and Ag-Fe₃O₄@NPC, respectively. These two composites can cause the three-dimensional assembly of Fe₃O₄@NPC via immunological recognition. The presence of BPA can compete with antigen-OVA to combine with Ab-Fe₃O₄@NPC, thereby breaking the assembly process (disassembly). The difference in the change of the T₂ value before and after adding BPA can thus be used to monitor BPA. The proposed MRS not only revealed a wide linear range of BPA concentration from 0.05 to 50 ng mL^-1 with an extremely low detection limit of 0.012 ng mL^-1 (S/N = 3), but also displayed high selectivity towards matrix interferences. The recoveries of BPA ranged from 95.6 to 108.4% for spiked tea π, and 93.4 to 104.7% for spiked canned oranges samples, respectively, and the RSD (n = 3) was less than 4.4% for 3 successive assays. The versatility of Fe₃O₄@NPC with customized relaxation responses provides the possibility for the adaptation of magnetic resonance platforms for food safety development. The magnetic Fe3O4 nanoparticles are uniformly dispersed in the nanoporous carbon (Fe3O4@NPC), which derived from the calcinating of the metal organic framework (MOF) precursor of Fe-MIL-101. And the magnetic Fe₃O₄@NPCs are adopted for the construction of magnetic resonance sensor (MRS) for bisphenol A (BPA) detection.