Concentrations Of Methyl Parathion Research Articles

Surface-Initiated Reversible Addition-Fragmentation Chain Transfer Polymerization (SI-RAFT) to Produce Molecularly Imprinted Polymers on Graphene Oxide for Electrochemical Sensing of Methylparathion.

A nonenzymatic redox-responsive sensor was put forward for the detection of methylparathion (MP) by designing globular nanostructures of molecularly imprinted polymers on graphene oxide (GO@MIPs) via surface-initiated reversible addition-fragmentation chain transfer polymerization (SI-RAFT). Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), and small-angle X-ray scattering (SAXS) studies have confirmed the successful formation of receptor layers of MIPs on RAFT agent-functionalized GO sheets. The electrochemical signal with an amplified current response was attained because of the enhanced diffusion rate of ions at the interface provided by widening the pore size of the MIP film. The analytical response of GO@MIPs, validated by recording square-wave anodic stripping voltammetry (SWASV) at varying MP concentrations, followed the linear response between 0.2 and 200 ng/mL. Under optimized conditions, the sensor exhibited a limit of detection of 4.25 ng/mL with high selectivity over other interfering ions or molecules. The anti-interfering ability and good recovery (%) in food samples directed the use of the proposed sensor toward real-time monitoring and also toward future mimicking of surfaces.

Rational design of Boerhavia diffusa derived CoFe2O4-Carbon dots@Boehmite platform for photocatalysis and ultra trace monitoring of hazardous pesticide and UO22+ ions

In view of exploiting natural resources for designing of effectual materials in favor of detection and obliteration of water pollutants, a fluorescent nanomaterial (CDBHCF) based on biomass derived carbon dots (CDs) was constructed. The CDs and cobalt ferrite (CF) particles were anchored on boehmite (BH) which served as a support material for CDs. The CDBHCF nanocomposite was prepared via facile hydrothermal treatment for selective recognition of Methyl parathion (MP) pesticide and uranyl ions (UO22+). The corresponding structural, morphological and opto-electronic properties of the nanomaterials have been investigated by different physicochemical techniques. The fluorescent CDBHCF probe was employed to detect extremely low concentration of MP and UO22+ with detection limit of 22.4 nM and 4.4 nM, respectively. Ultimately, the proposed sensing platform was validated through real sample analysis. Besides, CDBHCF nanocomposite was utilized for photocatalytic abolition of Tetracycline (TC) in water samples. Initially, the impact of various operational parameters on the degradation efficiency, including catalyst dosage and initial pH were thoroughly examined. Under optimized conditions, the fabricated CDBHCF nanocomposite demonstrated excellent results for photocatalytic degradation of TC (92 % degradation in 120 min) under visible light illumination. Thus, the proposed strategy delivered an innovative insight for dual purpose of CDBHCF nanocomposite: as a fluorescent probe for real time monitoring and as a photocatalyst for removal of pollutants via simple photocatalytic degradation.

Silicon quantum dots based fluorescent probes for detecting methyl parathion pesticide residues in potato, tap water and Yellow River

In this paper, a novel ratiometric fluorescent probe based on silicon quantum dots (SiQDs) has been developed for the sensitive detection of methyl parathion pesticide residues. The silicon quantum dots were prepared by a simple hydrothermal reaction process using 3-Aminopropyltriethoxysilane (APTES) as silicon resource and were characterized by the analysis of transmission electron microscopy, FTIR spectroscopy, and X-ray photoelectron spectroscopy. The silicon quantum dots displayed characteristic blue fluorescence emission at 440 nm. Tyrosinase can catalyze the oxidation of tyramine to form dopamine. Then, dopamine can interact with silicon quantum dots and effectively change the position of its fluorescence emission for redshiftting to 540 nm. In the presence of organic phosphorus pesticides (OPPs), the activity of tyrosinase was inhibited, resulting in the inability to generate dopamine and the fluorescence emission at 440 nm remaining unchanged. As a model of organic phosphorus pesticides, methyl parathion (MP) was determined using this method, and the fluorescence intensity response values showed a good linear relationship with methyl parathion concentration in the range of 50–90 nM, with a detection limit of 0.149 nM. Due to its good performance of relative low detection limit, good selectivity and high reproducibility, this sensing system has been successfully applied to the detection of methyl parathion in environmental water samples and potato samples, which showed good prospects for application in the detection of organic phosphorus pesticide residues in more real samples.

Fabrication of highly conductive VXC-72R carbon nanoparticles decorated Zr (IV)-based metal-organic framework for highly sensitive detection of methyl parathion

A simple and efficient ultrasonic-assisted strategy was used to prepare the nanocomposite of Vulcan XC-72R carbon (VXC-72R) nanoparticles and Zr(IV)-based metal-organic framework (UIO-66) nanoparticles. For the multifunctional VXC-72R@UIO-66 nanocomposite, VXC-72R nanoparticles possessed good conductivity property and good dispersion, which were conductive to form the interconnected carbon conductive channels; UIO-66 nanoparticles could improve the accumulation ability of methyl parathion (MP) because of the high affinity of Zr-O groups with phosphoric groups. Moreover, the introduction of VXC-72R nanoparticles could effectively make up the conductivity property of UIO-66 nanoparticles. The VXC-72R@UIO-66/GCE sensor presented good MP detection performance with limit of detection (LOD) of 1.35 nM (Linear MP concentration range: 0.01–10 μM). When used for the detection of MP in juice samples, the VXC-72R@UIO-66/GCE sensor showed acceptable recoveries of 96.00–104.67 %.

An in situ one-step route for the synthesis of Fe3O4@ZIF-8 core-shells with a high-peroxidase-like performance for the colorimetric detection of methyl parathion

Methyl parathion (MP) is a broad-spectrum agricultural insecticide. Human exposure to MP can affect the nervous, cardiovascular, and hepatic systems. In this research, a core–shell Fe3O4@zeolitic imidazolate framework-8 (ZIF-8) is developed as a peroxidase mimic for the rapid and simple colorimetric detection of MP. Fe3O4 nanoparticles were wrapped with ZIF-8 by a hydrothermal method to obtain core–shell structural Fe3O4@ZIF-8 nanocomposites. The synthesized Fe3O4@ZIF-8 possessed mimetic properties and effectively catalyzed the conversion of transparent solution to blue upon the oxidation of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) by H2O2. Further, based on a classical reaction through acetylthiocholine chloride (ATCl) and cholesterol oxidase (ChOx), acetylcholinesterase (AChE) can generate H2O2, and that MP can exert an inhibitory effect on AChE. Within the range of 10 to 200 µg/L, the MP concentration demonstrated a remarkable linear response with the absorbance under optimum conditions, with a detection limit of 6.3 μg/L. Finally, the proposed approach enabled the detection of MP in cabbage. As an artificial peroxidase, Fe3O4@ZIF-8 demonstrated greater affinity for the substrate than horseradish peroxidase, which has a great application prospects in food safety and environmental safety.

Ultrasensitive electrochemical sensing platform based on Zr-based MOF embellished single-wall carbon nanotube networks for trace analysis of methyl parathion

In this work, a novel electrochemical sensor was designed based on Zr-based metal–organic framework (UIO-66) nanoparticles embellished single-wall carbon nanotube networks (SCN) for the detection of methyl parathion (MP). The synergistic combination of SCN and UIO-66 nanoparticles could fully exert each advantage to boost the MP electrochemical sensing analysis performance. SCN with one-dimensional hollow nanostructures formed three-dimensional interconnected carbon conductive networks, which possessed excellent conductive properties and acceptable specific surface area, enabling efficient transport of electrons and ions. UIO-66 nanoparticles with Zr-OH groups contributes and porous structure to the good affinity for phosphate groups on MP molecules, which enhanced the selective recognition and enrichment capability of sensing electrode towards MP. Under the multifunctional integration of SCN and UIO-66 nanoparticles, the SCN@UIO-66/GCE sensor could present satisfactory MP electrochemical detection performance (LOD: 8.05 nM, linear MP concentration range: 0.01–10 μM). The satisfactory practical property was realized at the SCN@UIO-66/GCE sensor with satisfactory recovery rates of 98.28–101.95 % and low RSD of 1.23–3.01 % for the electrochemical detection of MP in orange juice and lettuce samples.

A ratiometric fluorescence probe based on dual quantum dots for methyl parathion detection in agricultural products

Methyl parathion (MP) is an organic phosphorus pesticide widely used for pest control of various crops, however, the residual MP can enter the human body and damage the nervous system. Therefore, it is necessary to effectively monitor MP residues. Based on dual-fluorescent quantum dots, this study establishes a ratio fluorescence sensing platform for MP detection, wherein the probe is β-cyclodextrin (β-CD) modified molybdenum disulfide quantum dots (MoS2 QDs) called β-CD-MoS2 QDs. Under alkaline conditions, MP is hydrolyzed into p-nitrophenol (p-NP) and enters the hydrophobic cavity of β-CD, quenching the blue fluorescence of MoS2 QDs whose quenching degree of fluorescence intensity (I400) correlates with the concentration of MP, while the fluorescence intensity (I540) of gQDs remains unchanged and is selected as reference signal. The quantitative detection of MP is conducted by calculating the ratio of fluorescence intensities (I540/I400). The probe detected MP in the range of 0.05–25 ppm with a detection limit of 0.032 ppm which is proved to meet the requirements for biological sample detection according to the methodological validation results. The probe has been successfully applied for the detection of MP in apples and vegetables, confirming its applicability for MP detection in crops.

Enzyme-linked immunoassay for simultaneous detection of methyl parathion and sibutramine in apple cider vinegar.

Methyl parathion, a highly toxic, efficient, and persistent organophosphorus pesticide, is widely used in China. Sibutramine, a non-amphetamine central nervous system depressant, helps lose weight by disrupting hormone regulation, stimulating sympathetic nerves, and suppressing appetite. However, some unethical businesses fail to properly handle raw materials in foods like apple cider vinegar, leading to residual methyl parathion in apples or illegal excessive addition of sibutramine. Therefore, it is imperative to develop an immunoassay for the rapid detection of methyl parathion and sibutramine. The corresponding two haptens were prepared and coupled with the carrier proteins according to methyl parathion-sulfur-bovine serum protein (BSA)/chicken ovalbumin (OVA)-sibutramine (20 : 1 : excess, 15 : 1 : excess, 10 : 1 : excess, and 5 : 1 : excess), and sibutramine-BSA/OVA-methyl parathion (20 : 1 : excess, 10 : 1 : excess: 5 : 1 : excess, and 0 : 1 : excess). The result shows that the inhibition rate of the antibody obtained by methyl parathion-BSA/OVA-sibutramine (20 : 1 : excess) was higher than that of sibutramine-BSA/OVA-methyl parathion, which was 67.93%, and the concentration of methyl parathion was 8.65 ng mL-1 at this inhibition rate. Thus, methyl parathion-BSA/OVA-sibutramine (8.65 : 1 : excess) and the corresponding antibodies were selected for subsequent method establishment. By changing the concentration of the coating and antibody, the inhibition rate was found when the coating was 0.125 ng mL-1 and the antibody was diluted 4000 times. The antibody was used to develop a standard curve for the detection of sibutramine at the half-maximum inhibitory concentration (IC50) is 4.59 ng mL-1, the limit of detection (IC10) is 2.21 ng mL-1, the detection range is 2.89 to 7.28 ng mL-1, methyl p-phosphorus at the half-maximum inhibitory concentration (IC50) is 15.34 ng mL-1, the limit of detection (IC10) is 0.42 ng mL-1, the detection range is ng mL-1. Under these conditions, the recovery rate was between 88% and 102%, within reasonable limits, indicating the successful establishment of a rapid enzyme-linked ELISA assay.

Electrochemical detection of methyl parathion using zirconium dioxide@single-walled carbon nanotubes nanocomposite modified glassy carbon electrode

In this work, the multifunctional nanocomposite of zirconium dioxide (ZrO2) nanoparticles and single-walled carbon nanotubes (SCN) was prepared to modify the glassy carbon electrode (GCE) for the fabrication of ZrO2@SCN/GCE sensor. The fabricated nanocomposite electrochemical sensor was successfully used to achieve the efficient and sensitive detection of methyl parathion (MP). For the ZrO2@SCN nanocomposite, ZrO2 nanoparticles could promote the enrichment of MP molecules on the electrode surface of ZrO2@SCN/GCE sensor because of the interplay between Zr-O groups and phosphorus groups of MP molecules; SCN presented efficient one-dimensional charge transport channels, which achieved the excellent conductivity property of carbon material. Moreover, SCN could greatly compensate for the non-conductivity of ZrO2 nanoparticles. The functional combination of ZrO2 nanoparticles and SCN enhanced the electrochemical detection performance of MP. The ZrO2@SCN/GCE sensor exhibited good MP detection property with low limit of detection of 6.15 nM (pH = 7.0, MP concentration: 0.01–10 μM). The fabricated sensor also showed good practical application property for the detection of MP in real samples (Lake water and green tea).

On-site screening method for bioavailability assessment of the organophosphorus pesticide, methyl parathion, and its primary metabolite in soils by paper strip biosensor

An important public concern worldwide is soil pollution caused by organophosphorus pesticides and their primary metabolites. To protect the public’s health, screening these pollutants on-site and determining their soil bioavailability is important, but doing so is still challenging. This work improved the already-existing organophosphorus pesticide hydrolase (mpd) and transcriptional activator (pobR), and it first designed and constructed a novel biosensor (Escherichia coli BL21/pNP-LacZ) that can precisely detect methyl parathion (MP) and its primary metabolite p-nitrophenol with low background value. To create a paper strip biosensor, E. coli BL21/pNP-LacZ was fixed to filter paper using bio-gel alginate and sensitizer polymyxin B. According to the calibrations of the paper strip biosensor for soil extracts and standard curve, the color intensity of the paper strip biosensor collected by the mobile app may be used to compute the concentration of MP and p-nitrophenol. This method’s detection limits were 5.41 µg/kg for p-nitrophenol and 9.57 µg/kg for MP. The detection of p-nitrophenol and MP in laboratory and field soil samples confirmed this procedure. Paper strip biosensor on-site allows for the semi-quantitative measurement of p-nitrophenol and MP levels in soils in a simple, inexpensive, and portable method.

A sensitive electrochemical sensor based on the expired soybean-derived porous carbon for the determination of methyl parathion

In this work, a sensitive electrochemical sensor was designed by using the expired soybean-derived porous carbon (ESBPC) as electrode sensitizer, which was used to modify the glassy carbon electrode (GCE). The fabricated ESBPC/GCE sensor was successfully applied for the electrochemical detection of methyl parathion (MP). ESBPC was prepared by hydrothermal carbonization followed with high temperature potassium hydroxide (KOH) activation process. The obtained ESBPC sample presented obvious porous morphology, which could contribute to the improvement of charge transfer efficiency due to the interconnected porous carbon structure. Moreover, the porous morphology significantly increased the specific surface area of ESBPC, which promoted the improvement of adsorption capacity of carbon material towards MP molecules. As a result, the ESBPC sample presented high electrical conductivity and good adsorption capacity, which contributed to the improvement of electrochemical sensing performance. When used for the detection of MP, the ESBPC/GCE sensor presented sensitive MP determination performance with low limit of detection (LOD) of 11.7 nM (MP concentration: 0.05–10 μM). The DPV curve of ESBPC/GCE sensor showed obvious characteristic cathodic peak at − 0.12 V (vs. Ag/AgCl). The low relative standard deviation (RSD) of 0.6–1.2% could be obtained for the reproducibility and repeatability measurements, suggesting the good reproducibility and repeatability of the fabricated ESBPC/GCE sensor. In addition, the good anti-interference performance could be achieved with low RSD value of 2.6% at the ESBPC/GCE sensor.

Seasonal variations of low pesticides contamination and biomarker responses in marine bivalves from French estuaries

Biomarkers involved in detoxification process (GST), oxidative stress (SOD and MDA), immune response (Laccase) and neurotoxic disorders (AChE) were analysed in Pacific oysters and blue mussels collected from 4 locations within the Pertuis sea (France). Seasonal variations of total pesticide mean concentrations were found in seawater with metolachlor being the main pesticide measured (up to 32 ng/L). The majority of pesticide concentrations in sediment were below the LOD. Seasonal contamination differences were evidenced for chlortoluron, especially in mussels where concentrations reached 16 ng/g (wet weight) during the winter, in the Charente estuary, but no relationships with any of the biomarkers selected arisen. Actually, low concentrations of alpha-, beta-BHC and alachlor were correlated to GST activity, and low levels of hexachlorobenzene were linked to the AChE activity and MDA content in oysters. In mussels, low concentrations of methylparathion, parathion and beta-BHC were correlated to laccase.

Facile fabrication of Zr-based metal–organic framework/Ketjen black-carbon nanotubes composite sensor for highly sensitive detection of methyl parathion

A novel methyl parathion (MP) electrochemical sensor was fabricated from the multifunctional composite of Zr-based metal–organic framework (UiO-66) and Ketjen black-carbon nanotubes (KB-CNTs), which achieved the sensitive detection of MP in food samples. For the UiO-66/KB-CNTs composite, Zr-based UiO-66 with Zr-OH groups possessed good affinity for phosphate groups on methyl parathion molecules, which enhanced the selective recognition and enrichment capability towards MP, and KB-CNTs possessed three-dimensional interconnected carbon conductive network with synergistic point-line carbon conductive contact, which showed excellent electrical conductivity. Moreover, KB with pearl chain-like structure and more conductive contact points realized the full contact between KB-CNTs and UiO-66 with Zr-OH groups. The fabricated UiO-66/KB-CNTs/GCE sensor showed good MP detection performance with low limit of detection of 1.53 nM in linear MP concentration range of 0.005–12 µM. Moreover, the fabricated sensor showed good repeatability, reproducibility, and selectivity. A good practical feasibility can be achieved at the UiO-66/KB-CNTs/GCE sensor for the detection of MP in grape juice and apple juice samples (Recovery rate: 96.14–102.93, relative standard deviation: 2.17%-4.95%).

Design of methyl parathion electrochemical sensor based on expired mung bean-derived porous carbon modified glassy carbon electrode

ABSTRACT Herein, we reported a simple and sensitive methyl parathion (MP) electrochemical sensor based on the expired mung bean-derived porous carbon (MDPC)-modified glassy carbon electrode (GCE). For the fabricated MDPC/GCE sensor, MDPC presented three-dimensional (3D) interconnected porous carbon structure with good electrical conductivity, which provided more efficient charge transfer channels. Moreover, 3D interconnected porous carbon structure could help enhance the specific surface area and adsorption capacity of sensing electrode. Under the optimal conditions, the fabricated MDPC/GCE sensor showed good MP detection property with acceptable limit of detection of 13.2 nM (Linear MP concentration: 0.1–11 μM). Moreover, the fabricated MP electrochemical sensor presented good reproducibility and repeatability with relatively low relative standard deviation of 4.08% and 2.14%, respectively. The good practical performance could be realised at the fabricated MDPC/GCE sensor with satisfactory recovery (96.2–98.8%) and relative standard deviation (1.92–4.61) for the detection of MP in lake water sample.

Improved charge-transfer resonance in graphene oxide/ZrO2 substrates for plasmonic-free SERS determination of methyl parathion

This work reports a sensitive SERS substrate based on graphene oxide (GO) and quantum-sized ZrO2 nanoparticles (GO/ZrO2) for label-free determination of the organophosphate pesticide methyl parathion (MP). The enhanced light-matter interactions and the consequent SERS effect in these substrates resulted from the effective charge transfer (CT) mechanism attributed to synergistic contributions of three main factors: i) the strong molecular adherence of the MP molecules and the ZrO2 surface which allows the first layer-effect, ii) the relatively abundant surface defects in low dimensional ZrO2 semiconductor NPs, which act as intermediate electronic states that reduce the large bandgap barrier, and iii) the hindered charge recombination derived from the transference of the photoinduced holes to the GO layer. This mechanism allowed an enhancement factor of 8.78 × 104 for GO/ZrO2-based substrates, which is more than 5-fold higher than the enhancement observed for platforms without GO. A detection limit of 0.12 μM was achieved with an outstanding repeatability (variation ≤4.5%) and a linear range up to 10 μM, which is sensitive enough to determine the maximal MP concentration permissible in drinking water according to international regulations. Furthermore, recovery rates between 97.4 and 102.1% were determined in irrigation water runoffs, strawberry and black tea extracts, demonstrating the reliability of the hybrid GO/ZrO2 substrate for the organophosphate pesticides quantification in samples related to agri-food sectors and environmental monitoring.

Sn/MoC@NC hollow nanospheres as Schottky catalyst for highly sensitive electrochemical detection of methyl parathion

Developing electrode materials with excellent electrocatalytic properties for detecting pesticide residues plays a vital role in the safety of agricultural products and environmental applications. Herein, we designed a new electrochemical sensor on the basis of N-doped carbon hollow nanospheres modified with Sn/MoC Schottky junction (Sn/MoC@NC) for methyl parathion (MP) detection. The Sn/MoC@NC was prepared by self-assembled polymerization-anchoring strategy and high-temperature carbonization design. Sn/MoC Schottky junction and hollow nanosphere structure endow Sn/MoC@NC with a larger surface area, more active sites, and faster electron transfer, which is beneficial to enhancing its electrocatalytic performance. The structural characterizations and physicochemical properties of Sn/MoC@NC were explored through various microscopy, spectroscopic and electrochemical techniques. The experimental results confirmed that the calibration curve for current and MP concentration (0.05–10 μg/mL) was available under optimized conditions, and the sensitivity and detection limit were respectively determined to be 9.02 μA μM1 cm2 and 8.9 ng/mL. Furthermore, the constructed sensor displayed excellent selectivity, repeatability, and stability, which qualified it for use in detecting MP in grapes and tap water with satisfactory recovery. This work may provide some interesting prospects for constructing high-performance electrocatalysts for MP detection.

Effects of additives on the performance of a laser-induced graphene sensor modified with ZrO2 nanoparticles for OP detection.

In this study, a simple and portable electrochemical sensor based on laser-induced graphene (LIG) has been developed to systematically investigate the feasibility of LIG as an electrode to detect organophosphorus pesticides (OPs). It proves that the LIG-based electrode has a relatively high electrochemically active surface area (ECSA) and heterogeneous electron transfer (HET) of 0.100 cm2 and 0.000825 cm s-1, respectively. In addition, zirconium dioxide nanoparticles (ZrO2 NPs) have been modified on the electrode with three different binders, β-cyclodextrin (β-CD), chitosan (CS) and Nafion, to improve the adsorption capacity of the electrode toward OPs, and the effect of the binders on the performance of the as-fabricated sensor has been investigated in detail. The results show that β-CD increases not only the electrochemically active surface area of the electrode but also the redox peak current of methyl parathion (MP). To evaluate the sensitivity of the sensor, differential pulse voltammetry (DPV) curves have been tested in solutions containing different concentrations of MP using ZrO2-β-CD/LIG as an electrode, which shows a detection range of 5-200 ng ml-1 and a detection limit of 0.89 ng ml-1. In summary, the LIG-based sensor has a low detection limit, high sensitivity and good interference resistance, and thus has tremendous potential for the detection of pesticides in the environment.

Electrochemical sensing platform based on graphitized and carboxylated multi-walled carbon nanotubes decorated with cerium oxide nanoparticles for sensitive detection of methyl parathion

We proposed a low-cost ultrasonic-assisted strategy to prepare the graphitized and carboxylated carbon nanotubes (GR-MWCNTs-COOH) and cerium oxide (CeO2) nanoparticles nanocomposite, which was applied to fabricate the GR-MWCNTs-COOH@CeO2/GCE sensor for the electrochemical detection of methyl parathion (MP). GR-MWCNTs-COOH with graphitization and carboxylation showed excellent conductivity property, large surface area, and gratifying hydrophilicity. Graphitization enhanced the electrical conductivity of MWCNTs, and carboxylation promoted the homogeneous dispersion of MWCNTs. The double-functionalization of MWCNTs helped form the interconnected carbon nanotubes conductive network. CeO2 nanoparticles with good catalytic ability possessed high enrichment capability of MP because of the good affinity between CeO2 and phosphate groups. Moreover, the double-functionalized GR-MWCNTs-COOH not only promoted the uniform dispersion of CeO2 nanoparticles but also compensated for the poor electrical conductivity of CeO2 nanoparticles. The GR-MWCNTs-COOH@CeO2/GCE sensor presented a low detection of limit of 0.0285 μM (MP concentration range: 0.01–10 μM). The satisfactory reproducibility, repeatability, and anti-interference were obtained at the fabricated nanohybrid sensor. When applied for the MP determination in spinach and cabbage samples, the low RSD values of 1.71–4.25% and satisfactory recoveries of 95.8–100.7% could be achieved at the GR-MWCNTs-COOH@CeO2/GCE sensor. This work provided an important reference for the design of high-performance MP sensor.

Anopheles gambiae Larval Development and Toxicity’s Reduction of Conventional Agriculture Insecticides in the Laboratory Conditions

Background: Vector control of Malaria is mainly made by using impregnated bed nets and insecticides pulverizations indoor or/and outdoor. Besides, appearance and development of resistance’s phenomenon among mosquito populations to insecticides, constitute a significant obstacle this fighting.
 Aims: To highlighting a neutralization phenomenon of three insecticides (methyl-parathion, dimethoate and cypermethrin) during development of the Anopheles gambiae s.s. larvae.
 Methodology: Two setups followed one after the other were designed. In setup 1, four concentrations (with four replicates each) were freshly prepared and independently received a first batch of 100 first instars An. gambiae s.s. After emergence of adults from this first batch, the same test media were simply filtered and received a second batch of first instars larvae to make setup 2. Three endpoints were measured in this study: the duration of larval phase, the larval mortality, and the size of adults.
 Results: The development duration and mortality of larvae decreased significantly at setup 2 with cypermethrin and methyl-parathion. Thus, the duration of larval stage decreased from 10.18 days at setup 1 to 7.84 days at setup 2 for 0.010 µg/l (highest concentration) with cypermethrin and from 10.20 days at setup 1 to 8.27 days at setup 2 for 0.144 µg/l (highest concentration) with methyl-parathion. The larval mortality dropped from 79.32 % at setup 1 to 12.00 % at setup 2 for the highest concentration of cypermethrin and from 76.42 % at setup 1 to 12.50 % at setup 2 for the highest concentration of methyl-parathion. While adults size significantly increased in setup 2. For males, wing’s length increased from 3.28 mm at setup 1 to 3.49 mm at setup 2 for the highest concentration of cypermethrin, from 3.31 mm at setup 1 to 3.49 mm at setup 2 for the highest concentration of methyl-parathion. In female, wing’s length increased from 3.52 mm at setup 1 to 3.68 mm at setup 2 for the highest concentration of cypermethrin, from 3.49 mm at setup 1 to 3.68 mm at setup 2 for the highest concentration of methyl-parathion.
 Conclusion: This work shows that mosquito larvae, especially An. gambiae are able to modify breeding medium to improve its fitness during their development.

Rapid determination of methyl parathion in vegetables using electrochemical sensor fabricated from biomass-derived and β-cyclodextrin functionalized porous carbon spheres

Porous carbon spheres (PCS) derived from expired sugarcane juice (SJ) and modified with β-cyclodextrin (β-CD) were used for the fabrication of SJPCS@β-CD/GCE sensor with glassy carbon electrode (GCE) to detect methyl parathion (MP). SJPCS with interconnected porous structure exhibits excellent electrical conductivity, strong adsorption property, and high specific surface area, while β-CD with molecular recognition property achieves the uniform dispersion of SJPCS and promotes the recognition and adsorption of MP molecules. Thanks to the synergistic combination of SJPCS and β-CD, the SJPCS@β-CD/GCE sensor exhibited respectable MP determination performance with low limit of detection of 5.87 nM in the MP concentration range of 0.01–10 µM. For the MP detection in vegetables (onion, cabbage, spinach), the fabricated sensor showed good practicability with adequate relative standard deviation of 1.06% to 4.25% and satisfactory recoveries of 96.5 to 100.5%. A promising strategy for the rapid determination of methyl parathion in food products was developed.