A novel and sensitive kinetic method for the determination of malathion using chromogenic reagent

Cross-regional scale studies of organochlorine pesticides in air in China: Pollution characteristic, seasonal variation, and gas/particle partitioning

Few simultaneous studies of organochlorine pesticides (OCPs) in the atmosphere have been conducted across Southeast and Northeast China, and no data on the gas/particle (G/P) partitioning behaviors of several current-use OCPs are available. In this study, a one-year synchronous monitoring program was conducted for OCPs in Chinese atmosphere spanning 30° latitude and 60 °C temperature. A total of 111 pairs of gas and particle samples were collected from Mohe and Harbin in Northeast China and from Shenzhen in Southeast China. The detection frequency for 66.7 % of the OCPs exceeded 80 %, indicating their prevalence in the atmosphere. The concentrations of individual OCPs spanned six orders of magnitude, indicating different pollution levels. Highest levels of hexachlorobenzene were observed at all sites. Banned OCPs were found predominantly in secondary distribution patterns, whereas current-use OCPs were dominated by primary distribution patterns. In Harbin and Mohe, the concentrations of OCPs were highest in summer, followed by autumn and winter. No obvious seasonal variation was observed in Shenzhen associated with different cultivation types. At all three sites, OCPs were predominantly found in the gas phase, and higher percentages of particle-phase OCPs were observed in Harbin and Mohe than in Shenzhen. In this study, G/P partitioning models were used to study the G/P partitioning mechanism of OCPs. The Li-Ma-Yang model provided the most accurate prediction of the G/P partitioning behavior of OCPs with high molecular weights and low vapor pressures, particularly at low temperatures. However, OCPs with lower molecular weights and higher vapor pressures were predominantly in the equilibrium state, for which the Junge-Pankow model was suitable. This systematic cross-scale study provides new insights into pollution, G/P partitioning, and the environmental behavior of OCPs in the atmosphere.

Peptide nanotube functionalized molecularly imprinted polydopamine based single-use sensor for impedimetric detection of malathion

In the present study, a peptide nanotube functionalized polydopamine (p-Dop) based molecularly imprinted (MIP) sensor system was constructed, characterized, and studied for the impedimetric sensing of an organophosphorus pesticide, malathion (MLT). Electropolymerization in the presence of a template (MLT) was utilized as a convenient and effective strategy to generate imprinted p-Dop films on peptide nanotubes (PNTs) modified graphite electrodes (PGEs). Upon the removal of template, the adsorption of MLT on the specific cavities formed in the MIP film was tracked using electrochemical impedance spectroscopy (EIS). To attain optimal sensor response, experimental conditions, such as film thickness, analyte/functional monomer ratio, and desorption/adsorption time, were analyzed. The obtained MIP(p-Dop)-PNT-PGE sensor exhibited high sensitivity for electrochemical MLT analysis with a wide dynamic detection range of 13 pg mL^-1 - 1.3 µg mL^-1 and a LOD of 1.39 pg mL^-1. The combination of a bio-inspired p-Dop-based MIP with the EIS technique allowed excellent sensitivity and selectivity toward MLT sensing which also yielded high recoveries in real samples. The success of this research strategy in real samples revealed its potential for various future environmental applications.

Application of chitosan-alginate bio composite for adsorption of malathion from wastewater: Characterization and response surface methodology

Agricultural effluents in aqueous media have caused serious threats due to adversely affect human health and the ecosystem. In this study, the low-cost easily accessible chitosan-alginate adsorbent was prepared for the removal of malathion from agricultural effluents using microemulsion method. The adsorbent was characterized using scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The optimum experimental conditions, including adsorbent dosage (0.05-0.25 g), contact time (5-25 min), and concentration of malathion (5-25 mg L^-1) at five levels were studied using the composite central design (CCD) based on the response surface methodology (RSM). The highest removal percentage was obtained 82.35 with an adsorbent dosage of 0.18 g, contact time of 20 min, and initial concentration of 10 mg L^-1. The analysis of variance (ANOVA) was applied to assess the significance and adequacy of the model. The results revealed that quadratic model was proper for the prediction removal of malathion. The adsorption kinetics and isotherms were examined under optimal conditions. The Langmuir with a coefficient of determination (R²) = 0.99 and pseudo-second-order with R² = 0.99 were achieved as the best isotherm and kinetic models, respectively. The results showed that the chitosan-alginate biopolymer can be effective and affordable adsorbent for the removal of malathion from aqueous solution.

A fuzzy cognitive map approach to predict the hazardous effects of malathion to environment (air, water and soil)

Malathion is an organophosphorus insecticide and pesticide commonly used in crops and residential applications. The negative effects of Malathion on human health and ecosystems are of great concern. In this work, a mathematical model pivot on Fuzzy Cognitive Map (FCM) is used to analyse the causes and hazardous effects of Malathion to the environmental components (air, water and soil). Based on expert's opinion the possible factors that cause damage to health and ecosystems due to Malathion is identified, which serve as the input to the FCM. The FCM mathematically establishes the causal relation between these factors. The mathematical simulation is done by Python Programming. This approach can be used to study the interdependencies between the adverse effects of any pesticide in human health and environment due to prolonged exposure.

Highly sensitive and selective determination of malathion in vegetable extracts by an electrochemical sensor based on Cu-metal organic framework

This article demonstrates the first application of a copper-based porous coordination polymer (BTCA-P-Cu-CP) as a carbon paste electrode (CPE) modifier for the detection of malathion. The electrochemical behavior of BTCA-P-Cu-CP/CPE was explored using cyclic voltammetry (CV) while chrono-amperometry methods were applied for the analytical evaluation of the sensor performance. Under optimized conditions, the developed sensor exhibited high reproducibility, stability, and wide dynamic range (0.6-24 nM) with the limits of detection and sensitivity equal to 0.17 nM and 5.7 µAnMcm^-1, respectively, based on inhibition signal measurement. Furthermore, the presence of common coexisting interfering species showed a minor change in signals (<4.4%). The developed sensor has been applied in the determination of malathion in spiked vegetable extracts. It exhibited promising results in term of fast and sensitive determination of malathion in real samples at trace level with recoveries of 91.0 to 104.4%. (RSDs < 5%, n = 3). A comparison of the two studied techniques showed that the HPLC technique is unable to detect malathion when the concentration is lower than 1.8 µM while 0.006 µM is detected with appropriate RSDs 0.2-5.2% (n = 3) by amperometric method. Due to the high sensitivity and selectivity, this new electrochemical sensor will be useful for monitoring trace malathion in real samples.

Preparation of malathion MIP-SPE and its application in environmental analysis

Malathion is an organophosphorous insecticide for controlling insects on fruits and vegetables, miscellaneous household insects, and animal parasites. It is important to develop highly efficient and selective pre-treatment method for analyzing malathion residues in environment and samples from agricultural products based on the molecularly imprinted polymers (MIPs). In this study, we developed a tailor-made MIP method with highly specific recognization to the template. The MIPs were prepared using malathion as a template, methacrylic acid (MAA) as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as a crosslinker, azodiisobutyronitrile (AIBN) as an initiator, and the acetonitrile-chloroform (1:1, v/v) as a porogen. The molecular recognization mechanism of malathion and MAA was evaluated by molecular simulation, ultraviolet spectrometry (UV), and (1)H-nuclear magnetic resonance ((1)H-NMR). MAA interacted specifically with malathion by hydrogen bond with a ratio of 2:1. The MIPs exhibit a high affinity, recognition specificity, and efficient adsorption performance for malathion. The Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), surface area and porosimeter analyzer, thermogravimetric/differential thermal analyzer (TG/DTA) were used to characterize the properties of MIP. The malathion residues in soil, tap water, and cabbage were cleaned up by MIP-SPE, detected quantitatively using GC-FPD, and confirmed by GC-MS/MS. The limits of tap water, soil, and cabbage were confined to 0.001 mg L(-1), 0.004 and 0.004 mg kg(-1), respectively. The spiked recoveries of malathion were 96.06-111.49% (with RSD being 5.7-9.2%), 98.13-103.83% (RSD, 3.5-8.7%), and 84.94-93.69% (RSD, 4.7-5.8%) for tap water, soil, and cabbage samples, respectively. Thus, the method developed here can be used effectively in assessing malathion residues in multiple environmental samples. The aim of the study was to provide an efficient, selective, and accurate method for analyzing malathion at trace levels in multiple media.