Sharif Digital Repository

Methiocarb [3,5-dimethyl-4-(methylthio) phenyl methylcarbamate] is an N-methylcarbamate with neurotoxic action. Because carbamate pesticides are acetylcholinesterase inhibitors, they are considered to be carcinogens and mutagens. Methiocarb pesticide is widely used throughout the world particularly effective as fungicides, insecticide and bird repellent. To prevent its harmful effects on animals, humans, and the environment, it is of crucial importance to develop simple and sensitive methods for in-situ detection of methiocarb. This research describes a simple and low-cost method for on-site monitoring of methiocarb insecticide. Gold nanoparticles (AuNPs) aggregation caused by methiocarb,... 

In this study, a new strategy based on chemometrics and extraction method of Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) combined with dispersive liquid–liquid micro-extraction (DLLME) in addition gas chromatography-flame ion detector (GC-FID) has been developed for the determination of ten pesticides in complex samples (such as tap water and milk).In this regard, experiments were designed, modeled and optimum condition was achieved by using central composite design (CCD), backward multiple linear regression (MLR) and Nelder-Mead simplex optimization. On this matter, 36 experiments for 5 extraction factors in 5 levels were generated. Also, multi-response optimization using... 

There is an increasing need for food by the growth of population. To meet this need, the use of pesticides is increasing. Among pesticides organophosphorous compounds are the ones with the most usage. Liquid and gas chromatography are commonly used to measure orghanpphosphrous pesticides. These methods are relatively time consuming and require a tedious sample preparation.
Herein we report a sensitive colorimetric method for detection and measurement of Azinphos methyl, based on unmodified gold nanoparticles aggregation and changes in plasmonic band. Azinphos methyl, containing different soft acidic groups acts as a bridge, causes aggregation, and changes in plasmonic band. Changes in... 

Development of simple and rapid approaches for identification of pesticides has been known as a critical demand, due to the broad usage of pesticides and their harmful effects on mammals. Herein, we have introduced a silver nanoparticle (AgNP) based colorimetric sensor array for simultaneous identification of Azinphosmethyl (AM) and Phosalone (PS). In the presence of the target pesticides, unmodified AgNPs at various pHs (4.5, 5.5 and 9.5) showed different aggregation behaviours. As a result of aggregation, the color and UV-Vis spectra of AgNPs changed which led to distinct patterns for AM and PS. The aggregation induced spectral changes of AgNPs were used to identify AM and PS with the help... 

Pesticides are broadly applied in croplands, glasshouses, and orchards in order to increase agricultural products and their quality. Among the variety of pesticides, organophosphorus pesticides (OPs), possessing high insecticidal activity, acute toxicity and relatively short environmental persistence, have been widely used for pest control in agriculture. However, this effect might lead to adverse health impacts or death for mammals and humans. Thus, even at trace levels, it is of great importance to develop a simple, sensitive, inexpensive and real-time detection method for monitoring the levels of pesticides in the environment, foodstuffs and biological samples. The integration of metallic... 

The main approach of this thesis is the study of metal- organic frameworks (MOFs) performance as extractive phases in sample preparation methods. Hence, various MOFs were synthesized to investigate the roles of sorbent properties such as surface areas, pore sizes and shapes, interaction types, bonds and building units in extraction procedures of analytes. The prepared sorbents in conjugation with gas chromatography- mass spectrometry (GC-MS) were applied to determination of the environmental pollutants like chlorobenzenes, benzene derivatives (BTEX), polyaromatic hydrocarbons (PAHs) and residues of agriculture herbicides.In the first work, considering studying the roles of the sorbent pore... 

Due to the widespread use of pesticides and their harmful effects on humans and wildlife, monitoring their residual amounts in crops is critically essential but still challenging regarding the development of high-throughput approaches. Herein, a colorimetric sensor array has been proposed for discrimination and identification of triazole fungicides using monometallic and bimetallic silver and gold nanoparticles. Aggregation-induced behavior of AgNPs, AuNPs and Au-AgNPs in the presence of four triazole fungicides produced a fingerprint response pattern for each analyte. Pattern recognition methods, including linear discriminant analysis (LDA) and hierarchical cluster analysis, have been... 

There is great attention in developing rapid and straightforward methods for the identification of various pesticides that are usually used simultaneously in agricultural products. It is due to the extensive use of a diverse class of pesticides in agricultural products and their high toxicity which causes serious diseases in the human body. In the current study, a non-enzymatic sensor array has been developed for the identification and discrimination of five different pesticides belong to diverse classes including organophosphate, carbamate, and bipyridylium. For this aim, gold nanoparticles with two different capping agents consisting of citrate and borohydride were used as sensing... 

In this research, Cu-TATAB/Polyurethane (PU) nanocomposite fibers were prepared via electrospinning method in order to increase the overall extraction efficiency. The incorporation of Cu-TATAB, as a metal organic framework (MOF), in the synthesized nanocomposite contributed to the enhanced efficiency. The prepared sorbent was implemented for the thin film microextraction (TFME) of organochlorine species and their determination was subsequently performed by gas chromatography-mass spectrometry (GC-MS). To achieve the maximum efficiency of the synthesized sorbent, the parameters of MOF percentage in nanocomposites, solvent type and volume, desorption time, solution ionic strength and... 

In this work, a biocompatible sorbent based on halloysite nanotubes-zein bionanocomposite for direct-immersion thin film microextraction (DI-TFME) is introduced. Zein as a biodegradable, low cost and accessible polymer was used to prepare a flexible thin film with the possession of different interactions and good adsorption capacity. To improve the mechanical and chemical resistance of the film, halloysite nanotubes were combined with zein to prepare the thin film sorbent. The film was used for TFME of 16 pesticides from different chemical classes, including organochlorines and organophosphates followed by gas chromatography with electron capture detector (GC-ECD). To achieve the maximum... 

The use of myriad pesticides in agriculture crops has promoted the demand of developing rapid and sensitive probes for the detection and discrimination of diverse pesticides, which are usually used together. In this work, a colorimetric sensor array has been designed for identification and discrimination of Thiometon (TM) and Phosalone (PS) as organophosphate pesticides and Prothioconazole (PC) as a triazole pesticide. For this purpose, two different plasmonic nanoparticles including unmodified gold nanoparticles (AuNPs) and unmodified silver nanoparticles (AgNPs) were used as sensing elements. The principle of the proposed strategy relied on the aggregation of AuNPs and AgNPs through the... 

Novel high-throughput device and their applications as the microextraction systems for pesticide multiresidue determination is the centre of this research. 96 extracting unit based on solid phase microextraction and micro-Solid phase extraction were constructed and applied for high-throughput extraction.
In the first work, a high-throughput SPME on 96-well plate together with gas chromatography-mass spectrometry was developed for the determination of pesticide residues in cucumber samples. A home-made Teflon block consisting ninety-six holes was constructed to 96 SPME fibers being positioned in. SPME fibers consisted of stainless steel rods with a 1.0 cm polydimethylsiloxane tubing...