aySample dissolution followed by liquid-liquid extraction (LLE) was a popular sample preparation technique for many years. However, traditional LLE is tedious, time-consuming, and costly. LLE requires several sample handling steps and can cause many difficulties, including phase emulsions, handling large solvent volumes, impure and wet extractions. Other classical sample preparation techniques include centrifugation, filtration, distillation, and precipitation. In the early 1970’s a simpler sample preparation technique was introduced, solid-phase extraction (SPE) [23]. A solid-phase extraction consists of bringing a liquid or gas sample in contact with a sorbent. The analyte is selectively adsorbed on the surface of the sorbent which is then easily separated from the sample. SPE has many advantages over the traditional LLE, including reduced analysis time through automation [24-28], decreased solvent usage and disposal, cleaner extracts, and no emulsions. The topic of SPE has been reviewed extensively [29-35]. SPE has become a widely used isolation technique with applications in different fields such as the quality control of pharmaceutical products, therapeutic drug monitoring and toxicology [36-44], pharmacokinetic and pharmacological studies, screening for forensic analysis [45-49], environmental analysis [50-58], food analysis [59-64], and drinking water analysis [65,66]
Conventional sample preparation techniques such as liquid-liquid extraction (LLE) and solid-phase extraction (SPE), are major sample preparation techniques. However, these techniques are often laborious, and dependent on large volumes of samples. In addition, they are not environmentally friendly due to wasteful organic solvents. Although SPE cartridges are widely and successfully used, difficulties can arise in their routine application. First, a rapid sample flow rate can cause kinetic effects in the bed of 40-µm particles and reduce the recovery of certain analytes [8]. Secondly, channeling can occur when an adsorbent is not packed tightly into the cartridge, resulting in an incomplete isolation of the analyte of interest. The development of SPE disks solves some of the problems encountered with cartridges, There are many disk configurations employed in SPE[9,19]. Solid phase extraction (SPE) disks provide many advantages over conventional liquid-liquid extraction techniques used in pesticide analysis from water less time required due to simultaneous extractions of multiple pesticides, decreased solvent volumes, and reduced disposal costs [20-22]
In recent years, the focus on development of green analytical procedures has prompted introduction of rapid and non-polluting techniques of sample preparation [7]. In fact, sample preparation is considered the most polluting phase of analysis, with its reliance, conventionally, on organic solvents, which are harmful to both humans and the environment. However, recently introduced miniaturized sample preparation techniques can be grouped in two main categories; extraction based on the use of sorbents and those based on the use of solvents [10,18]. Sorbent-based or, perhaps more correctly sorption-based micro extraction (SBME) including various modes of fibre-based solid-phase micro extraction (SPME), micro extraction by packed sorbent (MEPS), stir-bar sorptive extraction (SBSE), micro-solid phase extraction (μ-SPE),dispersive solid phase extraction(d-SPE) and dispersive micro solid phase extraction(d-µ SPE) have shown growing applicability [11-17]. in the follow is explanation of some mentioned procedure.
Dispersive solid phase extraction (DSPE) has risen as an alternative to conventional solid phase extraction. It was, for the first time, proposed by Anastassiades, Lehotay, Stajnbaher, and Schenck (2003) traditionally, SPE cleanup uses plastic cartridges containing 250–1000 mg sorbent material, vacuum manifolds, column preconditioning, solvent waste fractions, collection fractions, solvent evaporation steps, manual operation, and multiple solvents. Proper performance of SPE requires knowledge of the practice and theory of the technique, and requires training and careful attention on the part of the analyst. Common factors affecting reproducibility in SPE are difficulties with adjustment of the vacuum (and thus the flow rate), channeling ,and column going dry. SPE does not lend itself easily to automation, and automated SPE devices are quite expensive, require maintenance, and lack versatility for non routine applications. Certainly, column-based SPE has its advantages over alternative approaches, but it is still far from ideal in practice. By using a much smaller quantity of sorbent and avoiding the cartridge format, dispersive-SPE saves time, labor, money, and solvent compared with the traditional SPE approach. No preconditioning of cartridges is needed, minimal analyst training or attention is necessary, and the sorbent bed cannot dry out. Unlike column-based formats, all of the sorbent interacts equally with the matrix in dispersive-SPE, and a greater capacity per milligram sorbent is achieved (no breakthrough effects due to channeling) [67].
The first μ-SPE was reported in 2006 by Basheer et al. [4] in which multi-walled carbon nanotubes (MWCNTs) sorbent enclosed in a porous polypropylene (PP) membrane envelope was used to extract organophosporous pesticides from a sewage sludge sample. During extraction, μ-SPE device tumbles freely in the sample solution stirred by a magnetic stirrer, facilitating extraction. The porous membrane performs as a filter to prevent the extraction of interferences in sample matrix and protect the sorbent as well. Therefore, further cleanup of the extract was not necessary. The consumption of organic solvent was much less compared to conventional SPE. Furthermore, μ-SPE has also been demonstrated with advantages to overcome some drawbacks associated with SPME. Since the μ-SPE device consists of the sorbent enclosed in a porous polypropylene (PP) membrane envelop, its significant benefit is that a wider range of different sorbent materials can be used for the extraction of different analytes. The choice of a suitable sorbent is crucial to determine the selectivity of the extraction. In subsequent studies, different materials have been employed as sorbent by Basheer et al. for the μ-SPE of a variety of compounds in different samples, such as C18 sorbent to extract acidic drugs from water and carbamate pesticides in soil samples [5, 6].
organophosphorus pesticides is currently the most widely used chemical pesticides in agricultural production as a major means of production control crop pests and diseases, has an important role.
Organophosphorus pesticides greatly increased crop yields, it has brought economic benefits to human beings, but also cause harm to people's health and the external environment[3]. Environment remaining organophosphate pesticides will not only affect the function of the body, but also pose a potential hazard to human nervous system and other system function structure, and even reduce the body's immune function, Which can lead to cancer. [2] Organophosphorus pesticide residues has become one of the main sources of pollution in the world today. Today in the atmosphere, water, soil, food, vegetables and fruits, even in the inaccessible Arctic and Antarctic, organic residues pesticide composition are detected. . Organophosphorus pesticide residues has become one of the main sources of pollution in the world today. In order to protect human health and safeguard the environment, the need to strengthen the detection and prevention of organophosphorus pesticide residues.
In this work we synthesized CuO nanoplate-polyaniline as new µ- dispersive solid phase extraction
And use it in µ-DSPE process to measure agricultural pesticides.