The Application of Solid Phase Microextraction in the Analysis of Organophosphorus Pesticides in a Food Plant

Chen, Weiqi; Poon, Ka-Fai; Lam, Michael

doi:10.1021/es980294c

Cited by 34 publications

(17 citation statements)

References 32 publications

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“…Theoretical BDEs are determined from single point energy calculations at the B3LYP/6-311ϩG(2d,2p) level using the B3LYP/6-31G* optimized geometries. The agreement between theory and experiment is reasonably good for all complexes except Li ϩ (TMP hosphate esters are integral parts of many biologically active molecules ranging from nucleic acids, lipids, and ATP to pesticides and nerve agents [1][2][3]. Serving as link components in nucleic acids, phosphate esters connect thousands of base pairs to form large molecules that contain the genetic information.…”

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confidence: 71%

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A simple model for metal cation-phosphate interactions in nucleic acids in the gas phase: Alkali metal cations and trimethyl phosphate

Ruan

Huang

Rodgers

2008

J. Am. Soc. Mass Spectrom.

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Threshold collision-induced dissociation techniques are employed to determine the bond dissociation energies (BDEs) of complexes of alkali metal cations to trimethyl phosphate, TMP. Endothermic loss of the intact TMP ligand is the only dissociation pathway observed for all complexes. Theoretical calculations at the B3LYP/6-31G* level of theory are used to determine the structures, vibrational frequencies, and rotational constants of neutral TMP and the M ϩ (TMP) complexes. Theoretical BDEs are determined from single point energy calculations at the B3LYP/6-311ϩG(2d,2p) level using the B3LYP/6-31G* optimized geometries. The agreement between theory and experiment is reasonably good for all complexes except Li ϩ (TMP hosphate esters are integral parts of many biologically active molecules ranging from nucleic acids, lipids, and ATP to pesticides and nerve agents [1][2][3]. Serving as link components in nucleic acids, phosphate esters connect thousands of base pairs to form large molecules that contain the genetic information. These phosphate groups are deprotonated under physiological conditions. The resulting negative charges along the phosphate backbone are stabilized and neutralized by the binding of metal cations. Metal cations can and often do exert a significant influence on nucleic acid structure and genetic information transfer [4]. Metal cation binding reduces the repulsion between neighboring nucleotide units, and therefore influences the stabilization and structural dynamics of nucleic acids and lipids in membranes. For example, alkali and alkaline earth metal cations, including the most biologically important of these cations, Na ϩ and Mg 2ϩ , prefer to bind to a phosphate group rather than to the nucleobases or sugar moieties [5]. Mg 2ϩ is found to increase the melting temperature of DNA [6]. Metal cations may also be involved in the functioning of nucleic acids, e.g., metal cations are required for the proper functioning of all ribozymes [7]. Metal cation-nucleic acid interactions are currently of great interest because metal cations and metal cation-ligand complexes bind to DNA and regulate gene expression, act as drugs, or can be used as tools for molecular biology studies [8]. Hendry and Sargeson studied metal cation-promoted phosphate ester hydrolysis and found that the rate of hydrolysis is modulated by the size of the metal cation and the ease of formation of a four-membered chelate ring [9]. Dempcy and Bruice found a pentacoordinate intermediate for the catalysis of alkyl phosphate diesters [10]. Schneider and Kabelac et al. [11] studied the distribution of five metal cations (i.e., Na, and Zn 2ϩ ) and water around a negatively charged phosphate group from various crystal structures, and found that all of the cations prefer asymmetric monodentate coordination over bidentate coordination. Their ab initio calculations suggest that bidentate binding of these metal cations to an isolated phosphate group is preferred, but that the presence of even a single water molecule alters this preference. Ab...

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mentioning

confidence: 71%

“…hosphate esters are integral parts of many biologically active molecules ranging from nucleic acids, lipids, and ATP to pesticides and nerve agents [1][2][3]. Serving as link components in nucleic acids, phosphate esters connect thousands of base pairs to form large molecules that contain the genetic information.…”

mentioning

confidence: 99%

A simple model for metal cation-phosphate interactions in nucleic acids in the gas phase: Alkali metal cations and trimethyl phosphate

Ruan

Huang

Rodgers

2008

J. Am. Soc. Mass Spectrom.

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“…Organochlorine, organophosphorus and carbamate pesticides from tomato and cucumber in DI mode [55] has been employed. Organophosphorus pesticides was extracted from pear and apple in DI mode [56], strawberry, cherry and cherry juice in HS mode [57,58], C. coronaium plant in DI mode [59] and 13 different vegetables in HS mode [60] using 100 µm PDMS. Multiclass pesticides were also extracted from tomato in the DI mode with 100 µm PDMS (Guillet [61].…”

Section: Solid Phase Microextraction (Spme)mentioning

confidence: 99%

Recent Developments and Applications of Microextraction Techniques for the Analysis of Pesticide Residues in Fruits and Vegetables

Tan¹,

Abdulra’uf²

2012

Pesticides - Recent Trends in Pesticide Residue Assay

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“…82 Owing the frequently less than 100% partitioning of analytes into the fiber, the recovery concept of extraction is not necessarily an appropriate indicator in SPME. 83 However, recovery has traditionally been an indicator of accuracy in a method. Therefore, SPME may only be used in limited quantitative applications for pesticide residues, but it may become a prominent screening approach owing to its ease of use and potentially fast operation.…”

Section: Solid-phase Microextractionmentioning

confidence: 99%

Multiclass, Multiresidue Analysis of Pesticides, Strategies for

Lehotay¹

2000

Encyclopedia of Analytical Chemistry

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Strategies for multiclass, multiresidue analysis of pesticides depend on several factors that all derive from three fundamental considerations: (1) the need for the results; (2) the form and composition of the matrix; and (3) the time, resources, and technology available to the analyst. First, the need for the data dictates the quality assurance (QA)/quality control (QC) guidelines and the desired analytical figures of merit, such as limits of detection (LOD) and the accuracy and precision of the results. These needs also contribute to the choice of pesticide analytes, which sets the polarity range for the analysis. No single method can determine all pesticides in diverse matrices, so an overall strategy is often used to compartmentalize a series of approaches in order best to detect the targeted pesticides in an effective and efficient process. Second, the various types of matrices that are commonly analyzed for pesticide residues may affect the sample preparation approach employed in the analytical strategy. Common matrices for pesticide analysis consist of solids, liquids, and gases in applications associated with food, agricultural, environmental, and other sample types. Varying degrees of pesticide–matrix interactions in different materials require more or less stringent extraction procedures to separate the pesticides from the sample. Sample preparation in multiclass, multiresidue strategies frequently utilizes liquid–solid, liquid–liquid and other partitioning processes including those, such as pressurized fluid extraction (PFE), in which pressure and temperature of different fluids are controlled. Extracts often require cleanup to remove interfering co‐extracted matrix components prior to analysis. A variety of cleanup techniques based on a number of partitioning processes, such as liquid chromatography (LC), may be employed in an on‐line or off‐line fashion. Lastly, the sample extract is usually further separated and analyzed using one or more techniques. The majority of pesticides are analyzed by gas chromatography (GC) with mass spectrometry (MS) and/or element‐selective GC detectors. High‐performance liquid chromatography (HPLC) is often used in the analysis of thermally labile pesticides that are not amenable to GC analysis. Other alternatives for analysis of certain pesticide include capillary electrophoresis (CE) and immunoassays. Fundamentally, a high degree of selectivity helps in generating excellent analytical results, but the wide polarity range of analytes in multiclass, multiresidue methods (MRMs) for pesticides necessitates a great deal of effort to attain a high degree of selectivity. Trade‐offs and compromises are omnipresent in multiclass, multiresidue analysis of pesticides, and a host of strategies are available depending on how the analytical chemist prioritizes the analytical and practical considerations.

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The Application of Solid Phase Microextraction in the Analysis of Organophosphorus Pesticides in a Food Plant

Cited by 34 publications

References 32 publications

A simple model for metal cation-phosphate interactions in nucleic acids in the gas phase: Alkali metal cations and trimethyl phosphate

A simple model for metal cation-phosphate interactions in nucleic acids in the gas phase: Alkali metal cations and trimethyl phosphate

Recent Developments and Applications of Microextraction Techniques for the Analysis of Pesticide Residues in Fruits and Vegetables

Multiclass, Multiresidue Analysis of Pesticides, Strategies for

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