Development of novel solid phase extraction materials for pesticide residue analysis
Development of novel solid phase extraction materials for pesticide residue analysis
β-Cyclodextrin (βCD) has been immobilized on silica and Amberlite XAD resin bases and evaluated as selective material for use in solid phase extraction (SPE). This work focuses on the synthesis, characterization and applications of the SPE materials in the determination of pesticide residues.
A number of synthetic methods were employed for bonding βCD to silica and XAD-4 resin. βCD, methylated βCD and the mixed functionality of diol and βCD phases were prepared on a silica base using (3-isocyanatoproply)triethyoxysilane as a linker. βCD was also immobilized by adsorption onto Amberlite XAD-4 resin or by chemical linking onto silica-modified XAD-4.
The loadings of βCD on the modified silicas and XAD resins were qualitatively and quantitatively determined. Molish's test and a diphenylamine-aniline test confirmed the presence of βCD bonded on the solid phases. The βCD contents were colorimetrically determined using a newly developed phenol-sulphuric acid method. Silicas modified with βCD and the mixed functionality Diol-βCD showed little difference between their βCD loadings (17.4μmol and 16.7μmol βCD/g, respectively). Adsorption of βCD onto XAD resulted in material having a lower loading of βCD than the materials synthesised on a silica base. Infrared and Raman spectroscopy showed the presence of βCD on the silica surfaces. Elemental (CHN), gravimetric and thermogravimetric (TGA) analyses were together used to demonstrate the presence of organic material on the silica surface. The βCD loadings calculated from TGA and CHN data were in agreement with data obtained by the phenol-sulphuric acid colorimetric method. The ability of βCD to form inclusion complexes with a number of pesticides was assessed by TLC (thin layer chromatography), UV (ultraviolet spectrophotometry)., TGA and DSC (differential scanning calorimetry). TLC showed that for many pesticides the formation of such complexes is either kinetically very slow or that it may not occur. The addition of βCD to dichlobenil and triallate enhanced their UV absorption spectra, suggesting possible complex formation. The TGA and DSC characteristics of the atrazine-βCD "complex" were assigned to weak associations between βCD and atrazine rather than the presence of a true inclusion complex.
University of Southampton
1998
Al-Saad, Jalal Abdulla
(1998)
Development of novel solid phase extraction materials for pesticide residue analysis.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
β-Cyclodextrin (βCD) has been immobilized on silica and Amberlite XAD resin bases and evaluated as selective material for use in solid phase extraction (SPE). This work focuses on the synthesis, characterization and applications of the SPE materials in the determination of pesticide residues.
A number of synthetic methods were employed for bonding βCD to silica and XAD-4 resin. βCD, methylated βCD and the mixed functionality of diol and βCD phases were prepared on a silica base using (3-isocyanatoproply)triethyoxysilane as a linker. βCD was also immobilized by adsorption onto Amberlite XAD-4 resin or by chemical linking onto silica-modified XAD-4.
The loadings of βCD on the modified silicas and XAD resins were qualitatively and quantitatively determined. Molish's test and a diphenylamine-aniline test confirmed the presence of βCD bonded on the solid phases. The βCD contents were colorimetrically determined using a newly developed phenol-sulphuric acid method. Silicas modified with βCD and the mixed functionality Diol-βCD showed little difference between their βCD loadings (17.4μmol and 16.7μmol βCD/g, respectively). Adsorption of βCD onto XAD resulted in material having a lower loading of βCD than the materials synthesised on a silica base. Infrared and Raman spectroscopy showed the presence of βCD on the silica surfaces. Elemental (CHN), gravimetric and thermogravimetric (TGA) analyses were together used to demonstrate the presence of organic material on the silica surface. The βCD loadings calculated from TGA and CHN data were in agreement with data obtained by the phenol-sulphuric acid colorimetric method. The ability of βCD to form inclusion complexes with a number of pesticides was assessed by TLC (thin layer chromatography), UV (ultraviolet spectrophotometry)., TGA and DSC (differential scanning calorimetry). TLC showed that for many pesticides the formation of such complexes is either kinetically very slow or that it may not occur. The addition of βCD to dichlobenil and triallate enhanced their UV absorption spectra, suggesting possible complex formation. The TGA and DSC characteristics of the atrazine-βCD "complex" were assigned to weak associations between βCD and atrazine rather than the presence of a true inclusion complex.
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Published date: 1998
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Local EPrints ID: 463416
URI: http://eprints.soton.ac.uk/id/eprint/463416
PURE UUID: e8afeb7d-8751-4713-b49a-42cb6674f4f8
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Date deposited: 04 Jul 2022 20:51
Last modified: 04 Jul 2022 20:51
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Author:
Jalal Abdulla Al-Saad
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