Selahle, S. K.Madala, N. E.Tavengwa, N. T.Mokgehle, T. M.Musarurwa, Herbert2026-06-302026-06-302026-05-19Musarurwa, H. 2026. Development of greener preconcentration and extraction techniques using emerging solvents and alternative sorbents for pesticide analysis. . .https://univendspace.univen.ac.za/handle/11602/3320Ph. D. in ChemistryDepartment of ChemistryThe increase in the human population has placed a serious strain on global food security. In an effort to restore food security, the agricultural sector has increased its use of pesticides to mitigate pest damage to crop yields. As a result, pesticides are widely present in food products and the environment, posing serious health risks. The problem is aggravated by the fact that pesticides can have detrimental effects on living organisms even at trace concentrations. This realization prompted regulatory agencies and food safety authorities to place significant emphasis on developing effective green sample preparation techniques for the enrichment of pesticides prior to instrumental analysis. Thus, various green micro-extraction techniques, such as Dispersive Liquid-Liquid Microextraction (DLLME), Stir Bar Sorptive Extraction (SBSE), Thin Film Microextraction (TFME), and Quick Easy Cheap Effective Rugged Safe (QuEChERS), have been developed. Most of these techniques use organic solvents at microliter levels. Some organic solvents are toxic and persistent in the environment. Consequently, they may enter food chains, where they may undergo bioaccumulation, leading to concentrations exceeding the maximum allowable limits. Thus, the toxicity of organic solvents is a major factor that motivated the development of microextraction techniques that use alternative green solvents in this research. On the other hand, the commercial sorbents used in different formats of solid phase microextraction are prohibitively expensive, and some are not eco-friendly. This puts a deep dent in the greenness of these micro-extraction techniques. The environmental sustainability of microextraction techniques can be enhanced by utilizing green, emerging solvents and sorbents, which is the primary focus of this study. The successive paragraphs summarize the findings of this study. Firstly, a novel medicine dropper-assisted solvent bar micro-extraction (MD-SBME) method was developed, utilizing the meltdown layer of a facemask (MLF) as a solvent holder. A hydrophobic natural deep eutectic solvent (NADES) made from thymol and menthol was used as the extraction solvent during the MD-SBME analysis of imidacloprid pesticide in fruit samples. Under the optimum conditions, detection and quantification limits were in the range of 0.007 – 0.02 μg g-1 and 0.02 – 0.069 μg g-1, respectively. The correlation of determinations (R2) for pineapple, pear, and apple samples were 0.9986, 0.9982, and 0.9973, respectively, and the extraction recoveries ranged from 72 – 110%. Good precision was achieved when the developed method was applied to real sample analysis, with all %RSD values less than 5%. The greenness of the MD-SBME technique was evaluated using the ComplexMoGapi algorithm, yielding a total score of 85. A total score of 65 was obtained when the practicality of the MD-SBME procedure was evaluated using the BAGI metric tool. Thus, the technique has good greenness and practicality profiles. Secondly, a novel chemical mop-based solvent bar micro-extraction (CM-SBME) method was developed, utilizing a polyester dish sponge (PDS) as the solvent holder for extraction. The limits of detection of the pesticides in the milk samples, under optimal conditions, were found to be in the range of 0.014 –0.03 mg L-1. The limits of quantification for the pesticides in the milk samples ranged from 0.045 to 0.096 mg L-1, while percentage extraction recoveries ranged from 72% to 90% for glyphosate and from 72% to 95.6% for fenitrothion. The CM-SBME procedure was evaluated using the Blue Applicability Grade Index (BAGI) and the Analytical Greenness Metric for Sample Preparation (AGREEprep) algorithms to assess practicality and greenness, respectively. Overall scores of 0.71 and 62.5 were obtained for AGREEprep and BAGI, respectively. These were relatively good scores, indicating that the developed CM-SBME procedure had a favorable green profile and practicality. Lastly, deep eutectic solvents (DESs) were utilized in this research to modify cellulose acetate cigarette filters (CFs), which were then employed as adsorbents during microextraction by packed sorbent (MEPS) for chlorpyrifos and fenitrothion in vegetable samples. Under optimum conditions, the developed DES-modified CF–based MEPS method was used to analyse chlorpyrifos and fenitrothion residues in cucumber and tomato samples. The LODs of fenitrothion and chlorpyrifos in the vegetable samples ranged from 0.05 μg g-1 - 0.10 μg g-1, while the LOQs ranged from 0.08 - 0.29 μg g-1. The percentage extraction recoveries (%ER) ranged from 74.8% to 81.5% for chlorpyrifos and from 79.5% to 90.3% for fenitrothion. These were satisfactory %ER values that demonstrated the high efficiency of the DES-modified CF-based MEPS technique. The intra-day %RSDs for the pesticides in the vegetable samples ranged from 1.76% to 8.22%, while the inter-day %RSDs ranged from 7.48% to 9.03%. The developed method, therefore, demonstrated acceptable precision and reproducibility. The greenness of the DES-modified CF–based MEPS procedure was evaluated using ComplexGAPI and AGREE metric tools. The complexGAPI pictogram was dominated by yellow and green colours, with very few sections featuring red, and its overall AGREE score is 0.72. This indicates a high degree of greenness.1 online resource (xx, 272 leaves): color illustrationsenUniversity of VendaUCTD632.95042Pesticides -- Environmental aspectsPesticides residues in foodPesticides -- ToxicologyBotanical pesticidesThesisMusarurwa H. Development of greener preconcentration and extraction techniques using emerging solvents and alternative sorbents for pesticide analysis. []. , 2026 [cited yyyy month dd]. Available from:Musarurwa, H. (2026). <i>Development of greener preconcentration and extraction techniques using emerging solvents and alternative sorbents for pesticide analysis</i>. (). . Retrieved fromMusarurwa, Herbert. <i>"Development of greener preconcentration and extraction techniques using emerging solvents and alternative sorbents for pesticide analysis."</i> ., , 2026.TY - Thesis AU - Musarurwa, Herbert AB - The increase in the human population has placed a serious strain on global food security. In an effort to restore food security, the agricultural sector has increased its use of pesticides to mitigate pest damage to crop yields. As a result, pesticides are widely present in food products and the environment, posing serious health risks. The problem is aggravated by the fact that pesticides can have detrimental effects on living organisms even at trace concentrations. This realization prompted regulatory agencies and food safety authorities to place significant emphasis on developing effective green sample preparation techniques for the enrichment of pesticides prior to instrumental analysis. Thus, various green micro-extraction techniques, such as Dispersive Liquid-Liquid Microextraction (DLLME), Stir Bar Sorptive Extraction (SBSE), Thin Film Microextraction (TFME), and Quick Easy Cheap Effective Rugged Safe (QuEChERS), have been developed. Most of these techniques use organic solvents at microliter levels. Some organic solvents are toxic and persistent in the environment. Consequently, they may enter food chains, where they may undergo bioaccumulation, leading to concentrations exceeding the maximum allowable limits. Thus, the toxicity of organic solvents is a major factor that motivated the development of microextraction techniques that use alternative green solvents in this research. On the other hand, the commercial sorbents used in different formats of solid phase microextraction are prohibitively expensive, and some are not eco-friendly. This puts a deep dent in the greenness of these micro-extraction techniques. The environmental sustainability of microextraction techniques can be enhanced by utilizing green, emerging solvents and sorbents, which is the primary focus of this study. The successive paragraphs summarize the findings of this study. Firstly, a novel medicine dropper-assisted solvent bar micro-extraction (MD-SBME) method was developed, utilizing the meltdown layer of a facemask (MLF) as a solvent holder. A hydrophobic natural deep eutectic solvent (NADES) made from thymol and menthol was used as the extraction solvent during the MD-SBME analysis of imidacloprid pesticide in fruit samples. Under the optimum conditions, detection and quantification limits were in the range of 0.007 – 0.02 μg g-1 and 0.02 – 0.069 μg g-1, respectively. The correlation of determinations (R2) for pineapple, pear, and apple samples were 0.9986, 0.9982, and 0.9973, respectively, and the extraction recoveries ranged from 72 – 110%. Good precision was achieved when the developed method was applied to real sample analysis, with all %RSD values less than 5%. The greenness of the MD-SBME technique was evaluated using the ComplexMoGapi algorithm, yielding a total score of 85. A total score of 65 was obtained when the practicality of the MD-SBME procedure was evaluated using the BAGI metric tool. Thus, the technique has good greenness and practicality profiles. Secondly, a novel chemical mop-based solvent bar micro-extraction (CM-SBME) method was developed, utilizing a polyester dish sponge (PDS) as the solvent holder for extraction. The limits of detection of the pesticides in the milk samples, under optimal conditions, were found to be in the range of 0.014 –0.03 mg L-1. The limits of quantification for the pesticides in the milk samples ranged from 0.045 to 0.096 mg L-1, while percentage extraction recoveries ranged from 72% to 90% for glyphosate and from 72% to 95.6% for fenitrothion. The CM-SBME procedure was evaluated using the Blue Applicability Grade Index (BAGI) and the Analytical Greenness Metric for Sample Preparation (AGREEprep) algorithms to assess practicality and greenness, respectively. Overall scores of 0.71 and 62.5 were obtained for AGREEprep and BAGI, respectively. These were relatively good scores, indicating that the developed CM-SBME procedure had a favorable green profile and practicality. Lastly, deep eutectic solvents (DESs) were utilized in this research to modify cellulose acetate cigarette filters (CFs), which were then employed as adsorbents during microextraction by packed sorbent (MEPS) for chlorpyrifos and fenitrothion in vegetable samples. Under optimum conditions, the developed DES-modified CF–based MEPS method was used to analyse chlorpyrifos and fenitrothion residues in cucumber and tomato samples. The LODs of fenitrothion and chlorpyrifos in the vegetable samples ranged from 0.05 μg g-1 - 0.10 μg g-1, while the LOQs ranged from 0.08 - 0.29 μg g-1. The percentage extraction recoveries (%ER) ranged from 74.8% to 81.5% for chlorpyrifos and from 79.5% to 90.3% for fenitrothion. These were satisfactory %ER values that demonstrated the high efficiency of the DES-modified CF-based MEPS technique. The intra-day %RSDs for the pesticides in the vegetable samples ranged from 1.76% to 8.22%, while the inter-day %RSDs ranged from 7.48% to 9.03%. The developed method, therefore, demonstrated acceptable precision and reproducibility. The greenness of the DES-modified CF–based MEPS procedure was evaluated using ComplexGAPI and AGREE metric tools. The complexGAPI pictogram was dominated by yellow and green colours, with very few sections featuring red, and its overall AGREE score is 0.72. This indicates a high degree of greenness. DA - 2026-05-19 DB - ResearchSpace DP - Univen LK - https://univendspace.univen.ac.za PY - 2026 T1 - Development of greener preconcentration and extraction techniques using emerging solvents and alternative sorbents for pesticide analysis TI - Development of greener preconcentration and extraction techniques using emerging solvents and alternative sorbents for pesticide analysis UR - ER -