Detection of pesticide residues on apples using surface-enhanced Raman spectroscopy
2014-06
Loading...
View/Download File
Persistent link to this item
Statistics
View StatisticsJournal Title
Journal ISSN
Volume Title
Title
Detection of pesticide residues on apples using surface-enhanced Raman spectroscopy
Authors
Published Date
2014-06
Publisher
Type
Thesis or Dissertation
Abstract
Pesticides are an integral part of agriculture, while increasing use leads to residues in/on agricultural products. Federal monitoring and enforcement action is dependent on the technical capability to detect pesticides. However, current methods are elaborate, time-consuming and not cost-effective. In the first part of this work, a rapid and simple surface-enhanced Raman spectroscopy (SERS) method coupled with a surface swab method for recovery and quantitative detection of thiabendazole (TBZ) on apple surfaces was developed, optimized and validated. The whole apple surface was swabbed and the swab was vortexed to release the pesticides. After that, silver dendrites (AgD) were used to bind the pesticide for Raman measurement. The limit of detection of TBZ in methanol was 0.01µg/mL, (10ppb), while the Environmental Protection Agency (EPA) limit is 5µg/gram apple-weight (5 ppm). The concentration of the recovered TBZ was predicted using a partial least square model. The recovery from the surface swab method was calculated to be 59.7% to 76.6% for intentional contamination at 0.1, 0.3, 3 and 5 ppm (µg/g apple-weight) level, respectively. The final accuracy of the swab-SERS method was calculated to be between 90.0% and 115.4%, after corrected by the releasing factor (66.6%). In the second part, a new approach was proposed to detect acetamiprid using an aptamer-based SERS method. The acetamiprid aptamer was chosen from the literature, thoilated and conjugated onto AgD. To block the unbounded surface on the substrate surface after aptamer immobilization, bovine serum albumin (BSA), 2-mercaptoethanol (ME) 6-mercaptohexanol (MCH) and were investigated as blocking agents. MCH and ME cannot fully block the surface when encountered with interference. The typical peaks from acetamiprid did not show on the aptamer-blocking agent-acetampired spectra when using BSA as blocking agents. The aptamer and blocking agent immobility on AgD should be further investigated and the method should be further modified. Last, the swab method was further developed and validated using UV-visible spectroscopy as a reference method. A standard curve was established based on the absorbance at 245 nm at different concentrations from 0 ppm to 1000 ppm. The assay standard curve well fit the five-parameter logistic model (r2 =0.995). The concentration of acetamiprid in the extracts was determined using this standard curve. The recovery rate of refined surface swab method is 90.6 % ± 1.4 % (n=5). This assay has a low intra- and inter-assay coefficient of variation (CV < 5 %).
Description
University of Minnesota M.S. thesis. June 2014. Major: Food Science. Advisor: Dr. Theodore P. Labuza. 1 computer file (PDF); x, 94 pages, appendices A-F.
Related to
Replaces
License
Series/Report Number
Funding information
Isbn identifier
Doi identifier
Previously Published Citation
Suggested citation
Chen, Tuo. (2014). Detection of pesticide residues on apples using surface-enhanced Raman spectroscopy. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/165428.
Content distributed via the University Digital Conservancy may be subject to additional license and use restrictions applied by the depositor. By using these files, users agree to the Terms of Use. Materials in the UDC may contain content that is disturbing and/or harmful. For more information, please see our statement on harmful content in digital repositories.