Danyun Zhu

Date of Award


Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)


Food Science and Human Nutrition


Rodney J. Bushway

Second Committee Member

L. Brian Perkins

Third Committee Member

Alfred A. Bushway


A simple. relatively fast, and efficient method has been developed for the simultaneous detection of residual levels of the pesticides dithiopyr, fenoxaprop-1'-e~hyl, l~alofenozide, and oryzalin in surface and ground water. This method involves solid phase (SPE) extraction/clean-up of these pesticides from water, followed by detcction and quantification by a high performance liquid chromatograph (HPLC) equipped with a photo diode array detector (DAD). The recoveries for dithiopyr, fenoxaprop-l'-c~I~yl. halofenozide, and oryzalin were performed by fortifying ground water from 0.1 ppb to 100 ppb, and surface water from 0.2 ppb to 100 ppb. For ground water, percent recoveries ranged from 89 to 122 with an average percent coefficient of variation (%CV) of 8.1 for dithiopyr, 82 to 94 with an average %CV of 6.6 for fenoxaprop-P-ethyl. 98 to 1 1 5 with an average %CV of 6.9 for halofenozide. and 95 to 1 1 0 with an average '%CV of 5.7 for oryzalin. For surface water, percent recoveries ranged from 82 to 93 \\:it11 an average %CV of 5.5 for dithiopyr, 78 to 98 with an average %CV of 4.8 for fenoxaprop- P-ethyl, 91 to 102 with an average %CV of 3.2 for halofenozide, and 91 to 100 with an average %CV of 5.6 for oryzalin. The limit of quantitation for dithiopyr, fenoxaprop-P- ethyl, halofenozide, and oryzalin were 0.50 ppb, 0.15 ppb, 0.1 0 ppb, and 0.10 ppb for ground water; 0.50 ppb, 0.30 ppb, 0.20 ppb. and 0.20 ppb for surface ~vater. Reproducibility studies showed that for ground water, %CVs ranged from 2.6 to 25 for dithiopyr, 2.5 to 24 for fenoxaprop-P-ethyl, 1.0 to 9.3 for halofenozide, and 2.0 to 14 for oryzalin. For surface water, the %CVs ranged from 2.2 to 17 for dithopyr, 2.3 to 12 for fenoxaprop-P-ethyl, 0.80 to 9.9 for halofenozide, and 3.9 to 12 for oryzalin.

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