Award Date


Degree Type


Degree Name

Master of Science (MS)



First Committee Member

Kim R. Rogers

Number of Pages



Phosphotriesterase catalyzes the hydrolysis of a wide range of organophosphate insecticides such as paraoxon and parathion and nerve toxins such as soman and sarin. This project resulted in the development of novel phosphotriesterase enzyme assays to measure paraoxon and other representatives of the organophosphate pesticides. The assay is based on a substrate-dependent change in pH at the local vicinity of the enzyme. This enzyme, which was labeled with fluorescein isothiocyanate (FITC), was immobilized on polymethylmethacrylate beads and the pH change is monitored through the pH-sensitive quantum yield of FITC. Analytes were measured using a KinExA fluorescence analyzer. This assay can detect paraoxon concentration down to 11 {dollar}\mu{dollar}M with a dynamic range of 11 {dollar}\mu{dollar}M to 600 {dollar}\mu{dollar}M. In addition to the paraoxon, this assay was also used to measure 9 other insecticides and to determine the concentrations of coumaphos in the biofilter treated cattle dip waste samples.


Assay; Determination; Development; Enzyme; Organophosphate; Pesticides; Phosphotriesterase

Controlled Subject

Environmental sciences; Chemistry, Analytic; Agricultural chemistry

File Format


File Size

2222.08 KB

Degree Grantor

University of Nevada, Las Vegas


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