First Name:
Alexis
Last Name:
Dale
Major Department:
Chemistry
Thesis Director:
Carol Babyak
Date of Thesis:
May 2012
In North Carolina, the cultivation of Fraser firs is a large industry which harvests over 3,000,000 trees per year1. Commonly used pesticides include dimethoate, disulfoton (di-syston 15 G), lindane, and simazine2. The development of a method to quantify these pesticides in local surface waters using polar organic chemical integrative sampling (POCIS) devices is described. An OASIS HLB (hydrophilic-lipophilic balance) available from Waters was used as the sorbent material in the POCIS device. An appropriate solvent is used to elute the pesticide from the sorbent material, and gas chromatography-mass spectrometry (GC-MS) is used to analyze the extracts. The GC-MS temperature program was optimized with an Agilent HP-5MS column which allowed for baseline resolution of the four pesticides. Calibration curves were linear from 10-200 ppm and R2values greater than 0.99 were generally obtained for the four pesticides. The GC-MS method detection limits (MDLs) were 1.80, 2.28, 3.08, and 6.51 ppm for dimethoate, disulfoton, lindane, and simazine, respectively. The solvent used to elute the pesticides from the sorbent was explored by conducting solid phase extraction (SPE) experiments, but has not yet been fully optimized. A preliminary calibration study of the POCIS device was performed to determine the sample uptake rate of the sorbent material. The POCIS device was exposed to pesticide-spiked water in a 4-day and 7-day experiment. Based on this very preliminary study, non-linear uptake was observed for simazine, lindane, and dimethoate; disulfoton was not adsorbed by the sorbent in either experiment. Future work includes further SPE experiments to optimize the elution sorbent, calibration experiments to determine the sample uptake rate, and deployment of these devices in streams thought to be impacted by Fraser fir tree farms.