Development of a solid phase extraction-gas chromatography method for the determination of endocrine disrupting pesticides in water from water treatment plants
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Date
2018
Authors
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Publisher
University of Namibia
Abstract
A solid phase extraction (SPE) method for the gas chromatography analysis of pesticides was developed, optimised and validated for the simultaneous determination of pesticides from the Gammams water treatment plant (GWTP) and the Unique Janitorial & Maintenance Services (UJAMS) wastewater treatment plant (UWWTP). Parameters including, sample volume, elution solvent and ionic strength were optimised to improve the performance of the SPE method. After optimisation, the method gave good sensitivity with a detection limit ranging from 0.0009-0.0270 μg/mL, a good repeatability with a relative standard deviation ≤13 % and acceptable recoveries of 76 % and above. For most of the pesticides the method was linear in the range of 0.00625-0.15 μg/mL with R2 values ranging from 0.9800-1.000, except for atrazine (6) and δ-HCH (7) where the R2 values were 0.9558 and 0.9608, respectively. The validated method was subsequently applied to the determination of pesticides in water from the selected water treatment plants. Five herbicides namely, prometon (5), atrazine (6), alachlor (9), metolachlor (11) and butachlor (14) were detected in water samples from the GWTP inlet sampling point. Alachlor (9) and metolachlor (11) were present in the highest concentrations at 0.1858 and 0.2301 μg/mL, respectively. Prometon (5) and butachlor (14) were found to be present at concentrations of 0.0460 and 0.0100 μg/mL, respectively, while atrazine (6) was present at the lowest concentration of 0.0040 μg/mL. No pesticides were detected in water samples from the UWWTP, which could be attributed to the fact that the inflow of wastewater to this plant is strictly from industrial activities.
Description
A mini thesis submitted in partial fulfillment of the requirements for the Degree of Master of Science
Keywords
Pesticides, SPE, GC-FID