Abstract
The intensive use of pesticides in agriculture has prompted researchers to develop new methods for identifying these pollutants in water. This study sought to validate a high performance liquid chromatography (HPLC) method to determine the concentration of the pesticide glyphosate in groundwater samples by using solid-phase extraction (SPE) filters after derivatization with chloroformate 9-fluorenylmethoxycarbonyl (FMOC-Cl). For the HPLC method, we evaluated the following main validation parameters: linearity, specificity, precision, accuracy, robustness, and limits of detection and quantification. After validation of the method, we determined the concentration of glyphosate in samples from thirteen deep, tubular wells distributed in urban and rural areas in Chapeco, SC, Brazil. The solvent used in the extraction of excess FMOC-Cl was dichloromethane and subsequently filtration was performed on C18 SPE, and injected into the chromatograph column in amino polymer with fluorescence detection. The analytical curve made in ultrapure water was linear, with a correlation coefficient of 0.99. The limits of detection and quantification were 0.24 and 0.07 µg L-1, respectively. Recovery tests in natural waters ranged from 90.37 to 101.70%. Glyphosate was detected in 5 of the thirteen wells evaluated. The highest concentration of glyphosate (6.80 µg L-1) was detected in a countryside well, near the municipal water supply. Despite the low levels of glyphosate detected in our study, any amount present in groundwater samples is worrisome, as these molecules have low ground mobility.
Highlights
In 2012, herbicides were the second largest group of pesticides sold globally (Sindiveg, 2012)
In (c) the glyphosate peak becomes partially covered by FMOC-Cl reagent around 3 minutes
Specificity and selectivity The method used to specificity and selectivity of the analysis was specific and selective for glyphosate through comparative analysis of chromatogram with the standard and with a sample analysis without glyphosate; we did not observe any interference in the analyses
Summary
In 2012, herbicides were the second largest group of pesticides sold globally (Sindiveg, 2012). The primary and most popularly used is glyphosate [N-(phosphonomethyl) glycine], C3H8NO5P. This powerful agrochemical is used to kill weeds that harm agricultural production, and its deleterious effects on the environment are evident in both aquatic and terrestrial ecosystems, as well as in humans (Amarante Jr. et al, 2002; Pinheiro et al, 2011). High solubility in water (12.000 mg L-1) assists in the transport of glyphosate from terrestrial to aquatic environments. These molecules can be transported to both surface and groundwater, groundwater samples have not been extensively investigated by the scientific community (Sanchís et al, 2011)
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