Herbicide use, mainly glyphosate, has been intense in worldwide agriculture, including in the Brazilian Amazon region. This study aimed to validate a method for determining glyphosate and its degradation product, AMPA, and glufosinate by HPLC-FL in 58 water samples collected at the Santarém plateau region (Planalto Santareno), in the western of Pará state, Brazil. The method involves filtration and direct injection in the HPLC-FL for AMPA analysis, or previous concentration (10×) by lyophilization for glufosinate and glyphosate analysis. Analytes were oxidized and complexed with o-phthalaldehyde and 2-mercaptoethanol in a post-column reaction before fluorescence detection. LOQs for AMPA, glyphosate and glufosinate were established at 0.5, 0.2 and 0.3 μg L⁻¹, respectively. A total of 58 samples were collected. Glyphosate and glufosinate were not detected in any of the 30 surface water samples collected in 2015 (<LOQ), and AMPA was detected in 6 samples (0.65–1.93 μg L⁻¹). A total of 28 ground and surface water samples were collected in 2017 and analyzed for glyphosate, which was detected in 11 samples (7 ground water samples), with concentrations between 1.5 and 9.7 μg L⁻¹. A continuous pesticide monitoring of the Amazonian water system is essential to guarantee the preservation of this important ecosystem.

除草剂（主要是草甘膦）在全球农业中的使用非常频繁，包括巴西亚马逊地区。本研究旨在验证一种通过 HPLC-FL 测定巴西帕拉州西部圣塔伦高原地区 ( Planalto Santareno ) 的 58 个水样中草甘膦及其降解产物 AMPA 和草铵膦的方法。该方法涉及过滤并直接注射到 HPLC-FL 中进行 AMPA 分析，或通过冻干进行预先浓缩 (10×) 进行草铵膦和草甘膦分析。在荧光检测之前，分析物在柱后反应中被氧化并与邻苯二甲醛和 2-巯基乙醇络合。 AMPA、草甘膦和草铵膦的 LOQ 分别确定为 0.5、0.2 和 0.3 μg L ^-1 。共采集58个样本。 2015年采集的30个地表水样品中均未检出草甘膦和草铵膦（ −1)。 2017年共采集了28个地下水和地表水样品并进行了草甘膦分析，其中11个样品（7个地下水样品）中检出草甘膦，浓度在1.5至9.7 μg L ^-1之间。对亚马逊水系统进行持续农药监测对于保证这一重要生态系统的保护至关重要。