Abstract A sensitive colorimetric assay is reported for carbamate pesticide detection. The detection strategy was based on carbamate hydrolyzed product induced aggregation of l-cysteine-modified gold nanoparticles (Cys-AuNPs) in the presence of pH 5.8 phosphate buffer and sodium chloride. Sodium chloride was added to increase the speed of aggregation (pre-aggregation) to make the modified gold particles less stable. Carbamate pesticides are easily hydrolyzed at room temperature in the presence of sodium hydroxide. Their hydrolyzed products contain constituents that can easily reduce the Cys-AuNP aggregation, with concomitant color perturbation from ruby red to purple and blue-gray in 10 min. The linear range of the determination of carbaryl and methomyl was from 14.0 to 71.0 µg/mL and 7.0 to 36.0 µg/mL, respectively, with limits of detection of 7.15 µg/mL for carbaryl and 3.49 µg/mL for methomyl. The assay’s practicality was demonstrated by the determination of chili samples with satisfactory recovery (87–91%) and precision (relative standard deviations less than 3.5%). Thus, the assay is a promising screening tool of pesticide residues in chili with high selectivity.

中文翻译：

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L-半胱氨酸修饰金纳米颗粒的水解产物介导聚集作为辣椒中氨基甲酸酯残留的比色探针

摘要 报道了一种用于氨基甲酸酯类农药检测的灵敏比色法。检测策略基于氨基甲酸酯水解产物诱导的 l-半胱氨酸修饰金纳米粒子 (Cys-AuNPs) 在 pH 5.8 磷酸盐缓冲液和氯化钠存在下的聚集。添加氯化钠以增加聚集（预聚集）的速度，从而使改性金颗粒不太稳定。氨基甲酸酯类农药在室温下在氢氧化钠存在下很容易水解。他们的水解产物含有可以轻松减少 Cys-AuNP 聚集的成分，伴随颜色扰动在 10 分钟内从红宝石色变为紫色和蓝灰色。甲萘威和灭多威的线性范围分别为 14.0 至 71.0 µg/mL 和 7.0 至 36.0 µg/mL，检出限为 7。甲萘威为 15 µg/mL，灭多威为 3.49 µg/mL。通过测定具有令人满意的回收率 (87–91%) 和精密度（相对标准偏差小于 3.5%）的辣椒样品，证明了该测定的实用性。因此，该测定法是一种具有高选择性的辣椒中农药残留筛查工具。