This study developed a simple, efficient and environmentally friendly fabrication method for surface-enhanced Raman spectroscopy (SERS) wipers for the rapid detection of individual and mixed pesticide residues in real samples. Non-toxic NaCl was used to overcome the electrostatic repulsion between cotton swabs and AgNPs in the decorating process. Cotton swabs containing NaCl molecules were immersed in a silver colloid to synthesize a silver-decorated cotton swab (SERS wiper). The fabrication conditions were optimized to improve the performance of the SERS wiper. Under optimal conditions, AgNPs were evenly and densely distributed on cotton swabs within 10 min of the synthesis process. Raman reporter molecules (Rhodamine 6G) were tested and good results were obtained: sensitivity was 2 × 10⁻⁹ M, RSDs were within 7.5%, showing good reproducibility and uniformity, and the storage life reached 32 days. Thiabendazole (TBZ), thiram, and their mixture in bitter gourds were successfully detected using the “wipe sampling-detection” method coupled with the SERS wipers. The detection limits of TBZ and thiram were 1 ng cm⁻². Multiple linear regression (MLR) and leave-one-out cross-validation methods were employed for quantitative analysis. The linear correlation coefficients of the predicted results and reference concentrations of individual and mixed pesticide residues in bitter gourds were all above 0.99, and the RMSEs were within 7 ng cm⁻². These results indicate that the SERS wipers combined with MLR models could accurately and quantitatively detect individual and mixed pesticide residues in real samples.

中文翻译：

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制备用于SERS定量检测苦瓜中混合农药残留的敏感银装饰棉签

这项研究开发了一种简单，有效且环保的表面增强拉曼光谱（SERS）刮水器制造方法，用于快速检测真实样品中的单个和混合农药残留。在装饰过程中，使用无毒的NaCl克服了棉签和AgNP之间的静电排斥。将包含NaCl分子的棉签浸入银胶体中，以合成装饰有银的棉签（SERS擦拭器）。优化了制造条件以提高SERS刮水器的性能。在最佳条件下，在合成过程的10分钟内，AgNPs均匀且密集地分布在棉签上。测试了拉曼报告分子（若丹明6G），并获得了良好的结果：灵敏度为2×10 ^-9M，RSD在7.5％以内，显示出良好的重现性和均匀性，并且存储寿命达到32天。噻苯达唑（TBZ），噻菌灵及其在苦瓜中的混合物已通过“擦拭取样-检测”方法与SERS刮水器一起成功检测出。TBZ和锡拉姆的检出限为1 ng cm ^-2。多元线性回归（MLR）和留一法交叉验证方法用于定量分析。苦瓜中单个农药和混合农药残留的预测结果与参考浓度的线性相关系数均在0.99以上，RMSE均在7 ng cm ^-2以内。这些结果表明，SERS刮水器与MLR模型结合使用可以准确，定量地检测实际样品中的单个和混合农药残留。