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抗凝血灭鼠剂被广泛用于控制共生啮齿动物[1],其中杀鼠醚因其持久性、生物累积性和毒性,近年来引起了国际上多个组织的关注[2-3]. 暴露在水生环境中、饮用被污染的水或食用含有杀鼠醚残留的食物会对人体健康乃至整个生态系统产生不利影响. 目前,杀鼠醚的检测方法主要包括高效液相色谱法[3]、气相色谱法[4]、薄层色谱法[5]、高效液相色谱-质谱法[6]和电喷雾电离串联质谱法[7]. 然而,这些方法都有一定的局限性,对样品纯度有严格的要求,需要繁琐的前处理步骤,对操作人员的技能要求较高[8]. 同时由于仪器体积较大,不适用于现场分析[9]. 因此,迫切需要建立一种杀鼠醚的现场快速检测方法.
表面增强拉曼光谱(surface-enhanced Raman spectroscopy,SERS)可以提供简单、快速和无损的检测,该技术具有高灵敏度和独特的光谱指纹,并且不受水分子的干扰,可以很好地适用于复杂的样品检测分析[10]. 目前,SERS技术已被应用于土壤[1]、水果和蔬菜[11]样品中的常规农药检测,但仍缺乏快速检测抗凝血杀鼠剂的相关报道.
本文建立了一种简单快速的SERS方法,以纳米金作为活性基底,结合便携式拉曼光谱仪,实现了环境水中杀鼠醚的快速现场检测(图1). 与传统方法相比,该方法灵敏度高,检出限低,回收率良好,仅需3 min即可完成整个检测过程,有望成为现场应急分析的有效手段.
基于表面增强拉曼光谱技术的环境水样中杀鼠醚的现场快速检测方法
Rapid on-site detection of coumatetralyl in environmental water based on surface-enhanced Raman spectroscopy
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摘要: 杀鼠醚在水环境中的蓄积可对生态系统造成破坏,并对人体健康产生不利影响. 本文利用表面增强拉曼光谱(SERS)技术,构建环境水中杀鼠醚的简单、快速定性及定量检测分析方法. 采用化学合成法制备了粒径为45—60 nm的纳米金作为SERS活性基底,以便携式拉曼光谱仪作为检测平台,实现了3 min内完成环境水中杀鼠醚的检测. 通过对实验条件进行优化,该方法的检出限低至1.53 ng·mL−1,加标回收率为90.2%—98.2%. 在浓度为0.025—5 μg·mL−1范围内,杀鼠醚浓度与SERS信号强度间呈现出良好的线性关系,R2 = 0.990. 与传统方法相比,该方法操作简单、快速、成本低廉,为水中杀鼠醚的现场检测分析提供了可靠的新选择.Abstract: The accumulation of coumatetralyl (CMTT) in the aquatic environment has caused damage to the ecosystem and adversely affected human health. In this paper, a simple and rapid qualitative and quantitative analysis of CMTT in environmental water was carried out using surface-enhanced Raman spectroscopy (SERS). Gold nanoparticles with a particle size of 45—60 nm were prepared by chemical synthesis method and used as SERS substrate. Combined with a portable Raman spectrometer, the whole detection process could be completed within 3 minutes. By optimizing the experimental conditions, the detection limit of this method was 1.53 ng·mL−1, and the recovery was 90.2%—98.2%. In the range of 0.025—5 μg·mL−1, the response between the concentration of CMTT and SERS signal intensity showed a clear linear dependence, R2 = 0.990. Compared with the traditional method, this method was simple, rapid and low-cost, providing a reliable application scenario for detecting and analyzing CMTT in water.
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图 2 (a)本研究制备的纳米金透射电镜图;(b)纳米金、1 μg·mL−1杀鼠醚混合纳米金的紫外-可见光谱;(c)将1 μg·mL−1杀鼠醚与纳米金混合液加入硝酸镁聚沉后的紫外-可见光谱(插图显示纳米金胶体聚沉前后的颜色变化);(d) (b)和(c)对应溶液的SERS强度
Figure 2. (a) TEM image of Gold nanoparticles (Au NPs) prepared in this study; (b) UV-Vis spectra of colloidal Au NPs, Au NPs mixed with 1 μg·mL−1 CMTT; (c) UV-Vis spectra of aggregated Au NPs after adding 10 μL of 0.5 mol·L−1 Mg(NO3)2 (The inset shows the color change of Au NPs before and after aggregation); (d) SERS intensity of the solutions corresponding to (b) and (c)
图 5 加入0.1 mol·L−1(a)、0.25 mol·L−1(b)、0.5 mol·L−1(c)、1 mol·L−1(d)硝酸镁聚沉后纳米金的TEM图像;(e) 加入不同浓度硝酸镁聚沉纳米金的紫外-可见光谱;(f)不同浓度的硝酸镁对995 cm−1处的SERS强度影响
Figure 5. TEM image of Au NPs after adding 0.1 mol·L−1 (a), 0.25 mol·L−1 (b), 0.5 mol·L−1 (c) and 1 mol·L−1 (d) Mg(NO3)2; (e) UV-Vis spectra of Au NPs with different concentrations of Mg(NO3)2; (f) SERS intensity at 995 cm−1 induced by different concentrations of Mg(NO3)2
图 7 (a)不同浓度杀鼠醚溶液的SERS检测;(b)杀鼠醚SERS峰强度随浓度变化的曲线;(c)水样中不同浓度杀鼠醚的SERS检测;(d)水样中杀鼠醚SERS峰强度随浓度变化的曲线
Figure 7. (a) SERS detection of CMTT aqueous solution with different concentrations; Calibration curve for different CMTT; (c) SERS detection of CMTT with different concentrations in water samples; Calibration curve for different CMTT in water samples
图 8 使用同批次纳米金在21 d内测定(a)1 μg·mL−1和(b)0.05 μg·mL−1杀鼠醚在995 cm−1处的SERS强度;(c)8个不同批次纳米金检测加标水样中0.25 μg·mL−1杀鼠醚在995 cm−1处的SERS强度;(d)同批次纳米金检测加标水样中0.25 μg·mL−1杀鼠醚在995 cm−1处的SERS强度
Figure 8. SERS intensity at 995 cm−1 of (a) 1 and (b) 0.05 μg·mL−1 CMTT acquired over 21 d using the same batch of Au NPs; (c) SERS intensity at 995 cm−1 of 0.25 μg·mL−1 CMTT in spiked water using eight batches of Au NPs; (d) SERS intensity at 995 cm−1 of 0.25 μg·mL−1 CMTT in spiked water generated by the same batch of Au NPs
表 1 环境水中不同浓度杀鼠醚的平均回收率
Table 1. Average recoveries of different CMTT concentrations in spiked environmental water
加标量/(μg·mL−1)
Added回收量±标准差/(μg·mL−1)
Found ± SD回收率/%
Recovery相对标准偏差/%
RSD0.50 0.48 ± 0.12 96.4 6.40 1.00 0.90 ± 0.12 90.2 2.86 2.50 2.46 ± 0.36 98.2 2.69 表 2 各农药对应SERS谱带的分配
Table 2. The Assignation of SERS spectral bands corresponding to each pesticide
表面增强拉曼光谱位移/cm−1
SERS shift归属结构
Assignation563 C—C—C弯曲振动 939 C—O/C—H弯曲振动 1028 C—O弯曲振动/C—C拉伸振动 1044 C—O弯曲振动/C—C拉伸振动 1145 H—C—H弯曲振动/CH2扭转 1193 C—H平面弯曲 1323 H—C—H/CH3/CH2/CH弯曲振动 1379 H—C—H/CH2扭转 -
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