基于免疫传感器和激光诱导击穿光谱的痕量农药测量方法

农药在农作物病虫害及农作物高产稳产等方面起到了相当重要的作用，但是农药的长期大量使用，对生态和人类健康造成了极大的危害。根据相关文献查阅，基于免疫传感器和激光诱导击穿光谱的分析方法对农药残留的检测未见相关报道。提出了激光诱导击穿光谱对免疫传感器捕获待测目标物的探针进行检测，从而间接计算出待测目标物的浓度。使用免疫层析试纸条对痕量农药进行检测，虽然免疫层析试纸条可以实现对痕量农药的测量，但是仅能定性且检测的范围很窄，为了拓宽免疫层析试纸条对痕量农药的测量范围，运用激光诱导击穿光谱（laser induced breakdown spectroscopy，LIBS）对免疫层析试纸条上捕获痕量农药的金属纳米颗粒进行光谱测量，构建免疫层析试纸条与LIBS的检测方法。以毒死蜱农药为研究对象，因农药残留属于小分子抗原检测，所以免疫层析试纸条运用竞争法对毒死蜱进行检测。滴加了低浓度毒死蜱的免疫层析试纸条上控制线和检测线的颜色差异不明显，难以用人眼分辨出是否检测到了毒死蜱。对添加了毒死蜱的免疫层析试纸条的控制线和检测线分别选取点，测量Au Ⅰ 242.733 nm处的光谱，用控制线的平均光谱强度减去检测线的平均光谱强度即为毒死蜱的信号，此方法可以检测出免疫层析试纸条观察不到的信号，还规避了LIBS检测限高的问题。随着毒死蜱浓度从0增加到106 ng·mL-1，LIBS光谱数据差值逐渐增大。为了消除随机误差的影响，使用ΔLIBS强度（测量样品强度减去空白样品强度）与毒死蜱浓度取Lg绘制校准曲线。ΔLIBS强度与毒死蜱浓度在10～106 ng·mL-1范围内呈线性相关，Y=6.14X+31.85，R2=0.969，毒死蜱的检测限为0.39 ng·mL-1。研究表明，免疫层析试纸条与LIBS结合实现了对痕量农药的测量，能有效的扩宽毒死蜱的检测范围。同时，免疫层析试纸条与LIBS的结合对其他物质的检测也值得进一步研究。

Trace Pesticide Measurement Method Based on Immunosensor and Laser-Induced Breakdown Spectroscopy

Pesticides have played a significant role in crop diseases and insect pests, as well as high and stable yields of crops, but the long-term large-scale use of pesticides has caused great harm to ecology and human health. According to the relevant literature review, there are no related reports on the detection of pesticide residues based on the analysis methods of immunosensors and laser-induced breakdown spectroscopy. In this method, a laser-induced breakdown spectrum is proposed to detect the probe of the immunosensor capturing the target to be detected, there by indirectly calculating the concentration of the target to be measured. This article uses immunochromatographic test strips to detect trace pesticides. Although immunochromatographic test strips can measure trace pesticides, they can only be qualitative, and the detection range is narrow. In order to broaden the measurement range of trace pesticides by immunochromatographic test strips, laser-induced breakdown spectroscopy (Laser-induced Breakdown Spectroscopy, LIBS) was used to perform spectroscopic measurements on metal nanoparticles captured trace pesticides on immunochromatographic test strips. Construction of detection methods for immunochromatographic test strips and LIBS. In this paper, chlorpyrifos pesticides are used as the research object. Because pesticide residues are small molecule antigen detection, the immunochromatographic test strips use the competition method to detect chlorpyrifos. The color difference between the control line and the detection line of the immunochromatographic test strip with a low concentration of chlorpyrifos dripped is not obvious, and human eyes cannot distinguish whether chlorpyrifos is detected. The control line and detection line of the immunochromatographic test strip added with chlorpyrifos were selected respectively, and the spectrum at Au Ⅰ 242.733 nm was measured. The average spectral intensity of the control line minus the average spectral intensity of the detection line is the signal of chlorpyrifos. This method can detect signals not observed by immunochromatographic test strips, and avoid the problem of high detection limit of LIBS. As the chlorpyrifos concentration increased from 0 to 106 ng·mL-1, the difference in LIBS spectral data gradually increased. In order to eliminate the effect of random errors, a calibration curve was constructed using ΔLIBS intensity (measurement sample intensity minus blank sample intensity) and chlorpyrifos concentration to obtain Lg. ΔLIBS intensity was linearly correlated with chlorpyrifos concentration in the range of 10～106 ng·mL-1, Y=6.14X+31.85, R2=0.969, and the detection limit of chlorpyrifos was 0.39 ng·mL-1. The results showed that the immunochromatographic strip combined with LIBS could effectively expand the detection range of chlorpyrifos. At the same time, the combination of immunochromatographic test strips and LIBS for the detection of other substances is also worthy of further research.