Research On Water Pollutants Detection Method Based On LIBS And Immunochromatographic Test Strip

Pesticide residues and pathogens are important micro pollution sources in water environment,which threaten human health through water circulation and food chain transmission.Laser-Induced Breakdown Spectroscopy(LIBS)technology has the advantages of simultaneous detection of multiple elements and sensitive detection.However,because LIBS can only analyze the elements of a substance,it cannot directly measure molecules and bacteria,which limits the application prospects of LIBS.To solve this problem,this study used antibody-conjugated metal nanoparticles as beacon probes to achieve specific capture of water pollutants(pesticide residues and bacteria)on immunochromatographic test strips,and LIBS The measurement of metal nanoparticles indirectly realizes the quantitative analysis of the test object.This paper analyzes the factors affecting the measurement of pesticide residues and bacteria by LIBS,including the presence or absence of Ar environment,laser energy,laser spot size,and delay time.The best experimental conditions for quantitative analysis are the Ar-free environment,laser energy of 200 m J,laser spot of 75?m,and delay time of 0?s.Gold nanoparticles(Au NPs),which are commonly used in immunochromatography,are used as the beacon probe of chlorpyrifos,quantitative analysis of Au using external standard method.The calibration curve of Au I 242.733 nm is obtained,the detection limit of chlorpyrifos is 0.39 ng/m L and R~2 is 0.969.Further,taking Staphylococcus aureus as an example,the detection method of bacteria in water-based on LIBS and Immunochromatography strip was studied,and the beacon probes were selected.Comprehensively considering the visualization of immunochromatographic test strips and the intensity of the spectral signal,alloy nanoparticles(Ag3Au2BNPs)with a silver-to-gold mass ratio of 3:2 were selected as beacon probes to study Staphylococcus aureus in drinking water.Stability analysis of immunochromatographic test strips was carried out under the best experimental conditions,and the relative standard deviation of test strip between batches can be controlled within 3.16%,which ensures the good repeatability of the test strip measurement.At the same time,a quantitative analysis of the Staphylococcus aureus samples was performed,and a calibration curve of Ag I 328.044 nm was obtained.The detection limit of Staphylococcus aureus is calculated to be 1.6 CFU/m L and R~2 to be0.991.The detection limit obtained by the traditional colorimetric method is 10~4 CFU/m L,and the detection ability of the LIBS spectroscopy method is improved by about 10~4 times compared with the colorimetric method.The results of this study provide a basis for the highly sensitive detection of water pollutants(pesticide residues and bacteria)based on LIBS and immunochromatographic test strips.