Novel Carbon Nanomaterials-based Mass Spectrometry Probes For High-throughput Screening And Identification Of Chemical Contaminants

Mass spectrometry techniques for high-throughput analysis of complex samples are of profound importance in many areas such as food safety,omics studies,and environmental health science.Nanomaterials have been applied in multiple aspects,such as electrochemical analysis,optical detection,catalytic,adsorption and purification,and electronic devices,due to their size effect,large specific surface area,excellent photoelectric ability and strong optical obsorption.Nanomaterials as mass spectrometry probes can not only used as extractors to enrich target analytes due to their excellent adsorption ability,but also can be used as matrices for desorption and ionization of target analytes based on their excellent optical absorption and energy transfer capacity.Especially for carbon nanomaterials,their capacity of the optical absorption and energy transfer is more prominent.However,when nanomaterials were used in analysis of real complex samples,they often sufferred from their aggregation,poor anti-matrix interference ability,and strong background noise.Therefore,the development of new carbon-based mass spectrometry nanoprobes is of strategic significance for high throughput analysis,detection of complex samples,and environmental health studies.This paper explored three new types of carbon nanomaterials as mass spectrometry probes for high-throughput screening and identification of environmental contaminants in complex samples.The main contents are listed as follows:1.We report ordered mesoporous carbon as a new SELDI probe for rapid screening and identification of trace amount of toxic chemicals in a single drop of human whole blood without complicated sample preparation procedures.We demonstrate that ordered mesoporous carbon not only can selectively enrich a wide variety of low-mass toxic compounds from whole blood samples but also can be used as an excellent matrix to assist the laser desorption/ionization process of small molecules with low background noise,high repeatability,and good salt tolerance.High sensitivity(detection limits at ppt levels)and good reproducibility for typical toxic compounds were obtained.With CMK-8 as a SELDI probe,we successfully identified and screened six perfluorinated compounds in a single drop of whole blood collected from workers in a perfluorochemical plant.The method was also validated with complex samples such as human urine and environmental water samples.With distinct advantages such as simplicity,rapidness,minimal sample requirement,and high reliability,this method keeps great promise for various aspects of application.2.We report the use of fluorographene(FG)as a new mass spectrometry probe for highthroughput identification and screening of emerging chemical contaminants in complex samples.FG was facilely synthesized by one-step exfoliation of fluorographite.With FG as a matrix or probe in matrix-assisted or surfaceenhanced laser desorption/ionization time-of-flight mass spectrometry(MALDI-or SELDI-TOF MS),higher sensitivity(detection limits at ppt or subppt levels),and better reproducibility were achieved than with other graphene-based materials due to the unique chemical structure and selfassembly properties of FG.The method was validated with different types of real complex samples.By using FG as a SELDI probe,we could easily detect trace amount of bisphenol S in paper products and high-fat canned food samples.Furthermore,we have successfully identified and screened as many as 28 quaternary ammonium halides in sewage sludge samples collected from municipal wastewater treatment plants.These results demonstrate that FG probe is a powerful tool for high-throughput analysis of complex samples by MS.3.As an important class of emerging chemical contaminants,short-chain chlorinated paraffins(SCCPs)are considered as one of the most challenging groups of compounds to analyze and quantify.Therefore,we report a new method for fast and high-throughput screening of SCCPs in complex samples based on MALDI-TOF MS with graphene as a matrix and 2,5,6,9-tetrachlorodecane as an internal standard.We found that the use of graphene as MALDI matrix generated high peak intensities for SCCPs while producing few background noises.The ion fragmentation mechanisms of SCCPs in MALDI are discussed in detail.Under the optimized conditions,the detection limits for SCCP congeners were in the range of 0.1-0.9 ng/mL,much lower than those reported previously.Other distinct advantages over other methods,such as short analysis time(<30 s)and free of complicated sample preparation procedures,are also demonstrated.The method was successfully applied in fast screening of SCCPs in indoor dust samples and high-throughput monitoring of human exposure levels to SCCPs,and the results were verified by gas chromatography coupled to negative chemical ionization quadrupole time-of-flight high-resolution mass spectrometry.This work not only offers a simple,fast,high-throughput,and sensitive method for screening of SCCPs,but also further demonstrates the promise of graphene-based matrix in MALDI by using such a complex group of compounds.