The Simultaneity Of Silver Nanowires Membrane Dipsticks And Surface Enhanced Raman Spectroscopy For Rapid In-situ Detection

The evaluation of the available fraction of environmental pollutant is extremely important for assessing their risk to the environment and human health.This available fraction,which can be solubilized and/or easily extracted,is believed to be the most accessible for bioaccumulation,biosorption and/or transformation by organisms.The rapid analysis of the available fraction for environmental pollutants can be applied to the initial screening of toxic substances in a short period of time to achieve efficient monitoring process.The separation,purification and enrichment process before the detection have great influence on the subsequent detection,which makes it necessary to develop a convenient and time-saving sample pretreatment method.The noble metal substrate can be chemically bonded to the functional groups such as thiol or amino groups,and this substrate can be adsorbed directly to complete the separation and enrichment of sulfur and nitrogen substances.The noble metal substrate can be also modified by self-assembled layer through chemical bond,such as gold,silver and copper can be modified with thiols.The alkyl chains of thiols are oriented,hence yield a hydrophobic regions and change the surface of substance from hydrophilic to hydrophobic.Such hydrophobic substrates can be used to adsorb hydrophobic organics by van der Waals interactions,realizing a sample pretreatment.Surface enhanced Raman spectroscopy(SERS)has been developed on the basis of Raman spectroscopy.It can be used to detect the Raman properties of the adsorbed molecules on the surface of rough metal.SERS is often based on the rough Ag,Cu or Au metal surface,and a variety of new substrate system have been developed.The structure and morphology of the enhanced Raman substrate have a direct influence on the detection sensitivity,and the preparation of SERS substrate which can be used in actual detection is very important.The portable Raman spectrometer can be combined with a variety of sample pretreatment methods,so as to form a rapid and efficient detection system for environmental or medical monitoring.In this dissertation,the silver nanowires membrane loaded on the filter paper was used as the SERS substrate,the main contents can be summarized as follows:(1)The silver nano wire membrane applied as SERS substrate combined with sample pretreatment.When the sulfadiazine molecules come into contact with silver rianowire membrane,the amino of sulfonamide interacted with silver nanowires,so that it can be adsorbed and enrichment on silver membrane,producing the SERS signal when scanned by a portable Raman spectrometer.We used this substrate to detect 4 kinds of sulfonamides,which were proved by qualitative and quantitative analysis.At the same time,the silver nanowires membrane can be used repeatedly to ensure the practicability and economy of the substrate.The method of sample enrichment combined with SERS can reduce the complexity of sample pretreatment steps and shorten the analysis time,creating an in-situ rapid detection for sulfonamides.(2)We report the use of hydrophobic 1-propanethiol modified silver nanowire membrane(PTH-Ag NMs)coupled with portable SERS spectrometer for flexible in-situ swabbing extraction and detection of PAHs.The PTH was modified on the silver nanowire membrane through the covalent bonding between sulphur and silver atom,in order to obtain a hydrophobic membrane structure.The swabbing process with extraction agent was similar to the contact between baby's mouth and toys.Thus present a simulation of migration about PAHs.The influence of chain length and concentration for the modified thiols on hydrophobicity was investigated,and the mechanism of thiol modification on silver nanowire membrane was explained.Several typical polycyclic aromatic hydrocarbons such as fluoranthene,anthracene and pyrene on toy surface can be sensitively detected with PTH-Ag NMs enrichment.