Preparation And Performance Of The Coated-fiber Needle Extraction Material

Sample pretreatment technology plays a very important role during the analysis process. The fiber coating needle extraction technology was newly developed extraction method and could selectively separate based on a specific identification performance of molecular imprinting, using molecularly imprinted polymer coating as the extraction medium. Fiber-coated needle extraction technology has high enrichment performance for very low concentration of volatile organic compounds in the environment. Moreover it has advantages of short extraction time, simple operation, specific selection, etc. It was extensively applied in many fields including biology, environmental science and chemistry.Needle extraction material has many advantages such as simple fabrication, portability, good stability and high mechanical strength. To increase its permeability and the amount of polymer, the fiber coated with molecularly imprinted polymer was packed in the needle. In this paper, benzoic acid molecularly imprinted polymer coating fiber was prepared by the in situ polymerization. Then it was put into the stainless steel needle to prepare the needle extraction material. This material was used to enrich four volatile organic compounds including benzene, toluene, ethyl benzene and o-xylene. The main contents of this paper are as follows:1. The needle extraction material with molecularly imprinted polymers coating fiber was prepared. Firstly, benzoic acid molecularly imprinted polymer was coated on the surface of some fibers by in situ polymerization. Then the fibers were put into a stainless steel needle to get the needle extraction material. The factors that affect the enrichment performance of the material, such as the type of fibers, the number of fibers, the ratio of each material component, reaction time, reaction temperature, a series of desorption conditions were studied. The molar ratio of template molecular / functional monomer / cross linker was 1/3/20. The reaction was conducted at 60 °C for 24 h. The obtained coating fiber was characterized by SEM. The extraction performance of the prepared material for BTEX was studied. The limit of detection of the method was lower than 0.02μg/L. The results showed that the needle extraction material of molecularly imprinted polymer coating fiber has high selectivity and enrichment capability.2. The needle extraction material coupled with gas chromatograph was used to extract BTEX. The enrichment capability, permeability, accuracy, reproducibility, storage performance and service life of the material were studied. The results showed that the prepared needle extraction material has good permeability with less extraction time and high enrichment capability. It can be continuously used for 80 times. The RSD% of run-to-run and needle-to-needle extraction reproducibility are both less than 8%. Finally, the material was applied for the actual environment sample analysis and the results displayed it has high enrichment capability and selectivity.