Development Of Multi-channel Gas-liquid Microextraction System

As a new environmentally friendly sample pretreatment technology,liquid phase microextraction technology is popular among analysts because of its advantages of low solvent consumption,simple operation and short processing time.The trend of modern sample preparation technology is rapid,high-volume processing,high automation,low reagent volume,little environmental pollution,high precision,high reliability,and high reproducibility.The existing liquid phase microextraction system can only perform one set of experiments,and it is impossible to automate the pretreatment process entirely,and can not satisfy the process of automatic combination of subsequent analysis instruments.To overcome the shortcomings of the existing liquid phase micro-extraction system and meet the development needs of the automated and intelligent sample pretreatment system,this dissertation researched and developed a multi-channel gas-liquid micro-extraction system.Firstly,this thesis designed a multi-channel gas-liquid micro-extraction structure based on the liquid phase microextraction technique gas flow purging sample and realized the automatic elution function by improving the technology.At the same time,the extraction system was automatically combined with gas chromatography.Methods.The high-temperature heater was designed according to the gas chromatographic temperature-programming vaporization technology,and the syringe pump was created for the automatic elution process.The experimental prototype was made by taking the three-channel system as an example to complete the assembly and debugging of each hardware.Secondly,the heater control circuit,condenser control circuit,gas flow controller control circuit,syringe pump drive circuit,single-chip interface circuit,and power supply circuit were designed.Software design and testing of various functions of the system were completed.Finally,the experimental results of the heating condensing temperature control performance in the extraction system were tested to obtain the minimum time required for sample extraction at different temperature.The liquid delivery accuracy of the syringe pump was tested so that the relative standard deviation between the three channels was less than 1%.Manual injection experiments and automatically combined experiments were carried out using polycyclic aromatic hydrocarbon standard samples,and the experimental results were analyzed.The recovery rates of the samples were all greater than 70%,and the relative standard deviation between channels was less than 15%.