Research Of Gas Purge Syringe Microextraction System

Solid phase microextraction(SPME), which is solventless, flexible, inexpensive and also sensitive, is usually used in extraction of PAHs, and it plays an important role in pretreatment. But, SPME has low recovery rate and operates hardly. Stainless steel wire can overcome the breakable defects of traditional quartz fiber, so it has been widely used as SPME fiber matrix. In order to develop a sample preparation instrument which use less organic solvent, own high enrichment quality and automated, this dissertation studied and developed a gas purge syringe microextraction system, which belongs to in-tube SPME. The stainless steel syringe without the need for any additional coatings, is used to extract Polycyclic aromatic hydrocarbons (PAHs). The main contents of this dissertation include:First, the STC89C52 processor is selected as the control device. In this system, semiconductor and microheater are designed to cool the extraetion solvent and to heat the sample. Inert gas also can be detected and adjusted by microprocessor control mass flow controller (MFC). PID control algorithm is adopted to export PWM control signal for driving the execution components-refrigeration piece and heater band. In order to improve the utilization of energy, the multichannel extraction and multichannel elution are designed. Eight samples can be extracted at the same time.Then, neural network algorithm is used to optimize the parameters of the experiment. First, a series of micro-extraction experiments are implemented using the gas purge syringe microextraction system. These experimental parameters trained the neural network so the fitting function of recovery is constructed, then optimized experiment parameters.Finally, PAHs and were extracted separately by the gas purge syringe microextraction system and gas chromatography-mass spectrometry is used to analyze.The experimental results show that the recovery of PAHs standard samples reached more than 80%, and the RSD is lower than 10%. Extraction experiments on actual plant samples show that the system acts well in actual sample extraction. The entire extraction process is simple and fast, and it greatly reduced the usage of organic solvents.