Gas Chromatography Rapid Solid Sampling Technique And The Helium Discharge Light Ionization Detector

At present, the trends in development of gas chromatography (GC) are mainly going towards two aspects:quick detection and field analysis by portable GC. Based on these tendencies, two related research works for GC were developed and summarized in this thesis. In the first work, a direct solid sample introduction method for GC was developed to detect pesticide residue in crops. The proposed method was quick and simple since there was no need for any sample pre-treatment during the analysis. Thanks to these advantages this method was suitable for quick detection for pesticide residue in crops and large-scale screening of sample, which enhanced the efficiency for the detection. In another work, a helium discharge photo-ionization detector (He-PID) was developed to work as a GC detector. He-PID possesses advantages like simple structure, miniaturization and high sensitivity. Besides, He-PID is a universal detector which is capable of detecting most of the volatile organic compounds. Therefore, He-PID is a potential detector for portable GC Discussions about the above research works are summarized in the following chapters:In Chapter One, the background and purpose for this research were demonstrated. Quick detection and field analysis by portable GC has been the trends in development of GC. Recent developments of related techniques were introduced, especially in direct sampling and photo-ionization detector.In Chapter Two, an analytical method for GC using direct solid sample introduction was developed to tackle the problem regarding quick detection of pesticide residue in crops and large-scale screening of samples. Solid sample without sample pre-treatment was directly introduced into a modified split/splitless injector for GC analysis. A split/splitless injector was modified to quickly remove oxygen and low boiling-point matrices of the sample. The whole sampling procedure was simple and it required less than 5 minutes. Recovery, linear range, reproducibility, precision, LOD and LOQ are used as the validation for this proposed method. Experimental results indicated that this proposed method was feasible for the detection of pesticide residue in crops, and its quick and simple characters would be potentials for the detection for large-scale screening of crop sample.In Chapter Three, the research for helium discharge photo-ionization detector (He-PID) was conducted. He-PID is one of the GC detectors which use helium-gas-discharge as an ionization source to ionize the analytes eluted from the column. This work was firstly started with the design of the detector, the following researches including the material of the detector components, detector processing, installation of the detector, sizes, working-condition of helium discharge, flow rate of the He-support gas, etc, were studied. The follow-up studies were discussed at the end of this chapter.