| The gas chromatography/mass spectrometry (GC/MS) that has been developed for more than half of a century is a technique for separation and analysis, and the application of it is very mature and widespread. In gas chromatography (GC), the different distribution coefficient of varied samples between stationary phase and mobile phase leads to the different time of varied compounds flow out of the column, so the compounds can be separated. GC provides two-dimensional signals, which are retention time and intensity, so we can obtain two-dimensional chromatogram. The quantitative basis is peak height or peak area. As a quantitative analysis method, GC is an effective method for separating the compounds because of the high performance separating power and high sensitivity. Mass spectrometry (MS) is an analytical technique that measures the mass (m)-to-charge (z) ratio of charged particles due to their movement regular patterns in the magnetic and electric fields. It measures mass of ions and intensity distribution. The characteristics of MS are that it can give us the molecular weight of compounds, elemental composition, empirical formula and molecular structure. The predominance of MS is their high qualitative feature, high sensitivity, and rapid determination. GC/MS provides an effective method for qualitative and quantitative analysis of compounds.In recent years, on-line instruments have been developed into miniaturization and their functions are multivariate along with the development of computer and electron technology. The whole performance, stability, and reliability of the instruments have been improved because of the application of computer. At the same time, the application of intelligent software makes people get rid of the traditional hand work and instruments run automatically day and night. So the time that both the new methods to develop and the samples to operate need are all shortened, and the analysis is high-grade and high efficiency. The automatization, manipulation sensitivity and workability of instruments have been improved largely due to the powerful software function. After endeavor for more than half a century, GC/MS has been improved greatly in separation, detection, and data collection. It has been a very mature and perfect analytic tool for qualitative and quantitative analysis.The thinking in design of MS Software Platform bases on modularization and outstanding professional function. In this thesis, the design and implement of program called ITMSTuning have been discussed. ITMSTuning is data collection software in instrumental software platform, and the main function of ITMSTuning is as following: switch control and parameters tuning of instrument, the selection of scan pattern and scan parameters configuration, real-time display of collected data, to save the scanned data and instrument parameters and so on.The main works are illuminated as follows:(1)Switch control and instrument tuning 16-DO and 16-DA are designed in this software for the instrument can be better controlled, which control the switch and tune the instrument respectively. Through controlling the opening and closure of pre-pump and turbo molecular pump, we can get vacuum state that GC/MS need when they are working. Similarly, the state of GC/MS injector, multiplicator, and filament is also controlled by switch. And in order to calibrate the instrument, instrument tuning is necessary. We can get needed data such as resolution, sensitivity, accurate mass measurement and ion abundance ratio etc. through modulating parameters of ion source, mass analyzer and detector and so forth.Furthermore, in order that the functional mode of instrument can be monitored better, 16-DI and 32-DA are designed in the software to ensure that the instrument can reach specified performance index.(2)Scan pattern and scan parameters configurationThis part is an emphasis of the thesis. We mainly discussed two modes .They are full scan and selected ion monitoring (SIM). Full scan is a mode that most in common use. The scan mass range cover with the mass of molecular ions and fragment ions of measured compounds, so spectrum is the whole spectrum of compounds, then we can do spectrum base index. SIM does not scan a certain mass range continuously, but scan several selective mass ranges in skip mode. We can't get the whole spectrum by SIM and it is mainly used to measure target compounds and impurity of complex compounds.One scan mass value corresponds to one scan voltage value. The scan voltage of the instrument should start from zero when it is working, and then the instrument collects data when it reaches at the scanning area. At last the scan voltage value falls down to zero after data collection. So the scanning process of this program is divided into scan segment, and each segment should be configured according to the request which includes whether collecting scan mass value corresponding to this segment scan voltage value or not, to ascertain the collected number of points, to set up scan voltage frequency and to ascertain scanning segment duration and so on. In order to get better collected data, the scan segments have been preprocessed in this program.(3)Display of collected dataDisplay of collected data is implemented through ActiveX widget in the main interface. The data collected through hardware will interfered by instrument parameters, background samples and so on, so the application program still provides simple processing(smooth, smoothing) for better peak shape. In addition, the peak parameters of mass spectrogram can be setup through application programs, so as to make discriminant function work better. At the same time, to limit the numbers of collected peaks, we can set up a threshold according to signal level of background noise for reaching to the collected standard.(4)To save the scanned data and instrument parametersThe scanned data and instrument parameters are saved in the XML file which memorized in ASCII code. ASCII is widely supported by various platforms and XML mode that aiming at data file layout can be issued extensively. Otherwise, as an interface standard that publicized by W3C, DOM is the application program interface for development and programming of XML file, and it is inter-platform and independent of language. Besides, Microsoft Corporation has provided a XML syntax resolver called MSXML.dll dynamic chained library which in fact is a COM object library that package all objects when XML analysis. In this thesis, program each part of discussing above with VC++ language, because COM is a reuse object that is expressed by binary format and is independent of language.The collected data of mass spectrogram are saved as peak outline drawing. The data size stored is so large that the recurrence of collected data is possible and it is beneficial to compare and research afterwards. Furthermore, the information of scan parameters can be real-timely saved and load. It is convenient to tuning of the instrument.MS software platform is composed of lots of programs. The discussion in this thesis is just about data collection. Lots of contents are made into dynamic chained library, in order that they can be applied conveniently to other MS software systems and provide convenient conditions for code share afterwards... |
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