The Simultaneous Analysis of Aliphatic Chlorides in Air by Gas Chromatography ╱ Mass Spectrometry

• Main Authors: YANG,Shwu Jiuan, 楊淑娟
• Other Authors: LIN,Ping Jei
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/83642863265832227122

碩士 === 逢甲大學 === 化學工程研究所 === 81 === The pretreatment in trace analyses for organic polluants in ambient air were necessary in Capillary column gas chromatogra- phic techniques． The concentration and desorption processes of the pretreatment were complex， time tedious，and might cause un- certain results． In this investigation ，a fourteen aliphatic chlorides (from C1 to C3) mixture sample has been analyzed by direct injection in packed column gas chromatography． Since the fourteen aliphatic chlorides were not completely separated by any single liquid phase packed column in gas chro- matography． The optimal separations of the mixed sample (Exclu- sion of 1，1 ，1-trichloroethane and dichloromethane) was found from the window diagram of two liquid phases with weight percen- tages of 70% OV-17 and 30% FFAP． The relative separation time ( Separation factor，alpha) of the poorest couple was 1．11 in the quantitative analysis of the mixed sample by using a two meters column packed with the above percentages of the liquid phases in mixed bed method． All fourteen aliphatic chlorides were measured quantita- tively in four different concentrations individually by using Gas Chromatohraphy ╱ Mass Spectrometry (GC╱MS) ． Although 1，1，1- trichloroethane and dichloromethane were unable to be separated from the other twelve compounds，the characteristic fragment of those compounds，C2H3Cl2+ and C2H2Cl2+ ，were chosen to avoid the peak overlap from other compounds in the selective ion mode (SIM) method of the GC╱MS．The concentration of the fourteen compounds were obtained under the SIM method in sub-ppm levels with iodobu- tane as an internal standard． The results for chloroethane was even sensitive to ppb levels． The linear dynamic range of our mass spectrometer detector was over 3 orders of magnitude．