顶空气相色谱法测定聚乙烯中挥发性烃类

Determination of volatile hydrocarbons in polyethylene by headspace gas chromatography

本试验采用顶空气相色谱仪,以标准曲线法定量测定聚乙烯中挥发性烃类含量,通过研究顶空进样器平衡温度和时间以及色谱柱分离效果对试样测定的影响确定最佳实验条件。结果表明,测定聚乙烯粒料中的挥发性轻烃含量的最佳条件为选用HP-PLOT Al 2O 3/S色谱柱(50m×0.53 mm×15μm),色谱条件为柱箱起始温度40℃,程序升温190℃保持10min,进样口温度250℃,柱流量8mL/min,顶空条件为平衡温度130℃,平衡时间150min;在最佳条件下测得低密度聚乙烯粒料中的挥发性烃类甲烷、乙烷、乙烯、丙烷、丙烯、异戊烷、正丁烷、1-丁烯、异丁烯含量分别为2.0、5.9、0.32、0.45、0.98、43.4、9.3、1.9、11.4mL/m^(3),相对标准偏差为0.34%~2.76%;高密度聚乙烯粒料中的挥发性烃类甲烷、乙烷、乙烯、丙烷、丙烯、异丁烷、正丁烷、1-丁烯、异丁烯含量分别为15.0、488.8、5.1、7.5、2.3、707.0、437.7、6.3、15.7mL/m^(3),相对标准偏差为0.53%~2.72%;该方法的加标平均回收率为97.83%~102.20%,方法检出限为1.0×10^(-6)mL/m^(3)。

In this test,headspace gas chromatograph was used to quantitatively determine the content of volatile hydrocarbons in polyethylene by standard curve method.The optimal experimental conditions were determined by studying the effects of equilibrium time and temperature of headspace sampler and separation effect on the sample determination.The results showed that the determination conditions of volatile hydrocarbons content in polyethylene granules were optimized as follows,HP-PLOT Al2O3/S chromatographic column(50m×0.53mm×15μm),the starting temperature of column box was 40℃,the programmed temperature was 190℃and maintained for 10 minutes,the sample inlet temperature was 250℃,the column flow rate was 8 mL/min;the headspace condition was as follows,the equilibrium temperature was 130℃,and the equilibrium time was 150 minutes;the contents of volatile hydrocarbons,including methane,ethane,ethylene,propane,isopentane,isobutane,butane,1-butene and isobutylene in low density polyethylene granules were 2.0,5.9,0.32,0.45,0.98,43.4,9.3,1.9,11.4 mL/m3,respectively,and the relative standard deviation was 0.34%-2.76%.The contents of volatile light hydrocarbons,including methane,ethane,ethylene,propane,propylene,isobutane,butane,1-butene and isobutylene in high density polyethylene granules were 15.0,488.8,5.1,7.5,2.3,707.0,437.7,6.3,15.7 mL/m3,respectively.The relative standard deviation was 0.53%-2.72%,the average recovery was 97.83%-102.20%,and the detection limit was 1.0×10^(-6)mL/m^(3).