密闭舱内VOCs现场快速定量检测技术与装置研究

Study on an On-site Rapid Quantitative Analysis Device for Volatile Organic Compounds in Sealed Cabin

该文发展了可对压强变化的密封舱实现计量采样-富集的采样技术,基于薄壳金属筒式低功耗均温色谱柱组件,结合微池热导检测器/小型氢火焰离子化检测器,建立了一种对密闭舱内挥发性有机物(VOCs)进行现场快速定量检测的方法和装置。根据负压罐和密封舱的压强差值和绝压值以及温度,计算出有效采样体积(折算到标准大气压),进而计算出富集倍数。当有效采样体积为100 mL时,对甲苯的富集倍数大于400倍。所研制的色谱柱组件将色谱柱紧密排绕在薄壳式金属筒外层,加热丝紧密排绕在金属筒内侧,可实现小于0.4℃的均温效果和40℃/min的程序升温速率。在以10℃/min加热至300℃过程中,功耗低于35 W,300℃恒温加热功率仅需28 W。将色谱柱组件的分离性能(包括半峰宽、柱效、分离度和重复性)与实验室进口色谱仪炉箱得到的结果进行对比,发现两种加热方式得到的色谱分离性能相当。采用多种VOCs样品对采样-富集性能进行评价。在高速分离模式下,5 min内可实现53种VOCs的快速分离,半峰宽均小于0.8 s。研制出的整机已应用于烃类、苯系物、醇类、醛酮类等多种VOCs的快速分析,并与商品化便携式气相色谱或气相色谱-质谱的性能参数进行了对比,结果满意。

In this paper,an on-site rapid quantitative analysis device of volatile organic compounds(VOCs)in sealed cabin was developed.The device was based on the metrological sampling-enrichment technique with thin-shell metal cylinder type capillary column heater,and micro thermal conductivity detector/micro flame ionization detector.To adapt pressure change in sealed cabin,a fix-volume vacuum tank with a pressure sensor and a temperature sensor was used to calculate the effective sampling volume and the enrichment factor.The enrichment factor was 400 for toluene at an effective sampling volume of 100 mL(converted to standard atmospheric pressure).The column assembly was constructed by wrapping the heating wire and column on the inside and outside layers of a thin-shell metal cylinder,respectively.The temperature uniformity of capillary column was less than 0.4℃,and a temperature programming rate of 40℃/min was obtained.In the heating process from 40℃to 300℃at 10℃/min,the power consumption was less than 35 W,while at an isothermal temperature of 300℃,the power consumption was only 28 W.The separation performances,including peak width at half height,column efficiency,resolution and repeatability of the column assembly were evaluated and compared with a laboratory chromatograph,proving that the separation performances of the two heating methods were similar.The sampling-enrichment performance was evaluated with varieties of VOCs samples.In the high speed separation mode,53 VOCs could be separated within 5 minutes using a peak width at half height less than 0.8's for all analytes.The developed device was applied to the rapid determination of hydrocarbons,benzene homogeneous,alcohols,aldehydes,ketones and other VOCs.The performance parameters of the device were satisfactory,compared with those of commercial portable gas chromatography(GC)or gas chromatography-mass spectrometry(GC-MS).