按照《工作场所有害物质监测方法》中的要求,提出了热解吸-气相色谱法测定工作场所空气中二氟二氯甲烷的方法,空气中的二氟二氯甲烷用活性碳吸附采样,随后在热解吸仪中使活性碳中的被测物质热解吸,并引入气相色谱中.以氢焰离子化检出器进行检测,二氟二氯甲烷浓度在0~2 000 mg·L-1之间呈线性,相关系数为0.998 7,方法的检出限为8.5×10-2mg·L-1.在3种不同浓度水平(500,1 000,2 000 mg·L-1)进行方法的精密度试验,所得RSD值在2.0%~4.6%之间.根据试验数据算得每100 mg活性碳对二氟二氯甲烷的穿透容量为20 mg,对不同浓度的二氟二氯甲烷的热解吸效率均在90%以上,所提出的方法适用于工作场所空气中二氟二氯甲烷的现场监测.

A method of thermal desorption gas chromatographic determination of difluorodichloro methane in air over workshop was proposed according to the requirements mentioned in reference.Difluorodichloro methane in air was sampled by active carbon,from which it was desorbed by the thermo-desorbing instrument,and introduced directly into the gas chromatograph.After separation on the FFAP column,the object compound was detected by the hydrogen flame ionization detector.Linear relationship was found in the range within 2 000 mg·L-1 (r=0.998 7) of difluorodichloro methane.Detection limit of the method was found to be 8.5×10-2mg·L-1.Precision of the method was tested at 3 different concentration levels (500,1 000,2 000 mg·L-1) and values of RSD′s obtained were in the range of 2.0%-4.6%.Permeability capacity calculated from the experimental data was 20 mg of difluorodichloro methane for each 100 mg of active carbon.The desorption efficiency for different concentration of difluorodichloromethane were all larger than 90%.The proposed method was suitable to be used for worksite monitoring of difluorodichloro methane in air over the workshop.