利用活性炭吸着及氣體層析法測定空氣中有機溶劑濃度之研究

Method of Determing Organic Vapors by Adsorption on Solid Charcoal Tubes Followed by Gas Chromatography

蘇德勝(Teh-Sheng Su)

《工業安全衛生》 41期 (1981/11) Pp. 41-59

摘要

有機溶劑由於石油工業的發達而被廣泛使用於工業製程：但如其使用不當，則有引起勞工職業中毒及死亡之危險。因此，勞工從事有機溶劑之工作場所應經常實施環境測定以瞭解作業環境之有機溶劑之濃度是否構成勞工的危害，並進一步採取防範措施。有機溶劑之蒸氣濃度測定方法，有比色檢知管法，濕式比色分析法，及活性炭吸着後利用氣體層析法等種類。臺灣目前廣泛使用之測長式檢知管法，雖具簡單方便及經濟等優點，但因其準確度較差及易受干擾等缺陷，在實際從事環境測定時常會產生很大的困擾；同時，一般有機溶劑甚少係單獨存在於作業環境中，因此，須頼氣體層析儀作有效的定性分離及定量之工作。一般採用活性炭管捕集有機溶劑蒸氣具有吸着管容易裝塡、容易搬運、容易操作及儲存容易等優點，且準確度高。如配合個人採樣幫浦之使用，將採集之有機溶劑以二硫化碳溶出後，注入氣體層析儀定量分析可得滿意的個人暴露資料。爲求取活性炭吸着有機溶劑後以二硫化碳溶出，再以氣體層析儀定量其濃度之方法所得數據之眞實度央，必須在實驗室製造一種既知濃度之氣體或蒸氣當作測試標準，以檢定此種採樣分析方法之準確性。一般製造既知濃度氣體之方法有靜態系統及動態系統兩類。動態系統係採用流量稀釋方法，能連續操作，爆炸危險性較低，且氣體表表面吸收之損失較少及準確度較高等優點：因此，本文採用動力擴散系統，以苯及甲苯溶劑爲例，評估上述方法之統計誤差結果：相對準確度苯及甲苯分別爲0.5%及8%；相對精確度苯及甲苯分別爲12%及13%，因其準確度較高，值得國內研究探行。

並列摘要

The sources of organic vapors in the work enviroment are manyan important are being chemical solvent. Some arise as a result of chemical processes, and still others arises as a byproduct. Organic solvents are used as dry cleaning agent, paint thinners, pesticides, chemical agents and liguid extraction agents etc. When an exposure of organic solvents exceeds certain threshold levels, many of effects are harmful, and the individual's health and ability to function efficently may be impaired. In Some cases the effects are irreversible and damage can be permanont. Sampling instruments used to evaluate the environment for occupational hazards are generally classified according to type as direct reading and those which remove the contaiminant from a measursd quantity of air by adsorption, absorption or other methods. Sampling and analytical methods must provide the necessary sensitivity, accuracy, reproducibility, and, preferable, rapid results. Detector tubes are the widely used and abused analytical devices for obtaining direct reading of organic vapor concentrations in working environments. Their simplicity of operation, low initial cost and giving an immediate readout makes them a popular instrument for field use. Nevertheless, these devices have limitations regarding applicability, specificity and accuracy. The commercial gas detector tubes in past years had indicated widespread inaccuracy and other serious problems. The use of charcoal tubes for the collection of solvents is adequate to establish the concentration on organic vapors in air in an area. They are easy to make seal, handle, transport and store and not critically interfered by humidity. The gas chromatographic analysis can be used for simutaneously separation and quantitatively measurement of all compound in a solvent vapor mixiure. A dynamic vapor pressure system was used to generate known concentration of organic vapors in air with benzene and toluene for example for evaluating the validity of charcoal tube-gas chromatographic method. The accuracy of these tests was expressed by the mean relative error which was 0.5% for benzene and 8% for toluene. The precision was expressed by pooled relative standard deviation which was 12% for benzene and 13% for toluene. Therefore,it is recommended to be a convenient optimized method for the analysis of selected solvent vapors in the industrial atmosphere