(An) evaluation of the analytic methods of ethylene oxide following pre-treatment
OSHA method 50에 따라 HBr-coated charcoal tube를 사용하여 산화 에틸렌(ethylene oxide, EO)을 측정시 나타나는 문제점은 기기분석을 위한 전처리 방법의 절차가 복잡해서 분석상의 오차가 발생할 가능성이 높다는 것이다. 따라서 본 연구는 HBr-coated charcoal tube에 포집된 EO를 전처리 할 때, 용매 및 유도체화에 따른 탈착효율 및 정밀도를 비교평가하여 정확도와 정밀도가 높으면서도 분석절차가 간편한 방법을 제시하고자 하였다.
이를 위하여 OSHA method 30에서 제시한 benzene:CS2(99:1) 용매로 탈착한 시료와 OSHA method 50에서 제시하는 n,n-dimethylformamide(DMF)로 탈착한시료 및 DMF로 탈착후 2-bromoethylheptafluorobutyrate로 유도체화 시킨 시료의 검출한계(limit of detection, LOD), 통합변이계수(pooled coefficient of variation, pooled CV), 탈착효율(desorption efficiency, DE) 그리고 탈착 후 안정성(stability)을 비교하였다. 연구결과는 다음과 같다.
선형 회귀식에 의해 산출한 EO의 LOD는 benzene:CS2(99:1)로 탈착하였을 때 2.483ug/㎖이었고, DMF로 탈착한 분석결과는 1.919ug/㎖이었으며, DMF 탈착 후 유도체화 시킨 시료의 분석결과는 1.301ug/㎖으로 나타났다.
EO 분석결과의 pooled CV는 benzene:CS2(99:1)용매로 탈착하였을 때 0.00503이었고, DMF로 탈착한 결과는 0.00329이었으며, DMF 탈착 후 유도체화 시킨 결과는 0.00514이었다.
EO의 탈착효율은 benzene:CS2(99:1)용매로 탈착하였을 때 92.13%이었고, DMF로 탈착한 분석결과는 102.75%이었으며, DMF로 탈착 후 유도체화 시킨 결과는 96.47%이었다.
EO의 탈착 후의 안정성은 benzene:CS2(99:1)용매로 탈착 후, 하루 지난 뒤의 분석결과는 당일 결과의 96.81%이었고, DMF로 탈착 후의 결과는 97.13%이었으며, DMF로 탈착하여 유도체화 시킨 분석 결과는 95.69%이었다. 이 값들은 OSHA method 50에서 제시하고 있는 5%미만의 감소기준에 모두 적합하였다.
결론적으로 HBr-coated charcoal tube에 포집된 EO 분석시에, DMF로 탈착한 후 바로 분석하는 것이 다른 방법에 비해 분석절차가 간편하면서도 정확도와 정밀도가 높은 분석방법인 것으로 나타났으며, 탈착 후 24시간동안 시료의 안정성도 확보 되었다.
Following the OSHA method 50, problems occur when measuring the Ethylene oxide, EO, using a HBr-coated Charcoal tube. The problems are that for the machinery-analysis necessary for the pre-treatment process, the sample, after desorption, must go through more than 3 stages of analysis in order to create the EO inducing substance, 2-bromoethylheptafluorobutyrate, and must also be transferred more than twice into new vials. Through such complicated processes, it is highly possible for errors to occur during the analyzing process.
As such, our lab, when handling the EO of the HBr-coated charcoal tube, compared and studied the efficiency and preciseness of the solvent and derivatives'' desorption in order to simplify the analyzing process while heightening precision and accuracy of the analyzing method.
To achieve this, the desportion sample of the benzene:CS2(99:1) given by the OSHA method 30, the desportion sample of n,n-dimenthylfomamide(DMF) given by OSHA method 50, and the sample that was derivativized with 2-bromoethylheptafluorobutyrate after desorption by DMF were studied and compared for their limit of detection(LOD), pooled coefficient of variation(pooled CV), desorption efficiency(DE), and stability after desorption. The results were as follows:
The EO''s LOD was 2.483ug/sample when using the solvent, benzene:CS2(99:1), and 1.919ug/sample after desorption using DMF. The result of the sample that passed DMF desorption and was derivativized was 1.301ug/sample.
EO''s pooled CV was 0.00503 when using the solvent benzene:CS2(99:1), after desorption with DMF, the result was 0.00329, and the result of those derivativized by DMF desorption was 0.00514.
EO''s DE using the solvent benzene:CS2(99:1) was 92.13%, after desorption with DMF, it was 102.75%, and the result of those studied after being derivativized by DMF desorption was 96.47%.
EO''s stability for the sample with the solvent benzene:CS2(99:1), comparing result of next-day analysis to same-day was 96.81%, after desorption with DMF, it was 97.13%, and the result of those studied after being derivativized by DMF desorption was 95.69%. These results were in accordance with the less than 5% given by OSHA method 50.
In conclusion, during the analysis of the EO in the HBr-coated charcoal, analysing immediately after desorption by DMF is more simple, precise, and efficient than other analysing methods, and the stability of the sample 24 hours after desorption was also established.