The Environmental Protection Administration Executive Yuan announced the “Emission Standards for Hazardous Air Pollutants from Stationary Pollution Sources” (draft) in 2019. There are 72 important hazardous air pollutants planned to develop the emission standards according to a three-stage schedule. The research method is based on NIEA A807, Method 10, and Method 8270E for sampling and analytical development of Nitrobenzene, Bis(2-ethylhexyl)phthalate, Hexachloroethane, Benzidine, 4,4'-Methylenebis(2-chloroaniline), Hexachlorobenzene, and Polychlorinated biphenyl.
The project aims to establish appropriate survey technology of the aforementioned pollutants, and the factors of collection efficiency, chromatography instrument optimization analysis conditions, applicable concentration range, storage conditions, and possible interference and removal methods caused by moisture, etc. should be considered. And then the research must be evaluated according to the "Environmental Testing Standard Method Verification Procedures Guidelines" set by the Environmental Analysis Laboratory, EPA. In the final report, the draft of development of sampling and analytical methods for semi-volatile organic compounds in stacks must be proposed, and that meets the specifications of the method format.
In the beginning, each analyte was tested by GC/MS with reference to the NIEA M731 method. The calibration curve was verified by internal standard, and the results show that the standard deviation (RSD %) complies with the technically acceptable requirements of the method (<30%). Nevertheless, the results of detection limit compared with the project's estimated emission standards, showing that PCBs, 4,4'-Methylenebis(2-chloroaniline) and Hexachlorobenzene didn't meet the requirements of the regulatory standards (after calculation of the perimeter distance of 1 meter). To achieve better results, this research is based on the recommended method of Method 8270E, and the tandem mass spectrometer (GC/MS/MS) is used to test the analytical conditions.
The tandem mass spectrometer (GC/MS/MS) test results of the calibration curve show that the relative standard deviation (RSD %) complies with the technically acceptable requirements of the method (<30%), except for Benzidine. Referred to NIEA M731 method, the concentration of Benzidine is prone to reduce due to oxidation when the solvent is concentrated, resulting in its poor spectrum. The GC/MS/MS test results show that Dichloromethane has a better extraction recovery rate than Toluene. Currently, only Benzidine and MOCA are still poor in GC/MS/MS analysis after extraction with Dichloromethane. It also pointed out that the pretreatment process of Benzidine and MOCA may have non-repeatable spectrum, oxidation and low sensitivity during storage, therefore, CLA 2101 method of the Labor Commission of the Executive Yuan is referred to test.
Referring to CLA 2101 method, Benzidine and MOCA used Methanol (containing 0.17% Diethylamine) as the desorbent and then were analyzed by HPLC/UV. There are great recovery rate that Benzidine and 4,4'-Methylenebis(2-chloroaniline) reach 80.0 ~ 97.1% and 97.8 ~ 110.2% respectively. However, the MDL of 4,4'-Methylenebis(2-chloroaniline) cannot meet the requirements of regulatory standards (the distance is 5 meters). Thus, a further suggestion is to use HPLC/MS/MS to obtaining a lower MDL.
There are 4 samplings of stacks in the domestic factory completed. Although some samples are affected by the complexity of the exhaust gas affecting quantitative and DEHP needs to further confirm the storage conditions, the outcomes indicate the viable development of investigative techniques. Besides, two sessions of technological diffusion were held in June and October 2019 respectively. In conclusion, the draft program of sampling and analytical methods for semi-volatile organic compounds in stacks is proposed to provide future reference of the detection technology.