Date of Award

Summer 8-6-2021

Degree Type


Degree Name

Master of Science - Environmental Sciences


Environmental Science

First Advisor

Dr. Sheryll Jerez

Second Advisor

Dr. I-Kuai Hung

Third Advisor

Dr. Yuhui Weng

Fourth Advisor

Dr. Yanli Zhang


Stephen F. Austin State University (SFASU) Department of Environmental Science has recently invested in a gas chromatograph which can be used to analyze air samples for volatile organic compounds (VOCs) such as benzene, toluene, ethylbenzene, and xylenes (BTEX). The goal of this project was to develop a standard operating procedure (SOP) and modify the current method for the detection of VOCs associated with oil and gas drilling activity to accommodate the equipment and capabilities of SFASU Environmental Assessment Lab. This study aims to provide the framework for future research in air quality monitoring in the Eagle Ford Shale area. An SOP has been developed for the SFA Environmental Assessment Lab and details materials, lab procedures, gas chromatograph (GC) analysis, field sample collection procedures, and operation and maintenance of the GC. A modified method of analysis for BTEX has been developed based on EPA Method TO14A and method validation parameters are discussed. Ambient air samples were collected from gas stations in Nacogdoches, Texas to evaluate whether the method is capable of detecting BTEX in air samples. Samples at the refueling level consistently had sufficient concentration of VOCs within the analysis capabilities of the current method parameters. Samples at the breathing level and property line levels consistently returned analysis results of less than the limit of quantitation

(LOQ). It was possible to see peaks in the respective retention windows on most breathing level chromatograms and some property line chromatograms, however the peaks could not statistically be differentiated from noise. Concentrations of toluene, ethylbenzene, and xylenes identified by the modified method of analysis were well below the National Institute for Occupational Health and Safety (NIOSH) recommended exposure limit (REL) and Occupational Safety and Health Association (OSHA) permissible exposure limit (PEL). The LOQ for these VOCs were also well below the respective protective levels. This indicated that the modified method was adequate for analyzing toluene, ethylbenzene and xylenes for protective purposes. Concentrations of benzene identified by the modified method of analysis were well above the NIOSH REL and OSHA PEL. The LOQ for benzene was above one of the protective levels. This indicated that the method may not be adequate for analyzing benzene for protective purposes.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.



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