The objective of this project was to develop sampling and analytical methods for N-methyl pyrrolidinone (NMP), isobutanol (IBA), ethylene glycol (EG), diethanolamine (DEA), and acetic acid (HAc) in ambient for Environmental Analysis Laboratory, EPA to establish standard operation methods. Based on previous study, all the compounds were planned to be sampled using stainless steel tubes or impinges, and then measured by TD-GC/MS or IC system. Due to the highly difference of physical properties, such as boiling points, ranging from 108 to 270 °C, saturated vapor pressures, ranging from 15.7 to 0.00014 mmHg, and viscosities, the sampling and analytical methods were categorized into two parts. NMP, IBA, EG were sampled using stainless steel tubes and measured by TD-GC/MS. DEA and HAc were sampled using impinges and measured by IC system.
Based on our study results, the R values of calibration curves of all the five compounds were higher than 0.995. As for method detection limits (MDLs), NMP was 3.59 μg/m3, IBA was 0.70 μg/m3, and EG was 72.32 μg/m3 when sampling 3 liters, and DEA was 2.48 µg/m3 and HAc was 2.51μg/m3 when sampling 60 liters. As for preservation tests, the recoveries of all the five compounds were better than 90 % after storing at 4±1 °C for 14 days. Based on the field sampling results, except IBA, the concentrations of NMP and EG in ambient were lower than prepared concentrations, and therefore the safe sampling volume was estimated above 6 liters. For the compounds sampled by impinges, the capture efficiency of DEA was 73.2~111.5%, and the capture efficiency of HAc was 102.4~107.6 %. The precisions of NMP, IBA, EG, DEA, and HAc were 2.3 %, 1.8 %, 4.8 %, 0.75 %, and 0.58 %, respectively. The accuracies of NMP, IBA, EG, DEA, and HAc were 97.6~106.9 %, 93.9~100.8 %, 92.5~112.2 %, 98.7~101.7 %, and 109.9~112.5 %, respectively.
The sampling and analytical methods developed in this project were proven to be practical by surveying the ambient air samples around 7 factories. Besides, two technical communication seminars were taken place on July and November. All the study results were reported in the technical draft for EPA’s reference.