Applications of Open-Path Fourier Transform Infrared for Identification of Volatile Organic Compound Pollution Sources and Characterization of Source Emission Behaviors
Abstract An open-path Fourier transform infrared spectroscopy (OP-FTIR) system was set up for 3-day continuous line-averaged volatile organic compound (VOC) monitoring in a paint manufacturing plant. Seven VOCs (toluene, m-xylene, p-xylene, styrene, methanol, acetone, and 2-butanone) were identified in the ambient environment. Daytime-only batch operation mode was well explained by the time-series concentration plots. Major sources of methanol, m-xylene, acetone, and 2-butanone were identified in the southeast direction where paint solvent manufacturing processes are located. However, an attempt to uncover sources of styrene was not successful because the method detection limit (MDL) of the OP-FTIR system was not sensitive enough to produce conclusive data. In the second scenario, the OP-FTIR system was set up in an industrial complex to distinguish the origins of several VOCs. Eight major VOCs were identified in the ambient environment. The pollutant detected wind-rose percentage plots that clearly showed that ethylene, propylene, 2-butanone, and toluene mainly originated from the tank storage area, whereas the source of n-butane was mainly from the butadiene manufacturing processes of the refinery plant, and ammonia was identified as an accompanying reduction product in the gasoline desulfuration process. Advantages of OP-FTIR include its ability to simultaneously and continuously analyze many compounds, and its long path length monitoring has also shown advantages in obtaining more comprehensive data than the traditional multiple, single-point monitoring methods.
Field evaluation of a transportable open-path FTIR spectrometer for real-time air monitoring.
To effectively and accurately evaluate human exposures to chemicals, it is important to quantify mixtures of chemicals in air, at low levels, and in real time. The purpose of this study was to evaluate, in the field, a prototype of a new transportable instrument that can fill an important gap in methods available to industrial hygienists. This instrument is a cross between extractive and open-path Fourier Transform Infrared spectrometers and measures chemicals passively and in real time in the vicinity of the breathing zone. The spectrometer has a folded optical path that can be enclosed, similar to an extractive system. The enclosure can be removed, enabling the optical path to be open to the atmosphere; thus, the instrument could be operated as an open-path spectrometer. A field study was conducted in three different occupational settings, including a prosthodontics dental laboratory, a surgery recovery area, and a cytology laboratory. Chemicals that were identified and quantified included methyl methacrylate, nitrous oxide, xylene isomers, toluene, and ethanol. Simultaneous side-by-side sampling was conducted with the prototype instrument and recognized National Institute of Occupational Safety and Health (NIOSH) analytical methods. The distinct infrared "fingerprint" of each chemical made identification and quantification of multiple chemicals possible with the prototype instrument. This attribute allowed the industrial hygienist to quantify short-term exposures and ceiling levels, correlate work practices with concentration levels, evaluate the effectiveness of engineering controls, and identify the presence of unexpected compounds. There was no significant difference between the mean time-weighted averages (TWAs) of the prototype instrument and traditional methods (p > 0.03). Regression analysis found good correlation between the two methods with no significant differences between the slope and unity and between the y-intercept and zero (p > 0.03). The technology and design of the prototype instrument incorporated a unique combination of features and advantages not found in other methods or instruments. The instrument produced results comparable to recognized analytical methods under field conditions and shows promise as a powerful tool in industrial hygiene air monitoring applications.
Phenomenology and Existentialism
Chapter 1 Preface to the 2001 Edition Chapter 2 Introduction Part 3 The Phenomenology of Edmund Husserl Chapter 4 The Attack on Psychologism Chapter 5 The Phenomenological Reductions Chapter 6 Phenomena and Phenomenological Reflection Chapter 7 Intentionality Chapter 8 Meaning and Constitution Chapter 9 Essences and Necessary Truth Part 10 Existential Phenomenology Chapter 11 Phenomenology and Ontology Chapter 12 Existence Chapter 13 The Life World Part 14 Self and Others Chapter 15 Consciousness and the Ego Chapter 16 Intersubjectivity Chapter 17 Freedom Chapter 18 Existentialist Ethics Chapter 19 Bibliography