Characterizing dynamic atmosphere generation system performance for analytical method development.

A significant portion of the work of developing and validating methods for volatile organic compound (VOC) sampling in workplace atmospheres involves the use of laboratory-generated atmospheres. The sample variability was evaluated from the dynamic atmosphere generation system used for VOC atmosphere generation and sampling. Characterization of the bias and variability of samples was done for a variety of atmospheres containing neat n-heptane and mixtures of VOCs sampled on activated coconut shell charcoal.

Method development for on-site monitoring of volatile organic compounds via portable TD-GC-MS: evaluation of the analytical performances of HAPSITE ER instrumentation and thermal desorption sampling media.

Determining worker exposure to hazardous volatile organic compounds (VOCs) in air at levels exceeding the Permissible Exposure Limits and Recommended Exposure Limits established by the U.S. federal agencies of Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH), respectively, will continue to be an important part of environmental and occupational health risk assessments.

A field-portable colorimetric method for the measurement of peracetic acid vapors: a comparison of glass and plastic impingers.

A method for measuring peracetic acid vapors in air using impinger sampling and field-portable colorimetric analysis is presented. The capture efficiency of aqueous media in glass and plastic impingers was evaluated when used for peracetic acid vapor sampling. Measurement of peracetic acid was done using an -diethyl-p-phenylenediamine colorimetric method with a field-portable spectrometer.

Controlled generation of peracetic acid atmospheres for the evaluation of chemical samplers.

A system for controlled generation of peracetic acid (PAA) atmospheres used to test and evaluate sampling and measurement devices was developed and characterized. Stable atmospheric conditions were maintained in a dynamic flow system for hours while multiple sensors were simultaneously exposed to equivalent atmospheres of PAA vapors. Atmospheres characterized by a range of PAA concentrations at a controlled flow rate, temperature, and humidity were generated.

A Visual Hydrogen Sensor Prototype for Monitoring Magnesium Implant Biodegradation.

Alternative metals such as magnesium (Mg) and its alloys have been recently developed for clinical applications such as temporary implants for bone and tissue repair due to their desirable mechanical properties and ability to biodegrade harmlessly by releasing Mg, OH, and H as biodegradation products. The current methods for monitoring Mg-alloy biodegradation are either invasive and/or costly, complex, or require large equipment and specially trained personnel, thus making real-time and point-of-care monitoring of Mg-alloy implants problematic. Therefore, innovative methods are critically needed.

Indicator Dyes and Catalytic Nanoparticles for Irreversible Visual Hydrogen Sensing.

Using ultraviolet-visible (UV-vis) absorption spectroscopy, we have tested the reactivity of various indicator molecules combined with catalytic bimetallic gold-palladium nanoparticles (Au-Pd NPs) in solution for an irreversible and visual response to H. Our aim was to identify the most suitable indicator/Au-Pd NP system for the future development of a thin, wearable, and visual H sensor for noninvasive monitoring of Mg-implant biodegradation in research and clinical settings with fast response time. The indicators studied were bromothymol blue, methyl red, and resazurin, and the reactions of each system with H in the presence of Au-Pd NPs caused visual and irreversible color changes that were concluded to proceed via redox processes.