Date of Graduation

5-2019

Document Type

Thesis

Degree Name

Bachelor of Science in Chemical Engineering

Degree Level

Undergraduate

Department

Chemical Engineering

Advisor/Mentor

Roper, Keith

Committee Member/Reader

Berry, Keith

Abstract

Polyurethane swabs are a common instrument for environmental sampling in the food, medical, and forensic fields due to their high recovery of organisms like viruses, spores, and bacteria. For sampling microbes in food and medical facilities, storage of the collected samples occurs under the absence of light to promote growth for more accurate testing. In the forensic fields, microbial growth results in sample contamination so the inhibition of this growth requires the drying of the swabs. This work studies the evaporation rates of water from polyurethane swabs under zero watt incident light, 30 W fluorescent bulb, 50 mW 532 nm laser, and surfactant dopant conditions to determine the effects of each condition on the swab recovery. Overall, the zero-watt incident light condition resulted in the lowest evaporation rates without surfactant dopant, but with surfactant dopant, the zero-watt incident light had evaporation rates higher than that of the 30 W fluorescent light bulb. Under 50 mW laser irradiation, the evaporation rate of water from the polyurethane swabs was consistently higher under all conditions. A dynamic period was observed when irradiating the swabs with the laser, which showed that from 0-60 s, the laser resulted in lower evaporation rates but after 60 s, the laser irradiation resulted in higher evaporation rates than the other conditions. These results showed that for food and medical fields needing the swabs to have reduced water evaporation; use of swabs doped with surfactant would allow for increased intake as well as reduced evaporation, while forensic science fields could use a 532 nm laser to dry the swabs to minimize microbial growth.

Keywords

Triton X-100, Sampling Devices

Available for download on Friday, October 16, 2020

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