19 Colorimetric Assay for Pneumonia Screening Via the Volatile Organic Breath Biomarker, Heptane

Faculty Mentor: Swomitra Mohanty (Chemical Engineering, University of Utah)

Pneumonia is the single largest infectious cause of death in children worldwide. Diagnosing pneumonia through a rapid and proactive method would increase the speed at which patients are treated and can recover. Volatile organic biomarkers (VOBs) are present in the breath of patients infected with pneumonia. One such VOB is heptane, which has been proven to be present in the breath of pneumonia patients. Pneumonia is usually diagnosed via chest X-ray, an expensive method of examination. This method of diagnosis is done after patients begin to exhibit symptoms. By engineering an inexpensive device that would detect heptane from the breath in an efficient way through colorimetry, patients could be diagnosed before symptom onset and treatments could start before damage could be done. To confirm the presence of heptane as one of the VOBs associated with pneumonia, staphylococcus aureus was cultured in our laboratory and the released VOBs were measured using GCMS. Heptane is of particular interest as it reacts with water bromine when exposed to UV light in a halogenation reaction. The water bromine loses its characteristic orange-red color during the reaction. Thus, this reaction can detect heptane in patients’ breaths in a point-of-care Pneumonia screening device. Colorimetric methods are used to analyze the concentrations of compounds. The concentration of a colored compound can be determined with a spectrophotometer. Utilizing a blue LED and an OPT101 monolithic photodiode, the concentration over time of water bromine within the water bromine heptane reaction was attained in a spectrophotometer. The engineered spectrophotometer in the initial part of this project was designed to run the heptane water bromine reaction within a cuvette between a blue LED and OPT101 monolithic photodiode. The spectrophotometer was characterized via calibration and used to detect concentration changes from the water bromine and heptane reaction.