(150e) Detection of the Tuberculosis Volatile Organic Biomarker Methyl Nicotinate in Breath Using Electroactive Solutions (EAS)

Tuberculosis (TB) is a significant global health threat with the WHO reporting 1.4 million people deaths in 2019[1]. Breath biopsy methods present as a promising resource for TB diagnosis as it conjunctively negates the need for sputum collection that can cause many problems in young or ill patients and can provide results at the point-of-care. Methyl nicotinate (MN) has been identified by GC-MS as a specific biomarker of mycobacterium tuberculosis not readily found in the breath of healthy individuals[2], however routine testing through this method is inhibited by high operating costs and the undersupply of specially trained technicians. This semi-volatile biomarker has high solubility in water compared to other compounds found in breath. When passing breath into the EAS, it creates a well-filtered, concentrated sample ready for analysis electrochemically.

Our lab’s electrochemical breath biopsy method utilizes a cobalt Engineered Electroactive Solution (EAS) to analyze samples on inexpensive, commercially available screen-printed electrodes via square wave voltammetry (SWV). The change in signal of a transition metal of known electrochemical activity is observed when the solution is exposed to an analyte of interest. These results show cobalt EAS to be both sensitive and specific to methyl nicotinate, responding to biomarker levels found in patient breath, with a limit of detention of approximately .01 mM MN. A unique peak for MN is observed with peak heights that proportionately increase with biomarker concentration. Furthermore, the use of cobalt EAS for detection of MN in mimicked patient breath samples shows that the diffusive gas to liquid transfer process adequately purified samples of potential confounders, resulting in negligible interference in detection.

[1] World Health Organization, “Status of the TB epidemic,” 2019.

[2] Syhre, M. and Chambers, S.T., 2008. The scent of Mycobacterium tuberculosis. Tuberculosis, 88(4), pp.317-323.