Application of Low-Temperature Glassy Carbon-Coated Macrofibers for Solid-Phase Microextraction Analysis of Simulated Breath Volatiles

With increasing interest in the detection of disease-related volatile organic compounds (VOCs) found in human breath, breath analysis could prove to be a very useful diagnostic tool, especially for the early detection of lung cancer. Solid-phase microextraction (SPME) is a technique well suited for breath analysis and has been applied to studying VOCs in the nanomolar concentration range. However, many compounds of interest in human breath are excreted at picomolar concentrations and may be unsuitable for analysis using conventional SPME sorbent phases. To extend the concentration range of conventional SPME, a novel 4-cm-long, low-temperature glassy carbon (LTGC) macrofiber was developed. The LTGC SPME macrofibers were used to extract five lung cancer-related VOCs (2-methylheptane, styrene, propylbenzene, decane, undecane) at conditions simulating human breath, and they were analyzed via gas chromatography/mass spectrometry. Results show that detection limits are lower using the SPME macrofibers compared to a conventional SPME fiber, in the low- to sub-picomolar range for the compounds of interest, which should be adequate for the analysis of these compounds in human breath. Also, the LTGC SPME macrofibers demonstrate significantly greater extraction efficiencies, sensitivity, and peak identification accuracy compared to that of commercial PDMS/DVB fibers without excessive chromatographic peak broadening. The use of SPME macrofibers broadens the potential range of application of SPME where the rapid extraction of very low levels of volatile compounds is required.