The optimization of low volume-SPME method for volatilomics analysis of exhaled breath condensate

The analysis of breath can provide insight into the metabolic state of the body. However, the collection, transport, and storage of breath samples present certain challenges. The collection of exhaled breath condensate (EBC) emerges as a promising method for breath analysis. Despite this, the volume of EBC is relatively low, necessitating a sensitive method capable of extracting analytes from a small sample volumes. Therefore, this study aimed to develop and optimize a robust and green solid-phase extraction method for the analysing volatile organic compounds (VOCs) of various polarities in a low-volume EBC using a statistical design of experiment (DoE).
Based on the screening experiments and DoE, the optimal conditions were determined to be 15 min equilibration time, and 20 min of extraction at 44 °C using DVB/CAR/PDMS fibre in direct immersion (DI) mode. The method was validated for linearity, precision and accuracy, yielding satisfactory results. The optimized method was applied to quantify the concentration of selected VOCs in real samples collected from a healthy subject, as well as after consumption of coffee and smoking of an electronic cigarette. Many of the selected compounds are associated with diseases and are challenging to detect in specimens from a healthy subject, but this method can measure them as potential disease markers.
The proposed method enables the analysis of VOCs is very low-volume samples (200 µL), which is particularly important for studies involving body fluids. Notably, the applied approach demonstrated that different VOCs, representing various chemical classes and polarities, can be detected and quantified.