Gas sensors, such as chemoresistors and functionalized quartz microbalances and other types, often exhibit limited selectivity, necessitating their integration into sensor arrays. Through the utilization of statistical analysis techniques, these arrays can collectively provide enhanced selectivity. However, it is important to note that the selectivity achieved by electronic noses is artificial in nature. Consequently, despite their ability to discriminate between different samples, electronic noses do not provide insights into the specific gases or volatile organic compounds (VOCs) being detected. This inherent limitation poses challenges in understanding the precise analytes detected by electronic noses, further emphasizing the need for complementary analytical techniques to identify and characterize specific gas or VOC targets.

Proton transfer reaction mass spectrometry (PTR-MS) is a powerful and fast analytical technique that can be used simultaneously with sensors to help understand which molecules they are detecting. In addition to this reference technique role, PTR-MS can also be used to better understand the sampling process and thus optimize it.