Evolution of photoionization detectors: Challenges and new opportunities

The increasing impact and significance of volatile organic compound (VOC) has led to a growing demand for portable and rapid analytical techniques. Among the available technologies, photoionization detector (PID) has emerged as a widely used solution due to their sensitivity, fast response, and ease of integration into compact systems. However, a consistent limitation reported across the literature is the relatively poor selectivity of PIDs when distinguishing between chemically similar VOCs in complex mixtures. In this review, we provide a detailed examination of the current technologies employed in PID systems, examining photoionizer designs, materials, and their operating principles. Particular attention is given to the limitations these technologies face, as well as the emerging strategies aimed at overcoming existing barriers and enabling the next generation of PID.