MP 81X is a fixed transmitter utilizes Photo-ionization Detection (PID) technology to monitor Volatile Organic Compounds (VOCs) at resolutions of 1 ppb and 10 ppb. A built-in heater prevents condensation of moisture in the transmitter under high-humidity conditions. Innovative designs of the ultraviolet (UV) 10.6 eV lamp and electrometer reduce contamination, producing more accurate and stable readings and extending maintenance intervals. Mobile apps and a Bluetooth controller make on-site configuration, testing, and trouble-shooting easy and handy. The OLED display is visible from a distance even under strong lighting, while data and alarms are continuously sent to a controller wirelessly or via cables. Major applications include VOC emission monitoring around petrochemical plants, manufacturing and processing facilities.