Which device uses ultraviolet light to ionize particles for VOC determination? (Alternate phrasing)

• A. Photo Ionization Detector (PID)
• B. Mass Spectrometer
• C. Flame Ionization Detector
• D. Electrochemical Sensor

Answer: (A)

Ultraviolet photoionization is a fast, non-contact way to create charged particles from VOC molecules so you can measure them. A Photo Ionization Detector uses a UV lamp that emits photons energetic enough to ionize many volatile organic compounds. When a VOC absorbs a photon and ejects an electron, the resulting ion and free electron are collected by electrodes, producing a current proportional to the VOC concentration. This approach works well for a broad range of VOCs and provides real-time, portable monitoring with minimal sample preparation. It’s ideal when you need quick screening of air quality and broad sensitivity to organics without chromatographic separation. Other devices differ in how they generate ions: a flame ionization detector uses flame chemistry rather than light; a mass spectrometer uses various ionization methods and then analyzes ions by mass-to-charge ratio, a more complex setup; an electrochemical sensor relies on redox reactions, not light-induced ionization.