PID is used to detect which type of substances?

PID is used to detect which type of substances?

• A. Gases with high humidity
• B. Temperatures
• C. Volatile Organic Compounds
• D. Pressure changes

Answer: (C)

Photoionization detectors work by using ultraviolet light to ionize molecules in the air. Molecules that have relatively low ionization energy—most volatile organic compounds—are ionized and produce a measurable current. The detector's signal correlates with the concentration of these organic vapors, making it especially useful for spotting solvents, fuels, and other VOCs at trace levels. It’s not intended to measure environmental parameters like humidity, temperature, or pressure, which require other kinds of sensors. So the substance type detected by a PID is volatile organic compounds.

Photoionization detectors work by using ultraviolet light to ionize molecules in the air. Molecules that have relatively low ionization energy—most volatile organic compounds—are ionized and produce a measurable current. The detector's signal correlates with the concentration of these organic vapors, making it especially useful for spotting solvents, fuels, and other VOCs at trace levels. It’s not intended to measure environmental parameters like humidity, temperature, or pressure, which require other kinds of sensors. So the substance type detected by a PID is volatile organic compounds.