Which detector requires the sample to be exposed to ultraviolet light to ionize the sample?

Which detector requires the sample to be exposed to ultraviolet light to ionize the sample?

• A. Photo Ionization Detector
• B. Gas Chromatometer
• C. Infrared Sensor
• D. Electrochemical Sensor

Answer: (A)

Photo Ionization Detectors operate by using ultraviolet light to ionize the molecules in the sample. When the UV photons hit ionizable species, electrons are ejected, creating positive ions and free electrons. An electric field collects these charges and converts the ionization current into a signal proportional to the concentration of ionizable compounds in the air. This approach is particularly sensitive to volatile organic compounds, especially aromatic and unsaturated ones, because they have relatively low ionization energies and respond strongly to UV irradiation. Infrared sensors detect molecules by absorbing specific infrared wavelengths and measuring changes in light, not by creating ions. Electrochemical sensors rely on redox reactions at an electrode to generate a current, independent of UV ionization. Gas chromatography is a separation technique; the detector used with GC (such as FID or ECD) relies on different detection principles and does not require UV-induced ionization.

Photo Ionization Detectors operate by using ultraviolet light to ionize the molecules in the sample. When the UV photons hit ionizable species, electrons are ejected, creating positive ions and free electrons. An electric field collects these charges and converts the ionization current into a signal proportional to the concentration of ionizable compounds in the air. This approach is particularly sensitive to volatile organic compounds, especially aromatic and unsaturated ones, because they have relatively low ionization energies and respond strongly to UV irradiation.

Infrared sensors detect molecules by absorbing specific infrared wavelengths and measuring changes in light, not by creating ions. Electrochemical sensors rely on redox reactions at an electrode to generate a current, independent of UV ionization. Gas chromatography is a separation technique; the detector used with GC (such as FID or ECD) relies on different detection principles and does not require UV-induced ionization.