Which instrument is used to sample headspace after a product is prepared for analysis?

• A. Use a pH meter to sample headspace
• B. Sample headspace with PID
• C. Visual inspection only
• D. Test with conductivity meter

Answer: (B)

Headspace sampling focuses on the vapors above a prepared product, so you need a device that detects volatile organic compounds in air. A Photoionization Detector is designed for this purpose: it uses ultraviolet light to ionize VOCs in the gas phase and then measures the resulting current, which correlates with VOC concentration in the headspace. This makes it well-suited for rapid sampling and screening of volatile components right after preparation.

A pH meter measures hydrogen ion activity in liquids, not vapors. Visual inspection can't quantify or detect VOCs in the headspace. A conductivity meter assesses ionic content in liquids, not gas-phase compounds.