In VOC sorbent sampling, breakthrough occurs when...

• A. When the sorbent becomes saturated and analyte passes through
• B. When the sorbent material changes color
• C. When the instrument detects a spike
• D. When humidity condenses the sample

Answer: (A)

Breakthrough occurs when the sorbent becomes saturated and the analyte passes through. In VOC sorbent sampling, air is drawn through a trap that adsorbs the volatile compounds. As the volume of air or the concentration of VOCs increases, the sorbent’s adsorption sites fill up; once they’re exhausted, additional VOC molecules can no longer be retained and begin to move past the sorbent, potentially being lost or captured only later in the train. This leads to underestimation if sampling continues without accounting for it. Other phenomena like a color change, a spike in the instrument, or condensation due to humidity are not what defines breakthrough themselves.