How Headspace Sampler Works?
Headspace is used to analyze volatile compounds in liquid and solid samples that cannot be injected directly into a gas chromatograph (GC). Examples would be creams and lotions, blood, soil, electronic components, and polymers. Headspace sampling can accommodate virtually any matrix.
The Headspace Sampling Process
Sample is transferred to a vial suitable for headspace analysis and immediately capped to minimize loss of volatile components.
Once the headspace vial is capped, these low-boiling compounds begin to migrate between the sample and the headspace layer, ultimately reaching equilibrium The time to establish equilibrium is sample-dependent and is determined experimentally.
This time is optimized by incubating the vial in an oven or other temperature-controlled environment.
Once equilibrium is established, the sampling process can begin. The valve and loop design involves three basic steps:
Step 1: increases the pressure within the vial by feeding in additional gas.
Step 2: vents some of that pressure within the vial, effectively back-filling the sample loop with the gaseous phase of the sample.
Step 3: turns the sampling valve, which injects the sample through the transfer line and into the GC inlet for analysis.
Read also: Headspace Oxygen Levels in Pharmaceutical Products
Resource Person: Mohammed Elsayed