Residual solvent risk is a function of the process. Water and ethanol are low-risk; hexane, ethyl acetate, and methanol need tighter controls. GC — often headspace GC with flame ionization or mass spectrometric detection — is the standard way to measure what remains.

How the method works

A sample is heated in a sealed vial so volatile compounds partition into the headspace, which is injected onto a GC column. Compounds are separated by boiling point and interaction with the stationary phase, then detected and quantified against standards.

Headspace sampling reduces matrix interference and is well suited to powders that do not dissolve cleanly. The method must be validated for the specific solvents and matrix, and the reporting limits should be below the limits that apply to the destination market.

What it can prove

  • The concentration of targeted volatile solvents in the sample.
  • Whether the lot meets the agreed solvent limits.
  • A process-relevant contaminant record for the batch.

Where it stops

  • Only detects the solvents in the panel.
  • Non-volatile or thermally labile residues need a different method.
  • A generic panel may miss a solvent specific to the process.

Which solvents to test

The panel should follow the extraction and drying process. An ethanol–water extract does not carry the same risk as a hexane extract, and a spray-dried powder may carry solvents from the carrier or drying step. Regulatory frameworks such as ICH Q3C group solvents by class and set limits; the buyer's market may add its own requirements.

Ask for the individual results, not a generic compliance statement. If a solvent was not used, it does not need to be tested — but the supplier should be able to explain the process and the panel logic.

Reading the result on a COA

  • Check that the panel matches the extraction and carrier system.
  • Compare results with the limits for your market.
  • Ask for individual results, not a summary.

What to ask a supplier

01

Which solvents were used in the process?

02

Which solvent classes and limits were applied?

03

Can you provide individual results and reporting limits?

Related terms

AnalysisResidual solventsChemistryCarrierDocumentsCertificate of analysis

References and further reading

External links are provided for orientation. Methods, limits, and acceptance criteria differ by market and product; confirm the applicable requirements with your regulatory advisor.

Cite this page

Rainwood Botanical. "Gas chromatography for residual solvents for botanical extracts." October 2026. https://ingredients.rainwoodbio.com/resources/methods/gc-residual-solvents/