What kind of analysis would you like to have performed using GC-MS? We offer a metabolomics approach as a service.

i have six samples of essential oils and i need to determine the Chemical compositions

You have to add an internal standard before analysis using GC or GC-MS then calculate.

The chemical composition of an essential oil can be very complex. The determination of chemical composition depends on what you want to know. Analysis of an oil that has not been characterized may begin with qualitative analysis. In this step, a chromatogram is obtained, spectra and retention indices are obtained, and compounds present are identified. There can be hundreds of compounds present - some endogenous to the plant, others present as contaminants (like pesticides). Quantitative analysis can take one of several forms. If there is a specific list of analytes, either arising from a qualitative analysis or from some other source, one obtains pure compounds and a suitable internal standard, calibrates the system and makes quantitative measurements. Another form of quantitative analysis assumes that the response factors for all compounds in an essential oil are similar in value and area percents are used to estimate relative concentrations of one compound to another.