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Gas Chromatography

Gas chromatography is a physical method of separation in which the components to be separated are distributed between two phases. Robertson Microlit offers a variety of Gas Chromatography (GC) services, including unknown solvent screening and residual solvent analysis. Headspace options are also available. Feel free to reach us for further information. Please note that all GC analysis requests should be communicated to us prior to submission to ensure that we are able to meet your specific requirements. When requesting GC analyses, please complete our GC-MS/GC-FID Request Form.

The most commonly used detector is the flame ionization detector (FID). Flame ionization detectors are widely used in gas chromatography because of their sensitivity to a wide range of components and ability to work over a wide range of concentrations. The FID detector is also quite robust and can measure organic substance concentration at very low and very high levels, with a linear response of 106.

USP <467> Residual Solvents
Residual solvents are typically determined using chromatographic techniques such as gas chromatography. There are many different solvents which may be used in pharmaceutical manufacturing. Residual solvents are separated into three classes based on risk assessment or their potential toxicity level. The objective of this general chapter is to provide acceptable amounts of residual solvents in pharmaceuticals for the safety of the patient.

Gas Chromatography-Mass Spectrometry (GC-MS) is capable of separating volatile and semi-volatile compounds in complex samples and is the method of choice for qualitatively and quantitatively evaluating samples containing a number of components. GC-MS has excellent linearity as well as an even lower limit of quantitation than that obtained by GC-FID and is capable of identifying unknown compounds that are present in a sample.

Unknown Scans by GC-MS
The actual identification of an unknown can be performed using GC-MS. Unknown scanning is a service offered for identification of unknown compounds by searching against a mass spectral database. A compound can not only be identified by its mass spectrum, but also by comparison of its retention time to that of a standard.

Headspace Analysis
Headspace gas chromatography is most suited for the analysis of the very light volatiles in samples that can be efficiently partitioned into the headspace gas volume from the liquid or solid matrix sample. The analysis of residual solvents in pharmaceutical products can benefit from this technique. Other common applications include industrial analyses of monomers in polymers and plastic, flavor compounds in beverages and food products, and fragrances in perfumes and cosmetics.