Gas Chromatography (GC)

Gas Chromatography is a type of chromatography used for analyzing compounds that are volatile or can be vaporized at higher temperatures without decomposition. Organic compounds with ionizable functional groups, such as alcohols, amines, carboxylic acids, are often not volatile enough for use with GC, however, they can be easily derivatized via silylation, methylation, etc. to generate volatile derivatives for GC-based analysis.

GC-MS and GC-FID techniques are performed at Emery Pharma with customized method development, validation, method transfer (USP, EP, BP, JP, etc.), library matching for unknown analytes, and custom analyte library generation. We specialize in detecting and quantifying low parts per million (10-6, ppm) and ultra-trace levels of analytes, i.e. sensitivity in the range of ppb or parts per billion (10-9), from complex mixtures.

Emery Pharma utilizes GC-MS and GC-FID techniques in both liquid injection and thermal desorption methods (including SPME) and USP/FDA Headspace sampling for volatile impurities including residual solvents. We are experienced in derivatization sample prep for poorly volatile analytes.

We are happy to be the partnering lab for clients requiring analysis of hard to solve problems. Please contact us today to learn more about our services and let us know how we can be your bridge to success on your next analytical project.

Typical examples of GC-FID, GC-MS, HS-GC analyses include:

  • Trace impurities in Active Pharmaceutical Ingredients (APIs)/ Drug Products (formulations)
  • Toxicological screening tests
  • Blood-Alcohol Content (BAC) testing
  • Residual solvents analysis in drug samples
  • Volatile Organic Compounds (VOC) from complex solid or liquid matrices (wastewater, soil specimen, etc.)
  • Environmental analysis (emerging contaminants in water such as dioxins, herbicides, pesticides, phenolic and polyphenolic compounds, Poly Aromatic Hydrocarbons (PAHs), Poly Chlorinated Biphenyls (PCBs), etc.)
  • Food, beverage, and fragrance analysis
  • Odorous compounds and natural oils
  • Trace impurities in cosmetics
  • Fatty acid profiling
  • Metabolic tracer studies

Instrumentation and Libraries:

  1. Agilent 6890N GC with FID, Agilent Chemstation software package
  2. Agilent 6890N GC with 5973 Network MSD, Agilent Chemstation software package
  3. Agilent G1888 Headspace autosampler
  4. Multiple mass libraries, including the one from NIST, from which we can search and provide quick identification for the components in these and other samples.

Background and Instrumentation:

GC is commonly used with the following detectors:

1. GC-MS utilizes a mass spectrometer usually based on Electron ionization (EI) for analyte detection and quantification. GC-MS analysis has long been used to identify unknown compounds as well as quantify compounds down to low and ultra-trace levels from complex mixtures. This can be the technique of choice for a large proportion of regulatory work or quality control, to identify using NIST compound library, and quantify components present at low levels. This analysis is also one of the key practices used for organic mixture analysis (Figure 1).

Figure 1. GC-MS chromatograms analysis performed at Emery Pharma for several commercially available Essential Oils (eucalyptus, lemon grass, clove bud, garlic, and citronella oils) for known and unknown natural products.

2. GC-FID utilizes a flame ionization detector, based on the principle of flame pyrolyzation of carbon-containing compounds for analyte detection and quantification. This technique is particularly suitable for hydrocarbons, offering picogram (10-12) level sensitivity.

HS-GC-MS Analysis:

Our instruments are equipped with headspace autosampler set up for our clients’ needs.

HS-GC analysis is particularly suitable for trace levels of analytes, where the sample matrix is complex and not suitable for direct injection for GC-MS analysis. In such cases, volatile species in the sample are partitioned into the “headspace” gas volume from the matrix. Headspace GC may be used for analysis of both liquid and solid matrices.

The team at Emery Pharma can conduct such tests with samples sizes ranging between 0.1 to 10 g for use via headspace GC-MS. The required sample size for HS-GC is inversely proportional to the known concentration of the volatile compound that must be detected or quantified. We can also perform quantitative analysis, which would often require a larger sample amount for use with a standard addition method.