A gas chromatography-mass spectrometer would be used to determine ______ in a sample.

• A. metals
• B. inorganic compounds
• C. organic compounds
• D. elements

Answer: (C)

Gas chromatography-mass spectrometry is designed to separate and identify volatile and semi-volatile organic compounds in a sample. The gas chromatograph vaporizes the sample and passes the components through a column, separating them by volatility and interactions with the column. As each component elutes, the mass spectrometer ionizes it and records a mass spectrum, providing a distinctive fingerprint that can identify the compound and, with calibration, quantify it. This combination makes GC-MS ideal for organic molecules such as solvents, hydrocarbons, pesticides, and other carbon-based compounds.

Metals, inorganic compounds, and elemental species are not typically analyzed by GC-MS because they are not generally volatile under GC conditions and require other techniques (like AAS, ICP-MS, or ICP-OES) for detection and quantification. Therefore, the best answer is organic compounds.