气相色谱-质谱法

Gas Chromatography-Mass Spectrometry (GC-MS)

GC-MS combines two powerful techniques to identify compounds with low detection limits and enable potential quantitative analysis. It is well-suited for analyzing liquid, gas, and solid samples, though the target compounds are typically volatile or semi-volatile.

GC-MS is part of our Smart Chart Series. Additionally, it can separate complex mixtures of compounds for identification and quantification.

How GC-MS Works

1. Gas Chromatography (GC) Step:

   • The sample is vaporized and carried by an inert gas through a coated glass capillary column.

   • The "stationary phase" is bonded to the column’s interior.

   • Retention time is the duration a compound takes to travel through the column to the detector.

   • Compounds are identified by comparing their retention times to reference standards.

2. Mass Spectrometry (MS) Step:

   • Compounds eluting from the GC column are fragmented via electron impact ionization.

   • Charged fragments are detected, and the resulting mass spectra are used for molecular identification.

   • The fragmentation pattern is reproducible and enables quantitative measurements.

Sample Compatibility

GC-MS analyzes liquids, gases, and solids:

• Liquids/Gases: Typically injected directly into the GC.

• Solids: Require solvent extraction, outgassing (thermal desorption), or pyrolysis.

Specialized Sampling Techniques:

• Thermal Desorption:

  • Conducted under helium flow at controlled temperatures (40–300°C).

  • Analytes are collected on a cryogenic trap during desorption.

  • Sample chamber dimensions: 1.25" × 4" cylinder.

• Pyrolysis:

  • Used for materials incompatible with direct GC-MS injection.

  • Samples are heated (up to 1400°C) to decompose molecules reproducibly.

  • Smaller resulting fragments are analyzed by GC-MS.

Other Sample Prep Methods:

• Derivatization

• Static headspace analysis

• Purge-and-trap

• SPME (Solid-Phase Microextraction)
  Selected based on sample type and target species.

Ideal Applications

• Identification/quantification of volatile organic compounds (VOCs) in mixtures

• Outgassing studies

• Residual solvent testing

• Trace impurity detection in liquids/gases

• Extractables assessment in plastics

• Contaminant analysis on semiconductor wafers (via thermal desorption)

Strengths

• Separation and identification of organic components in complex mixtures

• Quantitative analysis

• Trace organic contaminant detection:

  • Liquids: Mid- to low-ppb levels

  • Solids: Nanogram-level sensitivity (dynamic headspace)

Limitations

1. Target compounds must be volatile or derivatizable.

2. Non-volatile matrices (wafers, oils, metals) require extraction/outgassing prep.

3. Challenging for atmospheric gases (CO₂, N₂, O₂, Ar, CO, H₂O).

Technical Specifications

• Detected signals: Molecular ions and characteristic fragment ions

• Mass range: Up to *m/z* 800

• Detection limit: ~1 ng introduced to the column

Why Choose EAG?

We provide GC-MS services for diverse materials, delivering:

• Fast turnaround times

• Accurate data

• Personalized support to ensure actionable insights

Next Step: Complete the form to consult our experts on how GC-MS can analyze your materials.