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Gas Chromatograph/Mass Spectrometry (GC/MS) Instruments Maintenance Management, Support, and Repair

Category Chemical/Explosives
Type Analytical
Ease of Use 2 out of 5
Determination Capability 5 out of 5

GC/MS has long been considered the “gold standard” for analytical laboratories. It is a strong analytical tool that uses the time it takes for the chemical to travel through the GC’s column, the retention time (RT), compared to known standards to identify the chemical. This is a good technique for simple mixtures and for situations where the chemicals of concern are known and calibrated before running samples.

How GC/MS works - two part analysis

  1. The GC separates mixes of chemicals into individual components.
  2. The MS fragments the chemicals into unique patterns or spectra.

As the chemicals exit the GC column they enter the high vacuum chamber of the MS where the chemical is exposed to an ionization source that breaks apart the chemical into a number of ionized fragments. By controlling the ionization energy and “tuning” the MS, a reproducible fragmentation pattern (spectrum) is created and compared to a reference database (library) of over 150,000 chemicals.

A good GC retention time combined with a solid MS spectral match makes this a truly definitive gold standard identification. With proper calibration and verification, the GC/MS can also determine the concentration of the chemicals detected.

First responders

First Responders, however, typically don’t know what chemicals they are responding to ahead of time and do not have the luxury of time to spend calibrating and verifying chemical targets before they run samples. Instead they use the GC to separate the chemicals to obtain clean spectra for matching and the MS for unknown identification. This is not considered a definitive analysis in this mode but is still an excellent tool to identify chemicals. Since this instrument is often used for chemical agents like Sarin, the retention times for chemical agents are often known. As a result, GC/MS is considered the highest quality analysis for chemical agents and Toxic Industrial Chemicals (TICs).


Limitations with GC/MS include instrument maintenance. The MS part of the instrument operates under high vacuum. Understanding and following manufacturer recommendations for vacuum maintenance is critical to ensuring this instrument will work when needed.

A second limitation is the range of chemicals that the instrument is scanning. Both the GC and MS portion of this type of instrument need to be optimized for the types of chemicals of concern. For example, an instrument that is configured mainly for volatile chemicals won’t detect very high molecular weight chemicals or very low molecular weight chemicals. It is important to understand how the instrument is configured to ensure chemicals of concern aren’t missed.

KD Analytical supports GC/MS Instruments

KD Analytical offers a suite of services for GC/MS instruments (as well many other analytical instruments) that can save you money and time and help you to guarantee the readiness of your equipment and team.

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