Gas Chromatography Mass Spectrometry

Gas spectrometry-mass spectrometry is a combination of both the process of GC and MS. Its purpose is to separate the chemical elements of a certain compound and identify the molecular level component. In the process, the mixture will be heated in order to separate the elements. Once it vaporizes, it passes the column through an inert gas, most likely to be helium, and proceeds to the mass spectrometry process. Once the vaporized compound proceeds to the mass spectrometry process, it will be then separated and its components will be identified through the mass of the analyte molecule.


History

During the 1950’s, Roland Gohlke and Fred McLafferty launched the idea of using mass spectrometry to identify the elements of a compound once they have been separated. Back then, the device they came up with were only limited for laboratory uses because of its room-size feature. However, through the innovation of technology, the size of the device was also minimized. The time it takes for the device to analyze a sample was also accelerated that is why in 1996, the innovated GC-MS device can process a sample at a span of only 90 seconds. This is a lot faster than the first device invented which can finish the process for as long as 16 minutes.


Working the device

In order to execute the two processes, the device for GCMS is combined in one instrument but is divided into two chambers. One is for the gas chromatography and the other for mass spectrometry. The GC chamber consists of a column. The quality of identifying the elements in the compound through its separation depends on the dimension of the column (length, thickness of the film, and the diameter). The time for which the elements of the compound to be separated and come out of the gas chamber called the retention time varies.

Once the separated elements have come out of the gas chromatograph, it then proceeds to the mass spectrometer. Here, the separated elements are taken, ionized, accelerated, bent, and later on identify the elements separately by their mass to charge ratio.

There are some elements which are volatile or easy to evaporate. With this, the elements may not be captures easily and have errors in separation and identification. To solve this problem, the Purge and Trap concentrator is created. The Purge and Trap concentrator works by extracting the analyte and mixes it with water. It is then directed to an air-tight chamber and purged. Purging is done through making the inert gas bubble through water. Once the volatile compound passes through here, the pressure gradient carries them out of the chamber. The volatile compound then passes through the trap or the heated column composed of heated material that returns the compound to its liquid state. Once the compound is returned to its liquid phase in the trap, it will then be heated. After heating, it will be placed afterwards on the gas chromatograph-mass spectrograph.


Advantages of combining gas chromatograph and mass spectrograph

There are several advantages of putting the two devices together in one instrument. For one, it finishes the process faster. The accuracy of both processes is also not attained when they are done separately. This is because the sample to be taken into the mass spectrometer must be in its purest state. Once the process is done separately and the sample is taken out of the gas chromatograph, the sample will be tampered and the results will differ. Also, when they are done separately, there are instances that the separated elements in the gas chromatograph have similar ionized fragment pattern and can be misinterpreted by the mass spectrograph. At least with putting the two devices together in one instrument, the number of errors is reduced.


Applications of gas chromatograph-mass spectrograph

Though the title of the process may seem complicated, understanding the process is not as complicated as it seems. To summarize it all, it is through gas chromatography that the elements of the compound are separated while it is through mass spectrometry that the elements of the compound are named individually. This simple process is used in different scientific purposes that have direct applications on our daily living.


Environmental checking and cleaning

Have you ever wondered how environmentalists said that our air is already polluted? How did they come up with such statement? How did they identify the elements that pollute our air? This is where gas chromatography-mass spectrometry comes in. Supposedly, the air we breathe should only be composed of O2. Through GC and mass spectrometry, the other elements that mixed with O2 that make the air polluted are separated and identified each. Through GC and mass spectrometry, the field of environmental studies has widened.


Criminal Forensics

CSI and NCIS have become the most popular criminal forensic TV series of all times. Have you ever thought how they are able to solve crimes even without much physical evidences? GC and MS are responsible for this. When a person is killed with the use of chemical, the chemical as well as the criminal can be detected through this process. Even without the actual container of the chemical, it can still be detected through the blood sample of the victim. In arson cases, this is a technique used to solve the crime, specifically Pyrolysis Gas Chromatography. This is to identify the elements that caused the fire of the area.


Drug identification

Specific drugs are prohibited on every state. In order to detect whether a person is taking the illegal drugs, GC and MS is applied. Drug test makes use of these processes. Through this, the examiners can identify what drugs have entered the body of the person through their urine, blood, and feces sample.


Security purposes

Since the September 11, 2011 incident, US airports have made their security stricter. To execute this, all incoming and outgoing individuals of the United States have their baggage inspected through Thermo Detection. This process involves GCMS to detect whether the baggage contains explosives.


Analysis of food and beverages for nutrition purposes and perfume

One way to identify the nutrition value of a certain food or drink is through GCMS. Their elements are identified individually and are then analyzed whether they should still be taken or not.


Medicine

Gas chromatography-mass spectrometry now serves as a curing process for newborns to detect whether they have congenital metabolic disease. As doctors have presumed, these diseases are inborn or are instilled in a person upon their birth. Through GCMS, the diseases are detected at an early age through inspecting the metabolic process of the newborn. Once metabolic disorders have been traced, the possible congenital disease can be identified as well.


Outer space activities

This process has been used for astrochemical studies. During the launch of the space probes in Mars, NASA tried to see whether Mars and Earth have similar elements. With the detection of these, they also expected whether the planet can be inhabited by humans. Sadly, the chemical composition of the planet cannot accommodate the needs of humans.

This is also the reason why we wonder whether the other heavenly bodies have been and currently being inhabited by other living creatures, the reason why we question whether we are still alone in the universe or not. This is because through this process, the similarities of elements of both planets have opened a room for mysteries. Since some of the elements present here on Earth are also present in Mars, it is possible to say that there are other living creatures with different structures existing.

Other planets have also been inspected with the help of GCMS. This process led NASA to conclude the impossibility of life in other planets.

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