Gas chromotography-mass spec percent composition

In summary, the conversation was about conducting a lab to prepare and analyze standard solutions of diesel/biodiesel mixtures and an unknown sample. They used a GC-MS instrument to obtain gas chromatograms and mass spectra, both in terms of relative abundance. The goal was to estimate the percent composition of biodiesel in the unknown sample using the relative abundance of the biodiesel peak compared to the sum of all other peaks. They also discussed the role of the mass spectrum in identifying the biodiesel peak.
  • #1
Puchinita5
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So I conducted a lab where I prepared 4 standard solutions of diesel/biodisel mixtures and then analyzed a diesel/biodeisel sample of unknown composition.

We put all the samples into a GC-MS instrument (gas chromotograph-mass spectrograph).

I have a gas chromatogram for all samples and then a mass spectrum of the highest two peaks in each chromatogram.

Both the chromatograms and mass specs are in terms of relative abundance.

I am supposed to determine (i was told I could estimate) the percent composition of biodiesel in the unknown.


Can someone help me understand how I can use the gas chromatograms and mass specs to figure this out?

Can I just take the relative abundance of (whatever I determine to be) the biodiesel peak over the sum of the relative abundances of all other peaks?

What can the mass spec tell me? Is it just to help me figure out which peak is biodiesel and which is diesel?

I am not understanding this!
 
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  • #2
Puchinita5 said:
Can I just take the relative abundance of (whatever I determine to be) the biodiesel peak over the sum of the relative abundances of all other peaks?

That's only an approximation, but should work if you have no other data.
 

1. What is gas chromatography-mass spectrometry (GC-MS) percent composition?

Gas chromatography-mass spectrometry (GC-MS) percent composition is a technique used to determine the relative abundance or percentage of each component in a sample. It combines the separation capabilities of gas chromatography with the detection and identification capabilities of mass spectrometry.

2. How does GC-MS percent composition work?

In GC-MS percent composition, the sample is first vaporized and then passed through a gas chromatography column. The different components in the sample separate based on their physical and chemical properties. The separated components then enter the mass spectrometer, where they are ionized and fragmented. The resulting mass spectra are used to identify and quantify the different components in the sample.

3. What are the advantages of using GC-MS percent composition?

GC-MS percent composition offers several advantages over other analytical techniques. It provides high sensitivity and specificity, allowing for the detection and identification of even trace amounts of components in a sample. It is also highly versatile and can be used to analyze a wide range of compounds, including volatile and non-volatile substances.

4. What types of samples can be analyzed using GC-MS percent composition?

GC-MS percent composition can be used to analyze a variety of samples, including liquids, solids, and gases. It is commonly used in the analysis of pharmaceuticals, food and beverage products, environmental samples, and forensic evidence.

5. What are some common applications of GC-MS percent composition in research and industry?

GC-MS percent composition has numerous applications in both research and industry. It is commonly used in the analysis of organic compounds in various fields such as chemistry, biology, and environmental science. In industry, it is used for quality control, product development, and process monitoring in industries such as pharmaceuticals, food and beverage, and oil and gas.

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