I conducted a Gas Chromatography experiment using Flame Ionisation Detector (FID).A capillary column was used.

1)Blank
2) Standard
3) Sample
4)Blank
5)Standard
The above was injected into the system.

In 2)Standard chromatogram,a sharp, thin peak was observed between the 2 principal peaks. This peak had area count of less than 100.
This sharp peak was also seen in 4)Blank.

However, this sharp peak was not present in 5)Standard chromatogram.
Can you suggest a reason for this sharp spike/peak seen in 2) and 4)?

I would suspect contamination.

Dear Bob,

Can the sample results be accepted then if we exclude the "integration" of this "peak" from the chromatogram?

I'm not sure what kind of quantitative work you are doing, I would think it could be accepted if the outlying peak was not integrated with the other two peaks AND if the total of the three are not used somewhere.

The sharp peak observed in both the 2) Standard chromatogram and 4) Blank chromatogram, but not in the 5) Standard chromatogram, could indicate the presence of a contaminant or impurity in either the Standard solution or the instrument itself. The fact that it is also observed in the Blank suggests it is not due to the analyte but rather originates from another source.

To further investigate the reason for this peak, you can try the following steps:

1. Evaluate the injection procedure: Ensure that the syringe or injection port is clean and free of any residual materials that could contribute to the observed peak. Contaminants introduced during sample handling or injection could be a potential source.

2. Check the gas flow: Improper gas flows or fluctuations in pressure can lead to the appearance of spurious peaks. Make sure the gas flow rates and pressures are within the recommended range for your specific instrument and column.

3. Column condition: The condition of the capillary column may affect peak shape and the appearance of unexpected peaks. Verify that the column is properly conditioned and that there are no leaks or damage to the column hardware.

4. Investigate the Standard solution: Examine the Standard solution carefully for any impurities or contaminants. It's possible that the spike may originate from a component in the Standard, such as a high-boiling impurity or solvent residue.

5. Analyze the Blank: Compare the Blank chromatogram with the Standard and Sample chromatograms. If the peak is present in both the Blank and the Standard, it suggests that the contaminant is originating from outside the sample or Standard.

6. Further analysis: If the origin of the peak is still unclear, you may need to perform additional tests, such as analyzing the Blank using different conditions or using a different injection technique to pinpoint the source of the spike.

Remember, troubleshooting chromatographic issues often requires a systematic approach, carefully considering each potential contributing factor.