Another question is, whenever i want to run standard sample, diluted with water. The analysis failed and "failed leak test" pop up at the headspace screen. However, when i run sample, no issue happen. May i know if the standard sample diluted with water is not recommended to inject to headspace GC ?
Nur Fatinie Mazlan Headspace GC-FID is designed to analyze the volatile components present in a sample. If your sample does not contain volatile compounds or if their concentration is too low, no peaks will appear in the chromatogram.
Ensure that the GC-FID system is correctly set up and calibrated. Issues such as improper column installation, incorrect detector settings, or a malfunctioning injector system can lead to a lack of detectable peaks.
In headspace analysis, the sample preparation technique is crucial. Ensure that the sample is prepared in a way that allows for the volatiles to be efficiently released into the headspace.
The "failed leak test" message indicates that the system is detecting a leak somewhere in the headspace analysis pathway, which is more pronounced when analyzing water-diluted standards.
Water can be challenging for headspace analysis because it has a high capacity for absorbing heat, which can affect the equilibrium between the liquid phase and the headspace. Furthermore, water does not always vaporize well in the headspace, potentially leading to pressure inconsistencies that might be interpreted as a leak.
When working with water or aqueous solutions, ensuring a proper seal in the vial is crucial. Water's properties can sometimes compromise the seal integrity, leading to leak detection. Make sure that the vials are correctly capped and that the septa and caps are suitable for aqueous samples.
Check the instrument's operating parameters. For water-diluted samples, adjustments may be needed regarding the vial pressurization, heating temperatures, and equilibration times to ensure optimal analysis conditions.
For standards preparation in headspace GC, it's generally recommended to use a solvent that matches the volatility and chemical nature of the analytes of interest. Organic solvents that are volatile and compatible with the GC system, such as methanol or ethanol, are often preferred.
Perform a thorough check of the GC system, focusing on potential leak points such as the injector, detector, and connection points. Use leak detection solutions if necessary.
Ensure that the sample preparation method is optimized for headspace analysis. Review and adjust the headspace GC system settings, such as oven temperature, carrier gas flow rate, and injection volume, to improve the analysis of water-diluted samples.
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