I am currently setting up an analytical method for N-Nitroso Dorzolamide, but I am experiencing a significant drop in peak area values. Has anyone encountered this issue before? How did you resolve it? Please share your experience or suggestions.
We need more information. Are you using LC-MS? Is the signal drop continuous, or does it occur for example only after injecting the sample solution? There are too many unknown variables to provide accurate help.
Thank you for your response. The signal drop occurs continuously after injecting the sample solution. Based on my experience, the area decrease is not severe when analyzing the standard solution. I am using UPLC-MSMS.
It appears that some of the sample matrix remains in the system and is being slowly flushed out, which can lead to signal suppression. If the peak areas increase again after a period without injecting sample solution, this is a clear indication of that issue.
A good way to address this is to perform an intensive column wash, potentially at a higher flow rate to save time. Ensure that the wash includes both an aqueous and an organic component, as the exact cause of the contamination is unknown.
The best solution is to use the correct column for your analysis. However, I understand that many laboratories use the same column for multiple methods, even when it is not ideal for all applications. Additionally, sample cleanup techniques such as SPE can help reduce matrix-related problems.
Regards,
Philipp