Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: PP999 on June 07, 2021, 03:03:45 AM
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Hi, I am performing a LC-MS analysis for the quantification of an androgen. The androgen peak is clearly visible at all concentrations that are used for the calibration curve. The only problem is that this peak is also visible in my blank and double blank samples. Also, the intensity of the peak in the blank samples is relatively high.
How do I get rid of the peak in these samples? What could be the problem in this case? Please help. I washed the column many times, but it did not resolve the problem.
Thanks in advance!
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I am not an analytical chemist. However, I would be tempted to look for other possible sources of contamination, such as the solvent. What is you protocol for cleaning the column?
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Your blank solvent is contaminated, perhaps you took the blank sample from a blank solution that you already used to prepare your samples. Always use fresh blank to vial before you prep samples. Other causes may be carryover from the needle, maybe your needle wash needs to be changed. Normally I would inject blanks first, then a std, then the blank again and you will be able to tell if there is carryover from the previous injection. This can be a problem throughout your run if you are adding carryover from the previous samples your results won't be accurate.
If it is your column, maybe your runtime isnt long enough, does your peak return to baseline for long enough before the next injection? Anyway it sounds to me like your column is not the problem.
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Have you run just your solvent?
Could it be that the ion source is contaminated?