Is it really a single peak or is there any sort of isotopic pattern around it?

Jürgen Weippert thank you for your help. I have attached two screenshots here which may help. I will really appreciate your thoughts here. :)

Looks like the mass on Nylon

@david what do you think could be the possible source for this? I prepared the samples as in the previous batch where I was not seeing this ion.

If it's Nylon, is it possible you used a new batch of starting material and the packaging was contaminated? I mean, it wouldn't be the first time a packaging worker creates weirdness: https://en.wikipedia.org/wiki/Phantom_of_Heilbronn

@Ali - I'm guessing you say you followed the exact same protocol - but was it exactly the same materials from the same source?

Hi,

Inject system blank and reagent blank respectively. Depending on your sample matrix (aqueous or organic) inject blank directly without any sample prep and examine the spectrum if it is obtained then you should divide the LC and MS parts for identifying. But if it is ok, you can prepare a reagent blank and inject it. Without your sample matrix, use only the similar composition of your sample (aqueous or organic) and prepare it according to the established sample prep. protocol. Investigate whether the peak is there or not. If you detect interference then it would be easy to estimate where it can be coming from by eliminating the sample prep. steps and/or equipment one by one.

Good luck.

Hi Ali,

the mass 453.34 (exact mass: 453.34353) seems to be an [M+H]+ ion with the elemental composition C24H44N4O4. Possible source could be Nylon (Cyclic oligomer of polyamide 66, (adipic acid/hexylmethylene diamine condensation). See here: Tran, J.C.; Doucette, A.A. J. Am. Soc. Mass Spectrom., 17 (2006) 652.

Regards

Markus

Hi Ali,

if you send me an e-mail to my adress ([email protected]) I will send you a very comprehensive Excel sheet with common interferences and contaminants in mass spectrometry.

Best regards

Markus