Hi all,
I would like to know the robustness of using the intensity signal of detected ions obtained from direct infusion - ICR mass spectrometry.
I am aware of the "ion supression" problem... but do you know of any publication where it is tested? I am interested in comparative analyses, so I really do not need a "real quantification" but a "relative quantification" (comparison of samples from the same or different matrices).
Thanks in advance!!
Hi,
I am not sure of if..but is it possible to 'spike' the samples with a known (standard) amount of a reference ion and then use it for nomalization in different samples..
Thanks Ajay,
I would use the internal standard to know the real concentration of specific molecules in my samples. However, with Direct Infusion there is the ion supression problem, so the intensity of the peaks does not necessary be relatively proportional to the concentration of such ion. Some ions can mask their neighbour ions making their intensities much lower.
With liquid chromatography this issue can be more or less solved. My background is not in analytical chemistry, so I would like to know more opinions (or articles) where researches face this issue with the ICR direct infusion.
Thanks!!
Hi Albers,
in principle the spiking approach is not wrong... if you take some precautions. Take something to spike, that does not interfere with your expected masses (e.g. perfluoro carbonic acids, ect.). Take a spiking agent, which ionizes readily and forms stable ions. Use spiking concentrations that match those of your analytes. Measure a sample of your spiking agent at first, then measure your spiked sample. Compare the results. If the intensities differ not too much, the approach should be feasable.
If you are worried about the robustness of this approach, use multiple spiking agents, representing expected functionalities within your sample, but which can easily be discerend from the sample.
Btw, ion suppression can also be mitigated, if you dilute your sample and increase the flowrate accordingly. The use of a buffer solution also helps to reduce problems with ionization.
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