It seems that there are explanations for the ion suppression in the open literature. But I hardly get an explanation for ion enhancement. Can some one, please, share me an information on this?
Are you referring to "doping" or adduct formation in LC-MS analysis? *Plenty of free literature and information available on this topic, just try a keyword search on the web. I have linked an article I use in my training classes, "Adduct formation in LC-MS Analysis (esp. ESI)", to this post which provides a practical introduction to the technique.
https://hplctips.blogspot.com/2011/12/adduct-formation-in-lc-ms-analysis-esp.html
Matrix usually suppresses or interferes with the signal. This is in contrast to your previous question. What are you trying to ask? Is this a homework assignment or class question? You may want to discuss with your instructor or others local to you with more experience first.
Something in the sample matrix is altering the gas phase chemistry (most likely acid/base) of the droplet to allow more complete ionization of the target molecules. The best way to handle it is to use isotope dilution with an isotopically labeled standard of your analyte.
Hi Hailemariam
It could be your mobile phase increasing the solvent concentration during a gradient run. As the solvent increases the evaporation of the mobile phase is enhanced resulting in better ionisation. The other possibility is better ionisation as the relative concentration of additives (formate, ammonium buffer) change, again due to gradients of mobile phases.
The question is how do you perceive that you have signal enhancement? A sample compared to a standard or relative to your tuning mix? Or have you changed your chromatographic conditions?
@ Duncan...Is it not that we use different approaches to calculate a matrix effect? When the value is positive or above hundred, we say we have signal enhancement. If the value is less than hundred (or negative), we say we have ion suppression (Signal suppression). My interest is to know the mechanism of signal enhancement by a matrix from a sample.
Typically "signal enhancement" is used in reference to an analyte in matrix i.e. a sample vs. the same analyte out of matrix, i.e. a standard. It could also be applied a known amount of an analyte with an enhance signal in one matrix vs. another. A simplistic way to think of the "spray plume" is a pot of chemicals competing for charge energy. Your analyte might have a greater affinity to accept or loose a charge in one matrix vs the other. I hope this helps
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