Mr. Mabrur,

Both amino acids, respectively, their larger peptidic derivatives as well as the carbohydrates exhibit strongly characteristic MS fragment ions over the whole range of m/z-values from LMW fragment species to macromolecular charged ions. Furthermore, the quantification of these analytes by mass spectrometry is exact (or absolute,) when there is used our innovative stochastic dynamic approach and new our own-authored (mine and my co-author's) formulas for quantification of the MS variable 'intensity.'

In this context, please consider our stochastic dynamic approach shown in reference [1]. The method is tested studying analytes in mixture at pg.(mL)-1 concentration range, showing coefficients of linear correlations between our theory and equations, as well as, experimental MS and chromatographic data /r/ = 0.99997-1.

[1] Steroids, 164 (2020) 108750

Stochastic dynamic mass spectrometric quantification of steroids in mixture — Part II; Bojidarka Ivanova, Michael Spiteller

Owing to the fact, that we have a significant experience with MS analyses of peptides and carbohydrates, you could pay attention to some of our papers devoted to this topic, where we apply namely our innovative concept to determine such analytes in complex muxtures.

Carbohydrates [2]:

[2] Bioorganic Chemistry, 93 (2019) 103308

A mass spectrometric stochastic dynamic diffusion approach to selective quantitative and 3D structural analyses of native cyclodextrins by electrospray ionization and atmospheric pressure chemical ionization methods

Bojidarka Ivanova, Michael Spiteller

Peptides [3]:

[3] Protonation: Properties, Applications and Effects

Bojidarka Ivanova, Michael Spiteller;

Ale Germogen (Editor)

ISBN: 978-1-53614-886-2

NOVA Science Publishers, (2019) New York.

Explicitly, it is important to underline that our method shows remarkable selectivity, so that it is capable of determining exactly even complex mixtures of homologous derivatives of peptides and carbohydrates. For instance, work [2] deals with mixtures of LMW carbohydrates and cyclodextrins, while work [3] deals with MS quantification of homopeptides. This remarkable selectivity is a result from the fact that depending on the type of the mixture and the corresponding derivatives the fragment reactions produce ions showing unique 3D molecular conformations and electronic structures at given experimental conditions. These exactly defining products of fragment chemical processes under MS experimental conditions are characterized by unique free Gibbs energy parameters. Therefore, via our approach there is carried out not only exact quantification, but also exact 3D structural determination of the analytes; furthermore, highly selectively, as aforementioned.

Toward application to our approach to determine analytes 3D structurally, please consider reference [4].

[4] Reviews in Analytical Chemistry, Band 38: Heft 2 (2019)

A stochastic dynamic mass spectrometric diffusion method and its application to 3D structural analysis of the analytes; Bojidarka Ivanova, Michael Spiteller

In other words, there is not needed derivatization as a sample pretreatment step in order to determine selectively analytes in mixture.

Hello Mabrur Mabrur

in general, most derivatives are not infinitely stable, due to this it is generally recommended to do the analysis soon after derivatization. How stable the derivatives are, depends on the derivatized compound and the derivatization reagent (which reagent are you using?). E.g. silylated derivatives of acids are quite prone to hydrolysis while ester derivatives of acids are more stable.

If you want to be on the safe side, I would recommend to do some stability studies with some exemplary derivatives you are analyzing. So you get a clear idea, how long the derivatives are stable.

Please feel free to get back to me, if you have got further questions!

So, in low temp you can store them for sure for few days.

Longer time demands a stability check.

Regards

GB

The storage information should be learned by experience. It depends on your target molecule and different molecules could behave differently after derivatization. alkyl chloroformate derivates, TMS derivates, phthaldehyde derivates, FMOC derivates all can show different stability. In this case, you are looking for metabolomic investigation and it means diverse molecules are in query. Thus analyzing the derivated sample as soon as possible is the best way to keep all elucidative information in the injection vial. After injection, just switch the vial cap to prevent vaporization and test the same vial for consecutive days to validate stability.