Electrospray ionization is very soft, and in an MS analysis will not fragment the molecule. The results you get will depend on the type of ionization you are applying, positive or negative, so you will get m/z values of [M+1] or [M-1].

Mr. Soonho,

ESI-MS is a powerful ionization method, among other mass spectrometric methods, namely, because of it is very soft as mrs/miss Barragan has highlighted in her posting.

Due to, its soft-ionization nature the ESI-MS is highly informative approach from the perspective of the qualitative, quantitative and 3D structural analyses. The ionization efficiency and analyte fragment paths depend on experimental conditions. In this context you could try an analysis in presence of alkali metal ions, for example. Very frequently, analytes stabilize NH4+-adducts, as well.

Please, concentrate on the following very useful references [1,2]. They detail on ionization capability of ESI-MS, in addition to, a set of molecular and experimental factors affecting on the fragment paths of analytes under ESI-MS conditions.

[1] R. Cole, Electrospray Ionization Mass Spectrometry: Fundamentals, Instrumentation, and Applications, John Wiley & Sons; 1. Auflage (1997) pp. 1 - 600; ISBN-10 : 0471145645

[2] R. Cole, Electrospray and MALDI Mass Spectrometry: Fundamentals, Instrumentation, Practicalities, and Biological Applications, 2nd Edition, ISBN: 978-0-471-74107-7 (2010), pp. 1 - 896.

Gabriela S. Barragan-Zarate Bojidarka B. Ivanova Thank you so much for your reply.

Actually, when I did an analysis, I set collision energy(CE) 35 eV.

So, even if I set the CE during the MS mode, it didn't affect the result?

And, I directly inject the sample to micrOTOF-Q III using a syringe pump without HPLC.

And, is there no possibility to be broken by other factors such as drying gas or gas temperature?...

Mr. Soonho,

The ionization efficiency does not depend on, straightforwardly from the applied voltage to the ion source. This issue is debatable, currently. So that, try to carry out a correlative analysis among molecular structure of the analyte, its physical properties and the experimental conditions, respectively. The rote of the molecular factors affecting on the ionization efficiency is far from well understood, as well.

You could pay attention to our word [1], where we have made such effort, developing our theoretical kinetic concept, which has been applied to CID-MS spectra of analytes obtained under different voltages. The ionization efficiency, however, of these analytes depends on the voltage.

Therefore, any conclusions on this issue made on the base on a statistically nonrepresentative set of analytes are far from reliable.

Journal of Molecular Structure, 1149 (2017) 243-256

Quantitative collision induced mass spectrometry of substituted piperazines – A correlative analysis between theory and experiment

Bojidarka Ivanova, Michael Spiteller

Bojidarka B. Ivanova Thank you so much for your help.

I think my analysis case showed the fragment...

I analyzed only one material for basic experiment. However, there were 3 molecules such as M+H, 2M+H, and M(other one). The other one is well fitted with fragment ion.

So, I think the fragment ion can be also generated in the MS mode with collision energy...

Mr. Soonho,

Your data assume a ion-radical mechanism of ion formation.

Please, consider work [1].

[1] Radical Cations in Electrospray Mass Spectrometry: Formation of Open‐Shell Species, Examination of the Fragmentation Behaviour in ESI‐MSn and Reaction Mechanism Studies by Detection of Transient Radical Cations

Mathias Schaefer, Miriam Drayss, Andreas Springer, Philipp Zacharias, Klaus Meerholz, Volume 2007, (2007) 5162-5174.

Bojidarka B. Ivanova Thank you so much for your consideration!

I'm so sorry to bother you.. Can I ask some more?..

(1) Actually, I cant see the reference [1] on the web...

I checked already but it couldn't see even in google scholar...

Can I see that? or, is there other papers that are similar to that book?..

(2) Is fragment ion different from ion radical?...

Mr. Soonho,

There is useful to carry out literature research by name via [www.scopus.com]: The name of the author is R.(B.) Cole.

However, please, bear in mind that there are more than one authors R. Cole. Thus, you should look at author: Richard B. Cole (Faculté des Sciences et Ingénierie Sorbonne Université, France.) He has significant contributions to understand the mass spectrometric phenomena under ESI-MS conditions.

Toward, your second question: The fragment ion is different from ion radical. In the latter case, there is a lack of cleavage of covalent bond (loss of molecular fragment.) More detail, you shall find in the works by R. Cole, as I have written above.

Kim Soonho: Your questions are very basic in nature and you will find that the answers to your question are easier to understand after you take the time to learn some of the basic ESI principles and how your specific MS (ESI) system operates.

In addition to many of the classic texts on the topic (Try GOOGLE for suggestions), please contact someone local who has professional experience in using this specific MS instrument who can explain to you how to better use the system. You will save so much time and learn faster using this method (I professionally train scientists in how to use these instruments for accurate sample analysis and IMO, on-site, in-person training, on their own system/software, is the most efficient method to provide practical training in the least amount of time).

• The collision energy that you are referencing is the supplemental instrument energy 'feature' used in the cell (CID) that can be used to provide additional fragmentation of the ions produced in the MS. The energy level needed must be determined experimentally, then optimized (Or varied to produce different levels of controlled fragmentation) for the sample. Try high levels at first, then decrease the collision energy. This feature is very useful AFTER optimization of the MS conditions and settings and may provide for additional fragmentation for more qualitative peak analysis. *Depending on the MS settings chosen, mode selected, (adducts and/or doping agents used, etc) and the sample/structure present, additional fragmentation may or may NOT be observed. Remember, MS instruments are just one of many available tools and do not always "SEE" everything present. They are NOT Universal Detectors at all and are limited in their capabilities. This is why we scientists do not use them alone, but in combination with other orthogonal techniques to make ID's or draw conclusions.

All of this requires that you first be experienced in how to use the MS system and then the optional CID feature to adjust the energy used. Proper training in how to use these types of advanced analytical instruments often takes years to achieve a basic level of proficiency so we strongly suggest you contact the local professional who has years of method development and MS optimization experience with the specific MS (ESI) instrument that you have at your school for assistance. Without such training or professional experience, the MS system will continue to output data, but it will probably be invalid or of poor quality (As it is well know in this industry by professionals who use these instruments, the data that is output from most any MS system is of no value unless the system has been set-up and optimized with a proper method for the specific sample(s) under analysis).

Bojidarka B. Ivanova Thank you for reply.

Yes. I will check the literature! Thank you so much for your time...

Lastly, I want to ask one thing more... I'm so sorry to bother you..

Then, in case of radical ion, this radical ion is just from the [parent molecule]+?

I asked that for example, m/z[200] -> m/z[150]+ + m/z[50]+ can't occur?...(150 is M+H state)

William Letter Oh thank you so much for your advice..

I'm a graduate student and I feel some difficult to operate ESI-MS alone because there is no expert person... So I'm using it with checking the some papers...

Mr. Soonho,

The term 'parent ion' within the framework of single MS operation mode, meaning, MS1, refers to ion of the initial analyte in solution. The ion-radical, therefore, is a charged radical state of your initial analyte.

For example, there is an analyte in solution: Adenine. Its elemental composition is C5H5N5 and MW = 135.13. If there is ion-radical, then there is a MS peak at m/z 135 or there is [C5H5N5]cation-radical. The protonated analyte should exhibit peak at m/z 136. Its elemental composition should be [C5H6N5]+.

An additional comment on:

RG does not represent an University.

It is forum for exchange of knowledge among researchers worldwide allowing to improve the quality of the Higher Education worldwide, thus giving chance for an almost competitive development of all nations worldwide, including the standard and the quality of the life to any individual, despite, his, respectively, her nation, ethnicity, race, religion, gender, et cetera. This is the purpose of any publication containing scientific innovation, as well.

In this context, noone of us do not receive salary for online education via RG.

I should only mention you that, for example, the salary of a Rector at a University at Germany is higher than 30 000 euro per month. This means that as a teacher at a Higher Educational Institution (the Rectors are from the academic personal compulsory), herein, such individual assimilates within the framework of two consecutive mandates at about 2.8 milion euro brutto, personally. According to the standard of this Country, this represents a dramatically high personal income for a teacher at a University. The average salary, herein, is at about 2000-3000 euro pro person pro month. (At about 97 % of the Universities, herein, are public.)

I do not know how many is this income pro academic personal at your University, but you are able to understand, I hope, that as a graduate student you should request from your professors, respectively, Rector staff, to care about the quality of your Higher Education and professional qualification. They receive salaries for this work.

My latter comment on means that I should not answer to your personal questions to me, further, if these questions cover textbook knowledge of mass spectrometry.

The professors and the administration of your University are obligate to ensure literature, inclusing textbooks, monographs, access to references online, et cetera. They are compulsory, in order to increase the quality of your education and the education of other students and PhD students at your University.

Useful textbook on mass spectrometry (basic knowledge) is the following:

J. Gross, Mass spectrometry, Springer Verlag, 2017, ISBN: 978-3-319-54397-0, pp. 1 - 1148.

[https://www.buecher.de/shop/allgemeine-biochemie/mass-spectrometry/gross-juergen-h/products_products/detail/prod_id/47494466/]

Optimized CE in MS reduce the noise.

Kindly Check..

https://www.hindawi.com/journals/ijac/2012/282574/