****************************************************************************** From: David Sparkman Date: Fri, 26 Jun 1998 13:27:27 -0400 Subject: "Self-CI" What's its origin Organization: * I am looking for the orgin of the term "Self-CI" Someplace I got the idea that Burnaby Munson and Frank Field had coined the phase in their early CI work, but Burnaby denies that. I think "Self-CI" was originally used to describe charge transfer between a molecular ion formed by electron ionization and molecules of the same analyte when the partial pressure of the analyte reached some abnormally high (for normal EI conditions) level. I nedd a literature citation for this. I know the term predates its use to describe behavior in the internal ionization quadrupole ion trap. Second subject, Sometime ago someone wrote asking for a citation to a statement made by Aston that "... there would be no more need for mass spectrometry once all the masses of the various isotopes of the elements had been determined." Was there a refence for this statement ever cited? If so, what was it? Regards; David O. David Sparkman Consultant-At-Large Phone: 1-925-754-5003 ****************************************************************************** From: ijames@netaxs.com (Carl Ijames) Date: 26 Jun 1998 23:09:29 GMT Subject: Re: "Self-CI" What's its orgin Organization: newsread.com ISP News Reading Service The earliest mention of self-ci that I'm aware of is a paper by Sahba Ghaderi, et. al., "Chemical Ionization in Fourier Transform Mass Spectrometry", Anal. Chem., 1981, 53, 428-437. On page 433 they say "This method, which we call "self-CI", works particularly ...", which implies that they coined the name. -- Regards, Carl Ijames ijames@netaxs.com ****************************************************************************** From: gal@unice.fr (J.-F. Gal) Date: Sat, 27 Jun 1998 16:43:59 +0000 Subject: A comment about "Self-CI" Organization: * Dear David, I have used this term several times without knowing its origin, for describing "self protonation" in ICR, a field where I first hear it. In fact charge exchange is rarely encountered in trapping method (ITMS, FT-ICR MS). More often proton transfer is observed, leading to (MH+) ion. The term "self CI" is therefore mostly used for describing the protonation of M by FRAGMENTS of (M+.), and not only by the molecular ion. Therefore it may be a misleading terminology and its use to be discouraged? Cheers, Jean-Francois ------------------------------------- Prof. J.-F. GAL Groupe FT-ICR*GRECFO-Chim. Phys. Org. Fac. des Sciences*Parc Valrose Univ. de Nice-Sophia Antipolis 06108 NICE Cedex 2*FRANCE Tel : (33) (0)4 92 07 61 10 Fax : (33) (0)4 92 07 61 11 E-mail : gal@unice.fr ------------------------------------- ****************************************************************************** From: David Sparkman Date: Sun, 28 Jun 1998 06:21:35 -0400 Subject: Re: Self CI Organization: * In response to Jean-Francois Gal's comments on "Self-CI": I have retrived and read the article cited by Carl Ijames. I agree this is the orgin of the term Self-CI and it is used to mean protonation of analyte molecules by fragment ions resulting from the electron ionization of the same analyte. I think this is a good term and can be expanded to mean the CI of an analyte where the reagent ion is from the an ionized form of the analyte itself; i.e.; a fragment ion or a molecular ion of the analyte that prototonates other molecules of the same analyte OR analyte molecular ions that ionize other molecules of the analyte by charge transfer or addition. What "Self-CI" does not describe is the space charge effect that is observed as a "Christmas Tree" of peaks in digitized data from an internal ionization quadrupole ion trap MS when the partial pressure of the analyte is so high as to result in too many ions in the trap. Regards; David O. David Sparkman Consultant-At-Large Phone: 1-925-754-5003 ****************************************************************************** From: Larry Phillips Date: Mon, 29 Jun 1998 11:32:21 -0400 (EDT) Subject: Origin of the term "self-CI" Organization: * Dear David, On June 26, 1998, you requested assistance in finding the origin of the term "self-CI". Perhaps a quick chronology of some applications noted in the literature may help narrow (or further confuse) the search: "...inter-molecular reactions can occur, and in fact in the case of hexamethylenediamine, a peak occurs at mass 117 (i.e. (p+1)..." J. H. Beynon "Mass Spectrometry and its Applications to Organic Chemistry" Elsevier, Amsterdam, 1960, page 390. "...in-beam electron impact ionization mass spectra of several amino sugars...almost always exhibited the M+1 peak..." M. Ohashi, et. al. Biomed. Mass Spectrom. 5: 578 (1978). "...the ease of chemical ionization by FT-MS, especially the possibility of self-CI (reagentless CI), is also important for identification of the molecules of high mass and for obtaining molecular weight information..." S. Ghaderi, et. al. Proc. Am. Soc. Mass Spectrom. 29: 530 (1981). "...the self-protonation reaction is an ubiquitous reaction for many classes of compounds. Indeed, it is so prevalent that in many cases MH+ ions may be observed ender electron impact conditions unless precautions are taken..." A. G. Harrison, "Chemical Ionization Mass Spectrometry" CRC Press, Inc. Boca Raton, 1983, page 15. "...formation of protonated molecular ions indicates that the [in-beam EIMS] process may partly be one of self chemical ionization..." J. R. Chapman, "Practical Organic Mass Spectrometry" John Wiley and Sons, Chichester, 1985, page 105. And here is an interesting one--- "...the 'ghost spectrum' resulting from self chemical ionisation often serves to confirm the molecular weight..." R. G. Gillis, Organic Mass Spectrom. 9: 359 (1974). This article refers to the self-CI while performing CI---the authors report formation of their 'ghost spectrum' corresponding to protonated dimer, (2M+H)+, while performing normal CI.