Use of non-volatile ion-pairing agents for liquid chromatographic-mass spectrometric analyses with a moving-belt interface

Escott, Richard; McDowell, Phillip G.; Porter, Neil

doi:10.1016/s0021-9673(01)88456-9

Cited by 20 publications

(8 citation statements)

References 17 publications

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“…They protect only the MS part of the system, but the HPLC system has to be carefully cleaned anyway after the use of alkylamines. A micro‐membrane suppressor placed between a UV and a particle beam electron ionization mass spectrometer can be used instead, as described by Escott et al 26 for the analysis of both cationic and anionic species with ion‐pairing HPLC/MS. Ion‐exchange HPLC on aminopropyl columns can also be used for the separation of sulphonic acids,7 but very high concentrations of mobile phase additives are required (up to 120 mmol l −1 of ammonium acetate and 762 mmol l −1 of acetic acid in 65% aqueous acetonitrile), which negatively affects the ESI signal.…”

Section: Introductionmentioning

confidence: 99%

Effects of ion‐pairing reagents on the electrospray signal suppression of sulphonated dyes and intermediates

et al. 2004

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High-performance liquid chromatography/mass spectrometry (HPLC/MS) analysis of anionic species such as sulphonic acid dyes and intermediates requires volatile ion-pairing mobile phase additives. Six di- and trialkylammonium acetates were compared with tetraalkylammonium salts and ammonium acetate in the concentration range 0-20 mmol l(-1) as mobile phase additives for HPLC/MS of polysulphonated compounds. The effects of the structure and concentration of the ion-pairing reagents on the electrospray response of mono-, di- and tetrasulphonic aromatic acids and acid dyes were studied in detail. Further, five different mass analysers and instrument geometries were compared. A higher signal decrease is observed with linear geometry instruments in comparison to orthogonal or even Z-spray geometry mass spectrometers. The concentration of mobile phase additives has a significant influence on the abundance ratios of multiply charged ions in the mass spectra of polysulphonated compounds. The competing ions of sulphonic acids may also cause significant signal suppression.

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Section: Introductionmentioning

confidence: 99%

Effects of ion‐pairing reagents on the electrospray signal suppression of sulphonated dyes and intermediates

et al. 2004

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“…The use of column switching techniques have been employed to switch from an MS-incompatible mobile phase in the first column to optimum MS conditions (Edholm et af., 1988, van der Greef et al, 1988. The removal of nonvolatile ion-pairing agents by means of a post-column micromembrane suppressor system has been used by Escott et al (1991). Verheij et at.…”

Section: Important Parameters Of Lc-ms Interfacesmentioning

confidence: 99%

Liquid chromatography coupled with mass spectrometry in the analysis of alkaloids

Verpoorte

Niessen

1994

Phytochemical Analysis

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“…6 The reversed-phase high performance liquid chromatography (RP-HPLC) is a promising alternative to SFM/SSM, having such advantages as high throughput, insensitivity to impurities and broad lipophilicity range. [11][12][13] However, for ionizable acidic or basic compounds, the dissociation is completely suppressed only when the pH of mobile phase was adjusted to at least 2 pH units lower or higher than pK a of the solute, which means that very strong acidity or alkalinity of mobile phase is required for those compounds with extreme pK a values, decreasing the life of chromatographic columns as well as apparatus. This straight relationship between log K ow and log k w is also known as Collander equation.…”

Section: Introductionmentioning

confidence: 99%

“…In fact, most environmental and biomedical molecules are more or less dissociated, therefore, buffers including acids and bases are added into the mobile phases to suppress the dissociation of compounds with acid-base properties, which results in improved chromatographic retention and peak shape in RP-HPLC. [11][12][13] However, for ionizable acidic or basic compounds, the dissociation is completely suppressed only when the pH of mobile phase was adjusted to at least 2 pH units lower or higher than pK a of the solute, which means that very strong acidity or alkalinity of mobile phase is required for those compounds with extreme pK a values, decreasing the life of chromatographic columns as well as apparatus. The apparent n-octanol/water partition coefficient (K 00 ow ) has been proposed to correct K ow so as to describe the lipophilicity of ionizable solutes more precisely.…”

Section: Introductionmentioning

confidence: 99%

Influence of n-octanol in mobile phase on QSRRs of lipophilicity and retention mechanism of acidic and basic compounds in RP-HPLC

Han

Liang

et al. 2015

RSC Adv.

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The influence of n-octanol additive agent on the retention behavior, the uniformity of the retention mechanism, as well as the quantitative structure-retention relationships (QSRRs) of weak acidic and basic compounds on reversed-phase high performance liquid chromatography (RP-HPLC) was systematically discussed in this paper, especially for the QSRRs of logarithm of apparent n-octanol/water partition coefficient (log K 00 ow ) and logarithm of retention factor extrapolated to neat aqueous mobile phase (log k w(o) ), which have not been discussed in other studies to date. For this purpose, the aqueous fraction of mobile phase was saturated with n-octanol and 0.25% (v/v) n-octanol was added into organic modifier. Eleven substituted benzoic acids, as well as fifteen anilines or pyridines were selected to establish QSRR models by using different types of ion-suppressors. The results indicated that the roles of n-octanol were different in various systems. For acids compounds, if perchloric acid (strong acid) acts as an ion-pair agent, the silanophilic interaction between solutes and residual silanol groups of alkyl-silica stationary phase can be ignored, and n-octanol/water partition and chromatographic process are homoenergetic. In this case, n-octanol acts only as organic modifier. However, if acetic acid (weak acid) or phosphoric acid/potassium dihydrogen phosphate (buffer salt) were used as the ion-suppressor, noctanol is not only an organic modifier, but also a masking agent of free silanols. For weak bases, if ammonium chloride-ammonia was employed as the ion-suppressor, the addition of n-octanol will make QSRRs correlation significantly worse. Therefore, for studying on QSRRs of lipophilicity and retention behavior of acidic and basic compounds, n-octanol is only recommended for acidic system, and strong monoprotic acids, e.g., perchloric acid, are recommended as the ion-suppressors.

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Use of non-volatile ion-pairing agents for liquid chromatographic-mass spectrometric analyses with a moving-belt interface

Cited by 20 publications

References 17 publications

Effects of ion‐pairing reagents on the electrospray signal suppression of sulphonated dyes and intermediates

Effects of ion‐pairing reagents on the electrospray signal suppression of sulphonated dyes and intermediates

Liquid chromatography coupled with mass spectrometry in the analysis of alkaloids

Influence of n-octanol in mobile phase on QSRRs of lipophilicity and retention mechanism of acidic and basic compounds in RP-HPLC

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