Optimization of the atmospheric pressure chemical ionization liquid chromatography mass spectrometry interface

Garcia, D. M.; Huang, S. K.; Stansbury, Wayne F.

doi:10.1016/1044-0305(95)00620-6

Cited by 41 publications

(23 citation statements)

References 24 publications

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“…These analytes formed mainly radical cations in DA-APCI, but protonated molecules in APCI. The result is in agreement with previous reports using APCI, which have shown signal decrease at high flow rates, especially for lower polarity compounds [38,39]. The flow rate dependence in APCI could be explained by the growth of solvent cluster size, which reduces proton transfer between protonated solvent clusters and analytes with low PA. Also, an increased amount of solvent impurities in the source may lead to competition for protons between analytes and the impurities, and decrease the ionization efficiency of the analytes.…”

Section: Effect Of Flow Ratesupporting

confidence: 83%

Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization

Vaikkinen

Kauppila

Kostiainen

2016

J. Am. Soc. Mass Spectrom.

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Abstract. The efficiencies of charge exchange reaction in dopant-assisted atmospheric pressure chemical ionization (DA-APCI) and dopant-assisted atmospheric pressure photoionization (DA-APPI) mass spectrometry (MS) were compared by flow injection analysis. Fourteen individual compounds and a commercial mixture of 16 polycyclic aromatic hydrocarbons were chosen as model analytes to cover a wide range of polarities, gas-phase ionization energies, and proton affinities. Chlorobenzene was used as the dopant, and methanol/water (80/20) as the solvent. In both techniques, analytes formed the same ions (radical cations, protonated molecules, and/or fragments). However, in DA-APCI, the relative efficiency of charge exchange versus proton transfer was lower than in DA-APPI. This is suggested to be because in DA-APCI both dopant and solvent clusters can be ionized, and the formed reagent ions can react with the analytes via competing charge exchange and proton transfer reactions. In DA-APPI, on the other hand, the main reagents are dopant-derived radical cations, which favor ionization of analytes via charge exchange. The efficiency of charge exchange in both DA-APPI and DA-APCI was shown to depend heavily on the solvent flow rate, with best efficiency seen at lowest flow rates studied (0.05 and 0.1 mL/min). Both DA-APCI and DA-APPI showed the radical cation of chlorobenzene at 0.05-0.1 mL/min flow rate, but at increasing flow rate, the abundance of chlorobenzene M +. decreased and reagent ion populations deriving from different gas-phase chemistry were recorded. The formation of these reagent ions explains the decreasing ionization efficiency and the differences in charge exchange between the techniques.

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Section: Effect Of Flow Ratesupporting

confidence: 83%

Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization

Vaikkinen

Kauppila

Kostiainen

2016

J. Am. Soc. Mass Spectrom.

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“…Unlike IS and SS, where the ionization mechanism is mainly based on liquid‐phase processes, APCI is primarily based on gas‐phase chemistry and ionization is achieved by typical reactions like charge transfer, electron capture, and ion‐molecule reactions between a reactant gas plasma and the analyte 2,. 4,, 13 As demonstrated in Fig. 4, this resulted in a different behavior towards changes in eluent composition.…”

Section: Resultsmentioning

confidence: 99%

Influence of the eluent composition on the ionization efficiency for morphine of pneumatically assisted electrospray, atmospheric‐pressure chemical ionization and sonic spray

Dams

Benijts

Günther

et al. 2002

Rapid Comm Mass Spectrometry

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A comparative study of three atmospheric-pressure ionization (API) sources for liquid chromatography/mass spectrometry (LC/MS), namely pneumatically assisted electrospray or ionspray (IS), atmospheric-pressure chemical ionization (APCI), and sonic spray (SS), with respect to the influence of the eluent composition on the ionization of morphine, is presented. The effect of organic modifiers, volatile acids, and buffer systems (with and without pH adjustment) in the LC mobile phase on the ionization efficiency of each interface is described. We conclude that for all three ion sources, the composition of the liquid phase had a serious impact on the ionization of the target compound. For IS and SS, very similar behavior towards the LC eluent was observed. In both cases, an increase in organic modifier resulted in an increase in ionization, while an increasing amount of volatile acid or buffer caused signal suppression. APCI, on the other hand, proved to respond completely differently towards the changes in the eluent. Again, an increased ionization was observed with an increase in organic modifier content but this time also in the presence of mobile phase additives like acids or buffers. Finally, we concluded that APCI proved to be the preferred ion source for the test compound because of its robust character and its direct applicability in traditional LC analysis.

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“…These data lead to the assumption that flow rate effect is compound dependent in APCI. This speculation can be also based on reported positive [36] and negative [37] flow rate effect on APCI for different compounds with different instrumentation. A flow rate of 0.15 mL/min was finally selected, because of the lower sensitivity of DCA at higher flow rates.…”

Section: Optimization Of Lc-apci-ms/ms Methodsmentioning

confidence: 99%

Optimization and Comparison of ESI and APCI LC-MS/MS Methods: A Case Study of Irgarol 1051, Diuron, and their Degradation Products in Environmental Samples

Maragou

Thomaidis

Koupparis

2011

J. Am. Soc. Mass Spectrom.

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A systematic and detailed optimization strategy for the development of atmospheric pressure ionization (API) LC-MS/MS methods for the determination of Irgarol 1051, Diuron, and their degradation products (M1, DCPMU, DCPU, and DCA) in water, sediment, and mussel is described. Experimental design was applied for the optimization of the ion sources parameters.Comparison of ESI and APCI was performed in positive-and negative-ion mode, and the effect of the mobile phase on ionization was studied for both techniques. Special attention was drawn to the ionization of DCA, which presents particular difficulty in API techniques. Satisfactory ionization of this small molecule is achieved only with ESI positive-ion mode using acetonitrile in the mobile phase; the instrumental detection limit is 0.11 ng/mL. Signal suppression was qualitatively estimated by using purified and non-purified samples. The sample preparation for sediments and mussels is direct and simple, comprising only solvent extraction. Mean recoveries ranged from 71% to 110%, and the corresponding (%) RSDs ranged between 4.1 and 14%. The method limits of detection ranged between 0.6 and 3.5 ng/g for sediment and mussel and from 1.3 to 1.8 ng/L for sea water. The method was applied to sea water, marine sediment, and mussels, which were obtained from marinas in Attiki, Greece. Ion ratio confirmation was used for the identification of the compounds.

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Optimization of the atmospheric pressure chemical ionization liquid chromatography mass spectrometry interface

Cited by 41 publications

References 24 publications

Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization

Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization

Influence of the eluent composition on the ionization efficiency for morphine of pneumatically assisted electrospray, atmospheric‐pressure chemical ionization and sonic spray

Optimization and Comparison of ESI and APCI LC-MS/MS Methods: A Case Study of Irgarol 1051, Diuron, and their Degradation Products in Environmental Samples

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