Optimization of the dopant for the trace determination of polycyclic aromatic hydrocarbons by liquid chromatography/dopant-assisted atmospheric-pressure photoionization/mass spectrometry

Itoh, Nobuyasu; Aoyagi, Yoshie; Yarita, Takashi

doi:10.1016/j.chroma.2006.08.091

Cited by 89 publications

(73 citation statements)

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“…Anisole, however, has a relatively low IE (8.20 eV), restricting its applicability. Mixtures of anisole and toluene have been utilized by Itoh et al as dopants to promote charge exchange ionization under reversed-phase conditions, in the analysis of the 16 polycyclic aromatic hydrocarbons (PAHs) identified by the US EPA as priority pollutants [12]. In this case, multicomponent dopants were examined after initial experiments established that, even if imperfect, toluene was still the best dopant for the early-eluting, high-IE PAHs naphthalene (8.14 eV) and acenaphthylene (8.12 eV), while anisole was best for the others.…”

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confidence: 99%

Comparison of dopants for charge exchange ionization of nonpolar polycyclic aromatic hydrocarbons with reversed-phase LC-APPI-MS

Smith

Robb

Blades

2009

J. Am. Soc. Mass Spectrom.

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Atmospheric pressure photoionization (APPI) is capable of ionizing nonpolar compounds in LC/MS, through charge exchange reactions following photoionization of a dopant. Recently, several novel dopants-chlorobenzene, bromobenzene, 2,4-difluoroanisole, and 3-(trifluoromethyl)anisole-have been identified as having properties making them wellsuited to serve as dopants for charge exchange ionization under reversed-phase LC conditions. Here, we report the results of experiments comparing their effectiveness to that of established dopants-toluene, anisole, and a toluene/anisole mixture, for the charge exchange ionization of model nonpolar compounds-the 16 polycyclic aromatic hydrocarbons (PAHs) identified by the US EPA as priority pollutants-when using a conventional reversed-phase LC method. Chloro-and bromobenzene were found to be much more effective than toluene for all the PAHs, due to the relatively low reactivity of their photoions with the solvent. Their overall performance was also better than that of anisole, due to anisole's ineffectiveness toward higher-IE compounds. Further, the experiments revealed that anisole's performance for higher-IE compounds can be dramatically improved by introducing it as a dilute solution in toluene, rather than neat. The two fluoroanisoles provided the highest overall sensitivity, by a slim margin, when introduced as dilute solutions in either chloro-or bromobenzene. With APPI, analyte ionization is mostly due to ionmolecule reactions following photoionization of a primary reagent, typically a dopant [4]. Analyte ionization can occur in positive mode through either proton transfer or charge exchange (electron-transfer) reaction pathways. This article regards the ionization of nonpolar, low proton affinity compounds via charge exchange with dopant radical cations.In APPI, for charge exchange ionization to occur the dopant's ionization energy (IE) must be greater than that of the analyte and to be efficient its radical cations must not be consumed through reactions with the solvent, its own neutrals, or impurities. Toluene was the first dopant to be used for charge exchange ionization in APPI [1], and it has a relatively high IE (8.83 eV), making it suitable for a wide range of analytes (all IE values are from reference [5]). In practice, however, toluene is only an efficient charge exchange dopant under normal-phase [6,7] and/or low-flow conditions[8] because its radical cations are rapidly consumed in reactions with methanol and acetonitrile at conventional LC flow rates [6, 9, 10]. Some other dopant is then required for efficient charge exchange ionization with reversed-phase LC methods. The usual alternative to toluene for promoting charge exchange ionization is anisole, whose photoions are stable in the presence of methanol and acetonitrile [11]. Anisole, however, has a relatively low IE (8.20 eV), restricting its applicability. Mixtures of anisole and toluene have been utilized by Itoh et al. as dopants to promote charge exchange ionization under reversed-phase conditions, i...

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confidence: 99%

Comparison of dopants for charge exchange ionization of nonpolar polycyclic aromatic hydrocarbons with reversed-phase LC-APPI-MS

Smith

Robb

Blades

2009

J. Am. Soc. Mass Spectrom.

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“…e analytes are ionized via charge exchange and proton transfer reactions with the primary ions. [23][24][25] Since an electrospray ionization (ESI) plume contains numerous charged species (e.g., charged solvent droplets, solvent ions, solvent cluster ions, H 3 O + , and H + ), analytes are ionized through IMRs with these charged species in the ESI plume. Laser desorption, pyrolysis, nebulization, and thermal desorption are used to generate analytes from solid or liquid samples.…”

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confidence: 99%

Desorption Flame-Induced Atmospheric Pressure Chemical Ionization Mass Spectrometry for Rapid Real-World Sample Analysis

2017

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Flame-induced atmospheric pressure chemical ionization (FAPCI) is a solvent and high voltage-free APCI technique. It uses a ame to produce charged species that reacts with analytes for ionization, and generates intact molecular ions from organic compounds with minimal fragmentation. In this study, desorption FAPCI/MS was developed to rapidly characterize thermally stable organic compounds in liquid, cream, and solid states. Liquid samples were introduced into the ion source through a heated nebulizer, and the analytes formed in the heated nebulizer reacted with charged species in the source. For cream and solid sample analysis, the samples were positioned near the ame of the FAPCI source for thermal desorption and ionization. is approach provided a useful method to directly characterize samples with minimal pretreatment. Standards and real-world samples, such as drug tablets, ointment, and toy were analyzed to demonstrate the capability of desorption FAPCI/MS for rapid organic compound analysis.

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“…(Yamamoto et al, 2006;Viglino et al, 2008). Atmospheric pressure photoionization is the ionization of choice for PAHs and showed results comparable to gas chromatography mass spectrometry (Itoh et al, 2006;Cai et al, 2009). Indeed, APPI not only gives superior performance on nonpolar compounds but also works great for analytes which are out of the reach of ESI and APCI.…”

Section: Ionization Techniquesmentioning

confidence: 92%

“…The application and principle of APPI have been reviewed and the rapidly growing number of publications in this area clearly demonstrates the advantages of APPI (Hanold et al, 2004;Bos et al, 2006). Atmospheric pressure photoionization has proven to be a valuable tool for analytes, which are poorly or not ionized by ESI and APCI or in the presence of complex analytical condition (Itoh et al, 2006;Yamamoto et al, 2006;Viglino et al, 2008;Cai et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Assessment of the Occurrence and Potential Effects of Pharmaceuticals and Personal Care Products in South Florida Waters and Sediments

Wang¹

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All rights reserved.iv DEDICATION It is not easy to start pursuing a Ph.D and it becomes even harder towards the end. It is a kind of job that makes me start to question myself; it is a period of time in my life that I am desperate to call for help. But I am indeed blessed.I dedicate this dissertation to my parents, without their understanding and support and most of all love, it is impossible for me to walk so far on my way of pursuing my dream. They not only gave me life but also taught me how to become a better person.I dedicate this dissertation to my husband, without him, I will never know the colorful and beautiful part of life. He lets me feel peaceful and powerful when I face difficulties. An ASE-SPE-GC-MS method was developed and applied to the analysis of the sediment and soil area where reclaimed water was used for irrigation. Most analytes were below detection limits, even though some of analytes were detected in the reclaimed water at relatively high concentrations corroborating the fact that PPCPs do not significantly partition to mineral phases.

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Optimization of the dopant for the trace determination of polycyclic aromatic hydrocarbons by liquid chromatography/dopant-assisted atmospheric-pressure photoionization/mass spectrometry

Cited by 89 publications

References 14 publications

Comparison of dopants for charge exchange ionization of nonpolar polycyclic aromatic hydrocarbons with reversed-phase LC-APPI-MS

Comparison of dopants for charge exchange ionization of nonpolar polycyclic aromatic hydrocarbons with reversed-phase LC-APPI-MS

Desorption Flame-Induced Atmospheric Pressure Chemical Ionization Mass Spectrometry for Rapid Real-World Sample Analysis

Assessment of the Occurrence and Potential Effects of Pharmaceuticals and Personal Care Products in South Florida Waters and Sediments

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