Small Host–Guest Systems in the Gas Phase: Tartaric Acid as a Host for both Anionic and Cationic Guests in the Atmospheric Pressure Chemical Ionization Source of Ion Mobility Spectrometry

Valadbeigi, Younes; Azizmohammadi, Sima; Ilbeigi, Vahideh

doi:10.1021/acs.jpca.0c00118

Cited by 12 publications

(10 citation statements)

References 58 publications

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“…Hence, (CA-H) − is not hydrated in the temperature range of 100–200 °C (Figure S8-c). Recently, we observed the same trend for hydration of protonated tartaric acid and tartrate anion in gas phase Figure S11 shows the optimized structures of hydrated halides (H 2 O) 1–4 Cl – , (H 2 O) 1–4 Br – , and (H 2 O) 1–4 I – in gas phase.…”

Section: Resultssupporting

confidence: 72%

A Novel Application of Dopants in Ion Mobility Spectrometry: Suppression of Fragment Ions of Citric Acid

2020

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Ion mobility spectra of citric acid (CA) are complex, and several peaks are observed for CA and its fragments in both the positive and negative modes. Using DFT calculations, we found that the fragments are both less acidic and less basic than CA in gas phase. Hence, we used a strong base, NH3, in positive mode to produce NH4 + as an alternative reactant ion (RI) and prevent protonation of the fragments. In the presence of NH4 +, only one peak for CA was observed because of its higher proton affinity (873 kJ mol–1) compared to NH3 (854 kJ mol–1). In the negative mode, CHCl3, CHBr3, and CHI3 were used as dopant gases to produce Cl–, Br–, and I– as RIs. These halides have less basicity than the common RIs in negative mode (NO2 –, NO3 –, O2 –) and selectively deprotonated CA in the presence of its fragments. Hence, using dopants with appropriate basicity, we could suppress the fragment peaks and obtain a plain IMS spectrum for CA containing only one peak in both the positive and negative modes. Using NH3 and CHCl3 dopants, the amount of CA in fresh lemon juice was determined as 39.5–42 g L–1 by direct injection without any purification. The effect of hydration of the reactant and product ions on the ionization mechanism in both negative and positive modes was investigated theoretically.

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Section: Resultssupporting

confidence: 72%

A Novel Application of Dopants in Ion Mobility Spectrometry: Suppression of Fragment Ions of Citric Acid

2020

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“…Morphine has two OH groups acting as hydrogen‐bond donors that enable morphine to act as an anion receptor 35,36 . Hence, we investigated Cl − attachment to morphine which occurs more efficiently at lower temperatures 13 . Figure 3 shows the ion mobility spectra of morphine and codeine in the presence of chloroform dopant (Cl − as the main reactant ion) at different temperatures.…”

Section: Resultsmentioning

confidence: 99%

“…Ion mobility spectrometry (IMS) is a rapid and simple technique used for the analysis of a wide range of compounds 1–7 and investigation of ion formation in the gas phase 8–13 . In drift tube ion mobility spectrometers, ions are formed in the ion source, they move toward the detector under an electric field and are separated based on the difference in their mobility ( K o ) 14,15 .…”

Section: Introductionmentioning

confidence: 99%

Using gas‐phase chloride attachment for selective detection of morphine in a morphine/codeine mixture by ion mobility spectrometry

Valadbeigi

Ilbeigi

2021

Rapid Comm Mass Spectrometry

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Rationale Morphine and codeine are two important compounds of the opiate family that have vast applications in medicine. Several techniques have been reported for the determination of these opiates. Although ion mobility spectrometry (IMS) in positive ion mode can be applied for detection of both morphine and codeine, this technique on its own cannot detect a mixture of these two compounds because of the overlapping of their peaks. Methods An IMS instrument equipped with a corona discharge ion source operating in negative ion mode was used for the detection of anionic clusters of morphine and codeine. In normal negative ion mode, NOx−, CO3−, and On− act as the main reactant ions (RIs) which can deprotonate the analytes. We also used chloroform as a dopant to produce Cl− as an alternative RI. Results Morphine has a phenolic and an alcoholic OH group, while codeine bears only an alcoholic OH group. Because the phenolic OH group is more acidic, only morphine is deprotonated in negative ion mode in a morphine/codeine mixture. Furthermore, since morphine has two OH groups that can act as hydrogen‐bond donors, it acts as an anion receptor. Hence, in the presence of chloroform where Cl− acts as the RI, morphine traps the Cl− anion to form a morphine–Cl− (Mor.Cl−) adduct ion, while because of its structure codeine does not have this capability. Conclusions Using the difference in the structures of morphine and codeine, two ionization methods were proposed for selective detection of morphine. Morphine is more acidic than codeine and has greater anion‐receiving capability than codeine. Hence, it can both be deprotonated and form a adduct anion with Cl−. The Cl− attachment method is recommended for measurements at ambient temperature.

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“…Hence, formation of these hydronium clusters diminishes water elimination from the protonated morphine and codeine and consequently reduces their fragmentation. In the solid samples, because only the compounds are vaporized and entered to the ionization region, the concentration of water molecules is very low (30–50 ppm), and the protonated molecules are not hydrated (or are less hydrated) 38,46 . Hence, for solid samples, the fragmentation due to water elimination from the protonated molecules is enhanced, and more intense peaks for the carbocation fragments (M2 and C2) are observed.…”

Section: Resultsmentioning

confidence: 99%

“…In this condition, hydronium ion, H 3 O + , is the main reactant ion (RI). To produce NH 4 + as another RI, the headspace of ammonium carbonate was injected to ion source as NH 3 dopant 38,39 by dopant gas (zero air) with flow rate of 10 ml min −1 . The samples were injected as both solid and aqueous solutions (100 ppm).…”

Section: Experimental Instrumentationmentioning

confidence: 99%

Mechanism of atmospheric pressure chemical ionization of morphine, codeine, and thebaine in corona discharge–ion mobility spectrometry: Protonation, ammonium attachment, and carbocation formation

2020

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Atmospheric pressure chemical ionizations (APCIs) of morphine, codeine, and thebaine were studied in a corona discharge ion source using ion mobility spectrometry (IMS) at temperature range of 100 C-200 C. Density functional theory (DFT) at the B3LYP/6-311++G(d,p) and M062X/6-311++G(d,p) levels of theory were used to interpret the experimental data. It was found that in the presence of H 3 O + as reactant ion (RI), ionization of morphine and codeine proceeds via both the protonation and carbocation formation, whereas thebaine participates only in protonation. Carbocation formation (fragmentation) was diminished with decrease in the temperature. At lower temperatures, proton-bound dimers of the compounds were also formed. Ammonia was used as a dopant to produce NH 4 + as an alternative RI. In the presence of NH 4 + , proton transfer from ammonium ion to morphine, codeine, and thebaine was the dominant mechanism of ionization. However, small amount of ammonium attachment was also observed. The theoretical calculations showed that nitrogen atom of the molecules is the most favorable proton acceptor site while the oxygen atoms participate in ammonium attachment. Furthermore, formation of the carbocations is because of the water elimination from the protonated forms of morphine and codeine.

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Small Host–Guest Systems in the Gas Phase: Tartaric Acid as a Host for both Anionic and Cationic Guests in the Atmospheric Pressure Chemical Ionization Source of Ion Mobility Spectrometry

Cited by 12 publications

References 58 publications

A Novel Application of Dopants in Ion Mobility Spectrometry: Suppression of Fragment Ions of Citric Acid

A Novel Application of Dopants in Ion Mobility Spectrometry: Suppression of Fragment Ions of Citric Acid

Using gas‐phase chloride attachment for selective detection of morphine in a morphine/codeine mixture by ion mobility spectrometry

Mechanism of atmospheric pressure chemical ionization of morphine, codeine, and thebaine in corona discharge–ion mobility spectrometry: Protonation, ammonium attachment, and carbocation formation

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