Novel Fragmentation Pathways of Anionic Adducts of Steroids Formed by Electrospray Anion Attachment Involving Regioselective Attachment, Regiospecific Decompositions, Charge-Induced Pathways, and Ion–Dipole Complex Intermediates

Rannulu, N. S.; Cole, Richard B.

doi:10.1007/s13361-012-0422-y

Cited by 39 publications

(49 citation statements)

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“…An interesting product ion at m/z 310 was detected and possible forming process was shown in Scheme 1. The processes involve an intermediate formed by the McLafferty-type rearrangement and an ion-dipole complex [18][19][20][21][22][23][24]. Close distance might contribute to the addition reaction between oxo(phenyl)methylium formed by the loss of benzoic acid side chain linked to C1 and pyridine moiety.…”

Section: Resultsmentioning

confidence: 99%

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Analysis of sesquiterpene pyridine alkaloids using ESI–MS/MS: The product ion at m / z 310 formed by an ion–dipole intermediate

Cai

Luo

Zhou

et al. 2015

International Journal of Mass Spectrometry

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Section: Resultsmentioning

confidence: 99%

“…Structural information provided by ESI-MS is obtained by characteristic fragmentation reactions. Interestingly, a product ion can be rationalized by considering the formation of intermediate ion-dipole (ion-neutral) complexes [18][19][20][21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Analysis of sesquiterpene pyridine alkaloids using ESI–MS/MS: The product ion at m / z 310 formed by an ion–dipole intermediate

Cai

Luo

Zhou

et al. 2015

International Journal of Mass Spectrometry

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“…Based on gas-phase basicities, it may therefore be expected that a stable [M -H + NaHCO 3 ] -ion should be observed in the ESI mass spectrum of 22:6 with NaHCO 3 . Indeed, anionic steroid-bicarbonate complexes have previously been observed [46,47], further suggesting that the [M -H + NaHCO 3 ] -ion should be observed in the ESI mass spectrum of 22:6 with NaHCO 3 .…”

Section: Direct Formation Of [M -2h + Na] -Anions By Electrospray Ionmentioning

confidence: 94%

Formation and Fragmentation of Unsaturated Fatty Acid [M – 2H + Na]^– Ions: Stabilized Carbanions for Charge-Directed Fragmentation

Thomas¹,

Kirk

Altvater³

et al. 2013

J. Am. Soc. Mass Spectrom.

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Nette, G. W. (2014). Formation and fragmentation of unsaturated fatty acid [m -2h + na] -ions: stabilized carbanions for charge-directed fragmentation. Journal of the American Society for Mass Spectrometry, 25 (2), 237-247. Formation and fragmentation of unsaturated fatty acid [m -2h + na] -ions: stabilized carbanions for charge-directed fragmentation AbstractFatty acids are long-chain carboxylic acids that readily produce [M -H]-ions upon negative ion electrospray ionization (ESI) and cationic complexes with alkali, alkaline earth, and transition metals in positive ion ESI. In contrast, only one anionic monomeric fatty acid-metal ion complex has been reported in the literature, namely [M -2H + FeIICl]-. In this manuscript, we present two methods to form anionic unsaturated fatty acid-sodium ion complexes (i.e., [M -2H + Na]-). We find that these ions may be generated efficiently by two distinct methods: (1) negative ion ESI of a methanolic solution containing the fatty acid and sodium fluoride forming an [M -H + NaF]-ion. Subsequent collision-induced dissociation (CID) results in the desired [M -2H + Na]-ion via the neutral loss of HF. (2) Direct formation of the [M -2H + Na]-ion by negative ion ESI of a methanolic solution containing the fatty acid and sodium hydroxide or bicarbonate. In addition to deprotonation of the carboxylic acid moiety, formation of [M -2H + Na]-ions requires the removal of a proton from the fatty acid acyl chain. We propose that this deprotonation occurs at the bis-allylic position(s) of polyunsaturated fatty acids resulting in the formation of a resonance-stabilized carbanion. This proposal is supported by ab initio calculations, which reveal that removal of a proton from the bis-allylic position, followed by neutral loss of HX (where X = F-and -OH), is the lowest energy dissociation pathway.

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“…In particular, we sought a way to increase signal intensity of free and halogenated estrogens (pK a ~ 7 -11; ), which have lower ionization efficiencies than conjugated estrogens. Recent work has shown that fluoride ions promote gas-phase deprotonation of neutral steroids (Rannulu and Cole 2012), and ammonium fluoride (NH 4 F) can be used as a mobile phase additive to enhance signal intensity for a variety of metabolites (Yanes, Tautenhahn et al 2011). In our own tests, we found that the addition of ammonium fluoride (1 mM per Yanes et al (2011)) to the aqueous mobile phase (water) increased the response factor of free and brominated estrogens by factors of 20 and 2.6, respectively ( Figure 2).…”

Section: Mobile Phase Composition and Column Temperaturementioning

confidence: 99%

Natural and synthetic estrogens in wastewater treatment plant effluent and the coastal ocean

Griffith¹

2013

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Steroidal estrogens are potent endocrine disrupting chemicals that are naturally excreted by vertebrates (e.g., humans and fish) and can enter natural waters through the discharge of treated and raw sewage. Because estrogens are detrimental to aquatic organisms at picomolar concentrations, many studies have measured so-called "free" estrogen concentrations in wastewater effluents, rivers, and lakes. Yet, to our knowledge, no studies have characterized the broader range of estrogens that includes free, conjugated, and halogenated forms.Conjugated estrogens are important because they can be easily converted to potent free forms by bacteria in wastewater treatment plants and receiving waters. And halogenated estrogens, produced during wastewater disinfection, are only slightly less potent than free estrogens but much more likely to bioaccumulate.We have developed a tandem mass spectrometry method that is capable of simultaneously quantifying free, conjugated, and halogenated estrogens at picomolar levels in wastewater effluent and coastal seawater. The method was validated using treated effluent from the greater Boston metropolitan area, where we found that halogenated estrogens represented over 50 % of the total estrogen discharge flux. A kinetic model of estrogen halogenation was used to predict the distribution of free and halogenated forms in wastewater effluent and suggested that chlorinated estrogens may be formed en route to the wastewater treatment plant.In the receiving waters of Massachusetts Bay, we detected a range of conjugated, free, and halogenated forms at concentrations that were well-predicted by dilution near the sewage outfall. Farther downstream, we found significantly higher estrone concentrations which points to large inputs of estrogens from sources other than sewage. 4Finally, we have used compound-specific measurements of 13 C and 14 C in commercial and pharmaceutical estrogen preparations to evaluate the potential for using carbon isotopes to distinguish between synthetic and endogenous steroids in wastewater and other environmental matrices. Our results show that synthetic estrogens and progestogens exhibit significantly depleted δ 13 C values (~ -30 ‰) compared to endogenous steroids (-16 ‰ to -26 ‰). This isotopic difference should make it possible to apportion synthetic and endogenous hormone sources in complex environments.

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Novel Fragmentation Pathways of Anionic Adducts of Steroids Formed by Electrospray Anion Attachment Involving Regioselective Attachment, Regiospecific Decompositions, Charge-Induced Pathways, and Ion–Dipole Complex Intermediates

Cited by 39 publications

References 60 publications

Analysis of sesquiterpene pyridine alkaloids using ESI–MS/MS: The product ion at m / z 310 formed by an ion–dipole intermediate

Analysis of sesquiterpene pyridine alkaloids using ESI–MS/MS: The product ion at m / z 310 formed by an ion–dipole intermediate

Formation and Fragmentation of Unsaturated Fatty Acid [M – 2H + Na]^– Ions: Stabilized Carbanions for Charge-Directed Fragmentation

Natural and synthetic estrogens in wastewater treatment plant effluent and the coastal ocean

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Novel Fragmentation Pathways of Anionic Adducts of Steroids Formed by Electrospray Anion Attachment Involving Regioselective Attachment, Regiospecific Decompositions, Charge-Induced Pathways, and Ion–Dipole Complex Intermediates

Cited by 39 publications

References 60 publications

Analysis of sesquiterpene pyridine alkaloids using ESI–MS/MS: The product ion at m / z 310 formed by an ion–dipole intermediate

Analysis of sesquiterpene pyridine alkaloids using ESI–MS/MS: The product ion at m / z 310 formed by an ion–dipole intermediate

Formation and Fragmentation of Unsaturated Fatty Acid [M – 2H + Na]– Ions: Stabilized Carbanions for Charge-Directed Fragmentation

Natural and synthetic estrogens in wastewater treatment plant effluent and the coastal ocean

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Product

Resources

About

Formation and Fragmentation of Unsaturated Fatty Acid [M – 2H + Na]^– Ions: Stabilized Carbanions for Charge-Directed Fragmentation