Advanced Oxidation of Caffeine in Water:  On-Line and Real-Time Monitoring by Electrospray Ionization Mass Spectrometry

Dalmázio, Ilza; Santos, Leonardo S.; Lopes, Renata Pereira; Eberlin, Marcos N.; Augusti, Rodinei

doi:10.1021/es047985v

Cited by 131 publications

(91 citation statements)

References 60 publications

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“…17,18 ESI-MS(/MS) with its unique characteristics has become a major technique to elucidate reaction mechanism especially in aqueous solutions via the detection and identification of reactants, products, and intermediates, 19,20 even the shortlived ones that occur at very low concentrations. 21,22 Gas chromatography-mass spectrometry (GC-MS) has often been the technique of choice for reaction screening and product elucidation.…”

Section: Introductionmentioning

confidence: 99%

Monitoring of β-blockers ozone degradation via electrospray ionization mass spectrometry

Quispe¹,

Nachtigall²,

Fonseca³

et al. 2011

J. Braz. Chem. Soc.

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As estruturas dos produtos de degradação mediada por ozônio de diferentes compostos farmacêuticos foram estudadas. Uma completa degradação do nadolol foi observada nas condições empregadas após 100 min. Os produtos de degradação obtidos nas soluções aquosas foram caracterizados por espectrometria de massas com ionização por electrospray (ESI-MS e ESI-MS/MS). O mecanismo proposto para a degradação consiste inicialmente do ataque de ozônio ao grupo amino da anilina formando nitro compostos, seguida de uma série de processos oxidativos. Monitoramento por ESI-MS(/MS) mostrou que a degradação de atenolol (ATE) e acebutolol (ACE) por ozônio ocorrem via um mecanismo similar ao do nadolol.The structures of intermediate products of ozone degradation of different pharmaceutical compounds have been studied. Under the conditions employed, complete ozone degradation of nadolol was achieved after 100 min. The degradation products obtained in aqueous solution were characterized by electrospray ionization mass (and tandem mass) spectrometry (ESI-MS and ESI-MS/MS). The proposed mechanism for degradation, ozone attacks at the aniline amino group giving rise to nitro compounds and further degradation occurs via a series of oxidative processes. Continuous online monitoring by ESI-MS(/MS) with high accuracy mass measurements showed that ozone degradation of atenolol (ATE) and acebutolol (ACE) occurs via mechanisms similar to that of nadolol.

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Section: Introductionmentioning

confidence: 99%

Monitoring of β-blockers ozone degradation via electrospray ionization mass spectrometry

Quispe¹,

Nachtigall²,

Fonseca³

et al. 2011

J. Braz. Chem. Soc.

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“…[27][28][29] Electrospray ionization mass spectrometry (ESI-MS), because of its appealing and unique attributes, has rapidly becoming an alternative approach suitably employed to a direct monitoring of a increasing number of relevant environmental processes. [30][31][32][33][34][35][36][37][38][39][40] In these inquiries, the information provided by the MS (the m/z values of the ionic species) and MS/MS data (the fragmentation profiles of a given mass-selected ion) are meticulously evaluated aiming to propose chemical structures of products (and in some cases transient intermediates) likely formed in the condensed phase. 41 The identification of by-products arising from oxidative treatments, which can be more risky than the own precursors indeed, 42 is an important point that must be taken into consideration for the evaluation of the overall performance of a given process.…”

Section: Introductionmentioning

confidence: 99%

Ozonation of ethinylestradiol in aqueous-methanolic solution: direct monitoring by electrospray ionization mass spectrometry

Vieira¹,

Nascentes²,

Augusti³

2010

J. Braz. Chem. Soc.

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A ozonólise do etinilestradiol (1), um hormônio sintético esteroidal, numa solução de água/metanol foi investigada. Análises por HPLC-UV revelaram que o hormônio foi completamente consumido, tanto em pH 5 quanto 8, após um tempo reacional de 20 min. O monitoramento por espectrometria de massas com ionização electrospray no modo negativo (ESI(-)-MS) revelou o contínuo consumo de 1 (detectado em sua forma desprotonada, [1 -H] -, de m/z 295), concomitantemente com o aparecimento de produtos de oxidação. Estruturas químicas foram propostas para tais produtos com base nos dados de MS (valores de m/z) e MS/MS (padrões de fragmentação dos ânions). Estes dados, em associação com conhecimento sobre a reatividade de moléculas orgânicas frente ao ozônio em solução aquosa, foram avaliados e uma rota reacional inédita para a ozonização do etinilestradiol foi sugerida. Assim, como primeira etapa nesta sequência reacional propôs-se uma adição 1,3-dipolar do ozônio sobre o anel fenólico de 1 para gerar o produto di-hidroxilado 2 (detectado como [2 -H] -de m/z 311). A perda de acetileno como o único canal de dissociação de [2 -H] -confirmou que a hidroxilação ocorreu no anel fenólico e não na porção acetilênica de 1. Oxidações subsequentes foram propostas para explicar a formação de outros produtos, todos eles contendo o grupo funcional COOH (como verificado pela dissociação das respectivas moléculas desprotonadas através da perda característica de CO 2 ). Os dados de ESI(-)-MS também revelaram diferenças notáveis entre as reações conduzidas em pH 5 e 8, i.e., em meios levemente ácido e básico, respectivamente.The ozonolysis of ethinylestradiol (1), a synthetic steroidal estrogen, in an aqueous-methanolic solution was investigated. HPLC-UV analyses revealed that 1 was completely consumed after a 20 min reaction time either at pH 5 or 8. ESI(-)-MS (electrospray ionization mass spectrometry in the negative ion mode) monitoring also revealed the continuous consumption of 1 (detected as [1 -H] -of m/z 295) concomitantly with the emergence of oxidation products. Chemical structures were proposed for these products based on the data of MS and MS/MS (the m/z values and fragmentation profiles of the anionic specie, respectively). These data, in conjunction with the well-established knowledge about the reactivity of organic molecules toward ozone in aqueous solution, were evaluated and an unprecedented reaction route for the ozonation of 1 could thus be suggested. Hence, the first step in this reaction sequence was ascribed to involve a 1,3-dipolar cycloaddition of ozone at the phenolic ring of 1 yielding the di-hydroxylated product 2 (detected as [2 -H] -of m/z 311). The loss of acetylene as the unique dissociation channel for [2 -H] -thus confirmed that such hydroxylation occurred at the phenolic ring rather than the acetylenic moiety of 1. Subsequent oxidations were proposed to be the origin of a number of other products, all of them bearing the COOH functionally (this was verified by the characteristic loss of CO 2 during the...

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“…These convenient features make these methods ideal to analyze compounds with a broad range of polarities and stabilities. Because of that, ESI-MS and APCI-MS have been extensively used to acquire relevant and unprecedented information about transient and unstable species formed during the course of a number of chemical reactions in aqueous solutions [20 -22], including oxidation processes [23][24][25][26][27].…”

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confidence: 99%

Monitoring the degradation of tetracycline by ozone in aqueous medium via atmospheric pressure ionization mass spectrometry

Dalmázio

Almeida

Augusti

et al. 2007

J. Am. Soc. Mass Spectrom.

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171

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The degradation of tetracycline (1) by ozone in aqueous solution was investigated. High performance liquid chromatography (HPLC), UV-visible spectroscopy (UV-Vis), and total organic carbon (TOC) analyses revealed that although tetracycline was quickly consumed under this oxidative condition, it did not mineralize at all. Continuous monitoring by electrospray ionization mass spectrometry in the positive ion mode, ESI(ϩ)-MS, revealed that tetracycline (1), detected in its protonated form ([1 ϩ H] ϩ ) of m/z 445, reacted to yield almost exclusively two unprecedented oxidation products (2 and 3) via a net insertion of one and two oxygen atoms, respectively. Compound 2, suggested to be formed via an initial 1,3-dipolar cycloaddition of ozone at the C11a-C12 double-bond of 1, and Compound 3, proposed to be produced via a subsequent ozone attack at the C2-C3 double-bond of 2, were detected in their protonated forms in the ESI(ϩ)-MS, i.e.,

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Advanced Oxidation of Caffeine in Water: On-Line and Real-Time Monitoring by Electrospray Ionization Mass Spectrometry

Cited by 131 publications

References 60 publications

Monitoring of β-blockers ozone degradation via electrospray ionization mass spectrometry

Monitoring of β-blockers ozone degradation via electrospray ionization mass spectrometry

Ozonation of ethinylestradiol in aqueous-methanolic solution: direct monitoring by electrospray ionization mass spectrometry

Monitoring the degradation of tetracycline by ozone in aqueous medium via atmospheric pressure ionization mass spectrometry

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