Simultaneous Quantification of H2O2 and Organic Hydroperoxides by 1H NMR Spectroscopy.
Anal Chem
; 94(15): 5729-5733, 2022 04 19.
Article
em En
| MEDLINE
| ID: mdl-35394743
ABSTRACT
Due to similar reactivity of organic hydroperoxides (OHPs), an HPLC separation step is typically required for their indirect (chemical) quantification in mixtures. The high sensitivity of chemical shifts to chemical structure makes NMR an ideal tool for the simultaneous quantification of OHPs in mixtures, but the concentration of these analytes in the samples of interest is usually well below the sensitivity of standard NMR experiments. This sensitivity problem can be mitigated by taking advantage of the fact that the z magnetization of the H2O2 resonance recovers at the rate of hydrogen exchange with water, which is significantly faster than longitudinal relaxation, thus enabling very fast scanning for signal-to-noise enhancement. An adaptation of the E-BURP2 pulse is described that suppresses the water signal by more than 4 orders of magnitude, yielding uniform excitation of peroxide signals without interference of the ca. 108-fold stronger H2O resonance. We demonstrate the method for a mixture of OHPs and report the chemical shifts for multiple OHPs that are of interest in atmospheric chemistry. As shown for hydroxymethyl hydroperoxide, the chemical decay of OHPs can be tracked directly by NMR spectroscopy.
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MEDLINE
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Imageamento por Ressonância Magnética
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Peróxido de Hidrogênio
Idioma:
En
Ano de publicação:
2022
Tipo de documento:
Article