Identification of Organic Hydroperoxides and Peroxy Acids Using Atmospheric Pressure Chemical Ionization – Tandem Mass Spectrometry (APCI-MS/MS): Application to Secondary Organic Aerosol

Abstract

Abstract.Molecules with hydroperoxide functional groups are of extreme importance to both the atmospheric and biological 10 chemistry fields. In this work, an analytical method is presented for the identification of organic hydroperoxides and peroxy and peracetic acid), as well as the ROOH formed from the reactions of H 2 O 2 with aldehydes (i.e. acetaldehyde, hexanal, glyoxal and methylglyoxal). This new ROOH detection method was applied to methanol extracts of secondary organic aerosol (SOA) material generated from ozonolysis of α-pinene, indicating a number of ROOH molecules in the SOA material. While the full scan mass spectrum of SOA demonstrates the presence of monomers (m/z=80-250), dimers (m/z=250-450) and trimers (m/z=450-600), the neutral loss scan shows that the ROOH products all have masses less than 20 300 Da, indicating that ROOH molecules may not contribute significantly to the SOA oligomeric content. We anticipate this method could also be applied to biological systems with considerable value.

Toxicological Responses of α-Pinene-Derived Secondary Organic Aerosol and Its Molecular Tracers in Human Lung Cell Lines

“…By analyzing this model hydroperoxide standard with RPLC/ESI-HR-QTOFMS, we were able to determine how the hydroperoxides ionize and their typical neutral losses produced during MS/MS experiments. As shown in Figure S8 , we found that 1,2-ISOPOOH was not only retained and detected as the [M + NH 4 + ] + ion at mass-to-charge ratio ( m / z ) 136 by the RPLC/ESI-HR-QTOFMS positive ion mode method, but it also produced neutral losses of 35 (i.e., loss of H 2 O + NH 3 ) and 51 (i.e., loss of H 2 O 2 + NH 3 ) during MS/MS experiments, which are consistent with the neutral losses we observed for the proposed structures shown in Table 1 and with a prior study by Zhou et al 62 that used atmospheric pressure chemical ionization-tandem mass spectrometry (APCI-MS/MS) operated in the positive mode.…”

“…Taken together, these observations suggest that compounds other than pinonic acid, pinic acid, and MBTCA that are present in α-pinene ozonolysis SOA induce cellular toxicity. On the basis of previous studies, including work from our group on complementary systems, 54 , 59 the most likely candidate compounds are multifunctional organic peroxides that are generated from α-pinene ozonolysis. Many prior studies have measured a significant organic peroxide contribution to SOA generated from α-pinene ozonolysis, 31 , 57 including multifunctional organic peroxides.…”

Eudesmane and Eremophilane Sesquiterpenes from the Fruits of Alpinia oxyphylla with Protective Effects against Oxidative Stress in Adipose-Derived Mesenchymal Stem Cells

“…Its molecular formula, C 15 H 22 O 3 , with five degrees of unsaturation, was determined based on the high-resolution electrospray ionization mass spectrometry (HRESIMS) ion peak at m / z 251.1643 [M + H] + (calculated for C 15 H 23 O 3 + , 251.1642). The ion peak at m / z 217.1598 [M + H − H 2 O 2 ] + [ 22 , 23 ] and neutral loss of 51 Da (H 2 O 2 + NH 3 ) from the ammonium adduct, m / z 268.1872 [M + NH 4 ] + [ 24 ] are characteristic evidence for the presence of the hydroperoxy group. The 1 H-NMR spectrum of 1 showed three olefinic protons ( δ H 5.90 (dt, J = 2.9, 1.3 Hz, 1H), 5.37 (t, J = 1.3 Hz, 1H), 5.21 (brs, 1H)), one methine ( δ H 2.37 (m, 1H)), four methylenes ( δ H 2.41 (m, 1H)/1.54 (m, 1H), 2.30 (dd, J = 16.2, 1.3 Hz, 1H)/ 2.14 (dd, J = 16.2, 1.3 Hz, 1H), 2.19 (m, 1H)/1.78 (td, J = 14.1, 4.1 Hz, 1H), 1.53 (m, 1H)/1.42 (td, J = 13.9, 4.1 Hz, 1H), and three methyls ( δ H 0.96 (brs, 3H), 1.93 (t, J = 1.3 Hz, 3H), 1.84 (brs, 3H)).…”