Ion trap mass spectrometry affords advances in the analytical and atmospheric chemistry of 2-hydroxy-2-methylpropanal, a proposed photooxidation product of 2-methyl-3-buten-2-ol

Abstract

In the western United States, in areas where emissions of the biogenic hydrocarbon, 2-methyl-3-buten-2-ol (MBO) are high, MBO contributes significantly to the oxidative capacity of the atmosphere. Hydroxyl radical oxidation of MBO can play an important role in forming tropospheric ozone, and MBO reaction products may contribute to the formation of secondary organic aerosols [1][2][3]. Although 2-hdyroxy-2-methylpropanal was tentatively identified as a product from the reaction of MBO with ⅐OH in indoor chamber studies, the identity of the compound was not confirmed due to the lack of an authentic standard. Further, no data exists on the atmospheric generation and fate of 2-hydroxy-2-methylpropanal in the ambient environment. Herein, we provide further evidence that 2-hydroxy-2-methylpropanal is generated by ⅐OH reaction with MBO by identifying 2-hydroxy-2-methylpropanal in an indoor chamber experiment and in ambient air sampled in the Blodgett Forest, where MBO emissions are high. We analyzed 2-hydroxy-2-methylpropanal by using a method that relies on O- (2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) and bis-(trimethylsilyl) trifluoroacetamide (BSTFA) derivatization along with ion-trap mass spectrometry. Tentative identification of 2-hydroxy-2-methylpropanal was possible by using knowledge gained in this study regarding the mass spectrometry of PFBHA-BSTFA derivatives of carbonyls with primary, secondary, and tertiary ϪOH groups, and ado-and keto-acids. The identification was confirmed by comparing the methane CI mass spectra and relative gas chromatographic retention time obtained by analyzing 2-hydroxy-2-methylpropanal in a sample extract and a synthesized authentic standard. Since the standard became available at the end of this study (after all samples were analyzed), we also developed a method for semi-quantification of 2-hydroxy-2-methylpropanal, with a detection limit of 27 pptv in air. We used the method to provide the first ambient air measurements of 2-hydroxy-2-methylpropanal. The analyte is not commercially available, and hence other researchers who have not synthesized an authentic standard can employ the method. (J Am Soc Mass Spectrom 2002, 13, 530 -542)

A General and Efficient Heterogeneous Gold‐Catalyzed Hydration of Nitriles in Neat Water under Mild Atmospheric Conditions

“…All the tested compounds presented a neutral loss of 181 amu (C 6 F 5 N) among other ions. This type of fragmentation was previously observed in other studies when analyzing pentafluorobenzylhydroxylamine PFBHA38, 39 and PFPH derivatives of carbonyl compounds 32, 33. Neutral loss scans were performed in order to confirm the previous results and 19 of the 24 compounds under study were detected under neutral loss scanning of 181 amu.…”

“…Moreover, the results obtained with oxoacids suggested that the signal intensity was enhanced when the distance between the ketone and the carboxyl group increased. Nevertheless, additional experiments involving a higher number of oxoacids would be required to confirm this observation, and the α‐oxoacids were rarely reported in the literature contrarily to ω‐oxoacids that have been often identified in atmospheric POM samples 38–43…”

Characterization of secondary atmospheric photooxidation products: Evidence for biogenic and anthropogenic sources

“…Therefore, the PFBHA and PFBHA‐BSTFA derivatives of 2‐HMPR were identified by interpreting the EI, methane CI, and PFBOH CI ion trap mass spectra, and by matching the relative retention times and mass spectra to those of a peak obtained from the reaction of MBO with hydroxyl radical in an atmospheric chamber experiment. Identification was later confirmed by matching the relative retention time and mass spectra to that from a derivative of a synthesized authentic standard [ Spaulding et al , 2002b].…”

“…However, in previous work we compared this method to FT‐IR measurements in which 2‐HMPR mixing ratios were estimated by assuming a yield 29% (equal to the yield of formaldehyde) from the reaction of MBO with OH radicals. According to this comparison, the error of the method ranges from 6 to 41%, depending on the assumed yield of 2‐hydroxy‐2‐methylpropanal [ Spaulding et al , 2002b].…”

Supplementary material to "Evaluated kinetic and photochemical data for atmospheric chemistry: Volume VIII – gas phase reactions of organic species with four, or more, carbon atoms (≥ C<sub>4</sub>)"

“…The reaction proceeds almost totally by initial addition of HO to the C=C bond (Fantechi et al, 1998b;Ferronato et al, 1998;Alvarado et al, 1999;Spaulding et al, 2002;Reisen et al, 2003;Carrasco et al, 2007). In the presence of NO at atmospheric pressure of air the observed products are formaldehyde, acetone, glycolaldehyde, 2-hydroxy-2-methylpropanal [(CH3)2C(OH)CHO], and dihydroxynitrates [presumed to be (CH3)2C(OH)CH(OH)CH2ONO2 and (CH3)2C(OH)CH(ONO2)CH2OH] (Fantechi et al, 1998b;Ferronato et al, 1998;Alvarado et al, 1999;Spaulding et al, 2002;Reisen et al, 2003;Carraso et al, 2007).…”