Fuente: PubMed "industrial biotechnology" Anal Chem. 2026 Jun 2. doi: 10.1021/acs.analchem.5c07134. Online ahead of print.ABSTRACTOxygenated volatile organic compounds (OVOCs) play an essential role in atmospheric oxidation reactions and serve as precursors for ROX radicals, O3, and secondary organic aerosol (SOA). Nevertheless, there are still relatively limited studies on OVOCs with high molecular weight, which are largely disregarded in methods for detection. In light of these challenges, we designed an NH4+-based ion source with a time-of-flight mass spectrometer and systematically optimized the operating pressure. Over a broad pressure range of 74-1000 mbar, the ion source maintained stable performance, with the highest sensitivity and humidity tolerance observed at 96 mbar. The instrument showed high sensitivities to OVOCs, especially to aldehydes and ketones, yet low to alkanes and alkenes. Moreover, α-pinene ozonolysis reactions showed that it was feasible to detect OVOCs with varying oxidation states from O1 to O10 with high sensitivities by NH4+-CIMS. The results verified the ability to detect early generation oxidation products, such as the rarely reported C10H14O and C10H16O compounds, which were likely formed through the terminal reactions of C10H15O2 radicals. In addition, during a one-week field campaign in Beijing, NH4+-CIMS and the offline method yielded comparable concentration levels, with average concentrations of ∼100 ppt. These results indicated that the NH4+-CIMS can serve as an appropriate tool for the detection of early generation oxidation products and high-molecular-weight OVOCs under both laboratory and ambient conditions.PMID:42228863 | DOI:10.1021/acs.analchem.5c07134