Ran Zhao

Levoglucosan (LG) is highly abundant in biomass pyrolysate and is widely used as a tracer for biomass burning in environmental sciences. Current analytical standards rely on gas or liquid chromatography coupled with mass spectrometry (GC/LC-MS). Because these methods are expensive, there is a critical need for low-cost alternatives. This work explores using commercial glucometer strips to detect and quantify LG by first converting it into d-glucose with heat and acid. The hydrolysis condition was optimized to be at 150 °C, with 0.1 M H2SO4, for 60 min, while the sample was buffered at pH 7.3 for optimal detection. Following the optimization of the hydrolysis protocol, the glucometer strip signal exhibited a linear response, which was statistically indistinguishable from the response to d-glucose. However, when applied to authentic biomass burning filter samples, the glucometer method yielded concentrations approximately twice as high as GC–MS measurements. This discrepancy is likely due to interfering compounds in the sample matrix that also release d-glucose upon hydrolysis. Overall, this study establishes the proof-of-concept for using off-the-shelf glucometer testing strips for LG detection, while highlighting the distinct challenges of applying this method to complex environmental samples.

Although boreal wildfires are a major global source of trace gases, their emissions remain poorly characterized. To address this gap, controlled burns of Canadian Boreal surface and ground fuels were conducted during the Biomass Burning Canada (BBCan) Campaign. Emission factors (EF) for 46 volatile organic compounds (VOC) were determined using iodide chemical ionization mass spectrometry (I-CIMS) and Vocus proton transfer reaction mass spectrometry (Vocus PTR-MS). Total non-methane organic compound (NMOC) emissions, which were measured separately, were found to account for 1–13 % of total emitted gas-phase carbon (i.e., CO₂, CO, CH₄, NMOC), with total quantified VOCs (ΣVOCs) accounting for 13–34 % of that fraction. The dominant compounds contributing to the measured ΣVOCs include oxygenates and organic reactive nitrogen (Nr) species. Boreal peat fuels, which are prone to residual smoldering combustion, produced significantly higher total NMOC, total Nr, and individual VOC emissions than the other fuels. In contrast, boreal mulch, which burned very efficiently, produced low emissions. Combustion efficiency was observed to have a strong impact on total and individual VOC emissions, but VOC emission profiles were also dependent on fuel type and moisture content. The findings indicate that the EFs currently used to speciate NMOC emission may not adequately capture emissions from smoldering boreal peat fires. Study results provide the first comprehensive VOC EF for fresh emissions for a range of Canadian boreal surface and ground fuels, which can be used to improve emission inventories and enhance predictions of wildfire smoke impacts on air quality, climate, and health.

Although boreal wildfires are a major global source of trace gases, their emissions remain poorly characterized. To address this gap, controlled burns of Canadian Boreal surface and ground fuels were conducted during the Biomass Burning Canada (BBCan) Campaign. Emission factors (EF) for 46 volatile organic compounds (VOC) were determined using iodide chemical ionization mass spectrometry (I-CIMS) and Vocus proton transfer reaction mass spectrometry (Vocus PTR-MS). Total non-methane organic compound (NMOC) emissions, which were measured separately, were found to account for 1–13 % of total emitted gas-phase carbon (i.e., CO₂, CO, CH₄, NMOC), with total quantified VOCs (ΣVOCs) accounting for 13–34 % of that fraction. The dominant compounds contributing to the measured ΣVOCs include oxygenates and organic reactive nitrogen (Nr) species. Boreal peat fuels, which are prone to residual smoldering combustion, produced significantly higher total NMOC, total Nr, and individual VOC emissions than the other fuels. In contrast, boreal mulch, which burned very efficiently, produced low emissions. Combustion efficiency was observed to have a strong impact on total and individual VOC emissions, but VOC emission profiles were also dependent on fuel type and moisture content. The findings indicate that the EFs currently used to speciate NMOC emission may not adequately capture emissions from smoldering boreal peat fires. Study results provide the first comprehensive VOC EF for fresh emissions for a range of Canadian boreal surface and ground fuels, which can be used to improve emission inventories and enhance predictions of wildfire smoke impacts on air quality, climate, and health.

Although boreal wildfires are a major global source of trace gases, their emissions remain poorly characterized. To address this gap, controlled burns of Canadian Boreal surface and ground fuels were conducted during the Biomass Burning Canada (BBCan) Campaign. Emission factors (EF) for 46 volatile organic compounds (VOC) were determined using iodide chemical ionization mass spectrometry (I-CIMS) and Vocus proton transfer reaction mass spectrometry (Vocus PTR-MS). Total non-methane organic compound (NMOC) emissions, which were measured separately, were found to account for 1–13 % of total emitted gas-phase carbon (i.e., CO₂, CO, CH₄, NMOC), with total quantified VOCs (ΣVOCs) accounting for 13–34 % of that fraction. The dominant compounds contributing to the measured ΣVOCs include oxygenates and organic reactive nitrogen (Nr) species. Boreal peat fuels, which are prone to residual smoldering combustion, produced significantly higher total NMOC, total Nr, and individual VOC emissions than the other fuels. In contrast, boreal mulch, which burned very efficiently, produced low emissions. Combustion efficiency was observed to have a strong impact on total and individual VOC emissions, but VOC emission profiles were also dependent on fuel type and moisture content. The findings indicate that the EFs currently used to speciate NMOC emission may not adequately capture emissions from smoldering boreal peat fires. Study results provide the first comprehensive VOC EF for fresh emissions for a range of Canadian boreal surface and ground fuels, which can be used to improve emission inventories and enhance predictions of wildfire smoke impacts on air quality, climate, and health.

Although boreal wildfires are a major global source of trace gases, their emissions remain poorly characterized. To address this gap, controlled burns of Canadian Boreal surface and ground fuels were conducted during the Biomass Burning Canada (BBCan) Campaign. Emission factors (EF) for 46 volatile organic compounds (VOC) were determined using iodide chemical ionization mass spectrometry (I-CIMS) and Vocus proton transfer reaction mass spectrometry (Vocus PTR-MS). Total non-methane organic compound (NMOC) emissions, which were measured separately, were found to account for 1–13 % of total emitted gas-phase carbon (i.e., CO₂, CO, CH₄, NMOC), with total quantified VOCs (ΣVOCs) accounting for 13–34 % of that fraction. The dominant compounds contributing to the measured ΣVOCs include oxygenates and organic reactive nitrogen (Nr) species. Boreal peat fuels, which are prone to residual smoldering combustion, produced significantly higher total NMOC, total Nr, and individual VOC emissions than the other fuels. In contrast, boreal mulch, which burned very efficiently, produced low emissions. Combustion efficiency was observed to have a strong impact on total and individual VOC emissions, but VOC emission profiles were also dependent on fuel type and moisture content. The findings indicate that the EFs currently used to speciate NMOC emission may not adequately capture emissions from smoldering boreal peat fires. Study results provide the first comprehensive VOC EF for fresh emissions for a range of Canadian boreal surface and ground fuels, which can be used to improve emission inventories and enhance predictions of wildfire smoke impacts on air quality, climate, and health.

Although boreal wildfires are a major global source of trace gases, their emissions remain poorly characterized. To address this gap, controlled burns of Canadian Boreal surface and ground fuels were conducted during the Biomass Burning Canada (BBCan) Campaign. Emission factors (EF) for 46 volatile organic compounds (VOC) were determined using iodide chemical ionization mass spectrometry (I-CIMS) and Vocus proton transfer reaction mass spectrometry (Vocus PTR-MS). Total non-methane organic compound (NMOC) emissions, which were measured separately, were found to account for 1–13 % of total emitted gas-phase carbon (i.e., CO2, CO, CH4, NMOC), with total quantified VOCs (ΣVOCs) accounting for 13–34 % of that fraction. The dominant compounds contributing to the measured ΣVOCs include oxygenates and organic reactive nitrogen (Nr) species. Boreal peat fuels, which are prone to residual smoldering combustion, produced significantly higher total NMOC, total Nr, and individual VOC emissions than the other fuels. In contrast, boreal mulch, which burned very efficiently, produced low emissions. Combustion efficiency was observed to have a strong impact on total and individual VOC emissions, but VOC emission profiles were also dependent on fuel type and moisture content. The findings indicate that the EFs currently used to speciate NMOC emission may not adequately capture emissions from smoldering boreal peat fires. Study results provide the first comprehensive VOC EF for fresh emissions for a range of Canadian boreal surface and ground fuels, which can be used to improve emission inventories and enhance predictions of wildfire smoke impacts on air quality, climate, and health.

Vaping e-cigarette juice (e-juice) is popular among young consumers. Although e-juice compositions are well characterized, chemical transformations during indoor storage are often overlooked. Particularly, the fundamentals of nicotine oxidation in aged e-juices remain poorly understood, despite rising consumer concerns. This work utilizes p-toluenesulfonyl chloride (TsCl) derivatization, coupled with analysis by liquid chromatography-mass spectrometry (LC-MS) and electron paramagnetic resonance (EPR) spectroscopy, to study nicotine oxidation under a realistic storage environment. We report that tobacco-specific alkaloids (TSAs), including nornicotine (NN) and anabasine (ANA), can accumulate in aged e-juice. These compounds are immediate precursors of carcinogens. Within nine days of storage, NN concentration can reach up to 250 μmol/L and can remain elevated during prolonged storage. This concentration is 6 times higher than that of fresh e-juices and more than 270 times higher than that of typical human saliva. A hydroxyl radical oxidation (OH-oxidation) experiment indicated that the indoor OH-oxidation of nicotine yields TSAs. Lastly, we propose a radical-driven mechanism supported by the detection of nitroxide radicals in the EPR spectra. These radicals demonstrated strong correlations with nicotine (R² = 0.94-0.98). This work reveals the transformation of nicotine in popular consumable products and highlights the importance of encouraging proper e-juice storage practices.