Abstract:

Statistical evidence indicates that individuals spend approximately 90% of their time indoors on a daily basis. A multitude of human activities， including incense burning， cooking， smoking， and the use of electrical appliances， can contribute to indoor air pollution. This phenomenon poses a significant risk of indoor exposure to human health risks. Incense burning， as one of the major indoor pollution sources， has been increasing in use in recent years due to its special effects in religious practices and regional lifestyles. Incense usually consists of herbs， wood powder， bamboo sticks， scented materials， and binder powders， and the specific chemical composition of each type of material is complex due to different uses and manufacturing processes； and the degree of complete combustion， thermal degradation and volatilization processes of different types of incense vary greatly， resulting in the release of gaseous and particulate organic compounds whose compositions are not yet clear. Studies have shown that the emission factors of particulate matter released from incense burning may be much higher than those produced during the combustion of charcoal， wood and cigarettes. The levels of organic pollutants emitted by incense burning， such as aromatic hydrocarbons， esters， ketones， benzenes， and phenols， are much higher than outdoor levels. Prolonged exposure to incense smoke has been shown to cause respiratory damage and potential genotoxicity. Therefore， accurate identification and measurement of the organic pollutants emitted from incense burning is particularly important to accurately assess their environmental and population health risks. Herein， this study established an analytical method based on ultrasonic extraction-gas chromatography-mass spectrometry （GC-MS） for the simultaneous determination of 67 organic compounds in gaseous and particulate emissions from incense burning. These compounds include 29 esters， seven benzene series， 14 phenols， and 17 polycyclic aromatic hydrocarbons （PAHs）. Particulate and gaseous components released during indoor incense burning were collected using quartz filter membrane and self-made XAD-2 resin sampling tubes， respectively. Non-targeted analysis of incense components was performed using a GC-quadrupole-Orbitrap high-resolution mass spectrometry （GC-Q-Orbitrap-HRMS） to achieve preliminary identification of trace organic compounds in the incense-burning samples. Subsequently， targeted analysis was conducted using GC-MS in selected ion monitoring （SIM） mode， with quantification performed using the external standard method. Method validation results demonstrated good linearity for all 67 organic compounds within the range of 10 to 500 μg/L， with correlation coefficients （r）≥0.999 0. The limits of detection （LODs） and quantification （LOQs） were ranged from 0.02 to 0.33 µg/m³ and 0.03 to 0.67 µg/m³， respectively. At low， medium， and high spiked levels， the recoveries for the 67 organic compounds in the gaseous phase ranged from 72.7% to 119.0%， with relative standard deviations （RSDs） of 0.9% to 4.1%； for the particulate phase， the recoveries for the 67 organic compounds ranged from 71.5% to 118.9%， with RSDs of 0.7% to 9.5%. The established method was applied to the determination of indoor incense-burning samples （incense sticks and electrically heated incense powder）， and the influence of different incineration methods on the types and contents of products was analyzed. The results indicated that during the same burning duration （30 min）， the total content of gaseous and particulate organic compounds released from ignited incense sticks was higher than that from electrically heated powdered incense. The particulate organic compounds produced by the ignited incense sticks are mainly phenolics and PAHs， followed by esters， and benzene series. The composition of particulate organic compounds from electrically heated powdered incense was similar to that of incense sticks. A large amount of benzene series were detected in the gaseous organic compounds released by burning incense sticks， and the content was much higher than that of the other three types of organic compounds. The gaseous organic compounds released by electrically heated incense powder are mainly benzene series and phenols， followed by PAHs and esters. Compared with the previously reported related monitoring methods， this method is simpler and more efficient， providing a more convenient technical means for the sensitive screening of gaseous and particulate organic compounds released by incense burning.

Key words: gas chromatography-mass spectrometry （GC-MS）, incense products identification, organic compounds, indoor air