RESUMO
Cold-chain environment could extend the survival duration of SARS-CoV-2 and increases the risk of transmission. However, the effect of clod-chain environmental factors and packaging materials on SARS-CoV-2 stability and the efficacy of intervention measures to inactivate SARS-CoV-2 under cold-chain environment remains uncertain. This study aimed to unravel cold-chain environmental factors that preserved the stability of SARS-CoV-2 and disinfection measures against SARS-CoV-2 under the cold-chain environment. The spike gene of SARS-CoV-2 isolated from Wuhan hu-1 was used to construct the SARS-CoV-2 pseudovirus and used as model of the SARS-CoV-2 virus. The decay rate of SARS-CoV-2 pseudovirus in the cold-chain environment, various types of packaging material surfaces i.e., PE plastic, stainless steel, Teflon and cardboard, and in frozen seawater was investigated. The influence of LED visible light(wavelength 450 nm-780 nm) and airflow movement on the stability of SARS-CoV-2 pseudovirus at -18{degrees} C were subsequently assessed. The results show that SARS-CoV-2 pseudovirus decayed more rapidly on porous cardboard surface compared with the non-porous surfaces including PE plastic, stainless steel and Teflon. Compared with 25{degrees} C, the decay rate of SARS-CoV-2 pseudovirus was significantly lower at low temperature. Seawater preserved viral stability both at -18{degrees} C and repeated freeze-thawing cycles compared with deionized water. LED visible light illumination and airflow movement environment at -18{degrees} C reduced the SARS-CoV-2 pseudovirus stability. In conclusion, our results indicate cold-chain temperature and seawater as risk factors for SARS-CoV-2 transmission and LED visible light illumination and airflow movement as possible disinfection measures of SARS-CoV-2 under the cold-chain environment. ImportanceIt is widely recognized that low temperature is a condition for maintaining virus vitality, and cold-chain transportation spreads the events of the SARS-CoV-2 were reported. This study provides that the decay rate of the SARS-CoV-2 pseudovirus at low temperatures varies on different packaging materials, and salt ions present in frozen foods such as seafood may protect virus survival. These results provide evidence for the possibility of SARS-CoV-2 transmission through cold-chain transport and also suggest the importance for disinfection of items. However, the commonly used disinfection methods of ultraviolet radiation and chemical reagents are generally not suitable for the disinfection of frozen food. Our study shows LED visible light illumination and airflow movement as possible disinfection measures of SARS-CoV-2 under the cold-chain environment. This has implications for reducing the long-distance transmission of the virus through cold-chain transportation.
RESUMO
A method was developed for determination of thirteen amines including seven aliphatic amines, two heterocyclic amines and four aromatic amines in atmospheric particulate matter (PM) by gas chromatography-mass spectrometry (GC-MS). Samples were ultrasonically extracted with ultra-pure water and derivatized with benzenesulfonyl chloride (BSC) under alkaline conditions. The derivatives were extracted with dichloromethane and then detected by GC-MS using DB-5MS chromatographic column. The method detection limit (S/N=3) and quantitation limit (S/N=10) were 0.00008-0.017 μg/mL and 0.00026-0.0565 μg/mL respectively, and the correlation coefficients were 0.9903-0.9996, which indicated that the standard curve had good linear correlation. In addition, the relative standard deviation was less than 30％ and the average recovery was 54.4％-159.7％ except for methylamine and benzylamine at spiked level of 1.0 μg/mL, showing high precision and accuracy. 9 kinds of amines were detected in the PM2.5 samples collected in Guangzhou city by this method, among which dimethylamine and butylamine accounted for 90％ of the total nine amines, which indicated that they were primary amines in PM2.5; while propylamine exhibited the lowest level in PM2.5 with the concentration less than 1.0 ng/m3.
RESUMO
Volatility can influence the lifetime of particles in the atmosphere, and provide useful information on the formation of secondary aerosol. The previous studies generally utilized thermodenuder ( TD ) to investigate the volatility behavior of particles. Using TD, semivolatile species are vaporized at different temperature, and the vaporized gas is adsorpted by activated charcoal. However, carbon might be emitted from activated charcoal under high temperature or activated charcoal ageing. In this study, a new method was developed for the measurement of particle volatility by coupling a thermodiluter system to an online single particle aerosol mass spectrometer ( SPAMS) . Aerosol particles were passed into two different channels, and then analyzed by SPAMS. Through Channel 1, aerosol particles were heated to different temperature by heating tube, then non-volatile particles and volatile gas entered into the diluter. After diluting and cooling by diluent air, the non-volatile particles were analyzed by SPAMS. Through Channel 2, aerosol particles were analyzed directly by SPAMS without the heating process. Particle volatility was obtained by comparing the information ( particle size, particle number and mass spectrum ) of particles through Channels 1 and 2. Laboratory tests showed that the diluter could avoid the re-condensation of volatiles to the particles. This developed method was applied in the real time measurement of individual particle volatility in the spring of Guangzhou. The results showed that these particles were primarily comprised of highly volatile and moderate volatile species.
