| The off-line detection methods of environmental samples often require pre-concentration,derivatization and other pre-treatment processes,and the multi-step analysis process is timeconsuming and labor-intensive,which may be prone to human errors.Measurements with higher temporal resolution enable high-throughput detection of samples and more accurately determine real-time concentrations of contaminants.Organic amines are an important group of nitrogen-containing pollutants,which not only pollute the environment,but also cause adverse health effects on the human body through inhalation,ingestion,and skin contact.The detection of organic amines in environmental samples is a challenging problem,and it is difficult to determine directly in complex matrices due to its high volatility,high polarity,poor stability,high solubility,and low concentration.N-nitrosamines are a group of derivatized amines that are mutagenic,teratogenic and hepatotoxic.The U.S.Environmental Protection Agency(U.S.EPA)has classified NDMA,NMEA,NDEA,NDPA,NDBA,NDPhA and NPYR as a Group B2 human carcinogen.Based on dopant-assisted atmospheric pressure photoionization time-of-flight mass spectrometry(DA-APPI-TOFMS)and on-line purge-release device,an on-line rapid detection method for Nnitrosamines in beer was developed.N-nitrosamines are extracted from the solution to the gas phase by using the microbubbles generated by N2 purge,online analysis of N-nitrosamines in beer was realized without sample pretreatment.In order to improve the ionization efficiency of N-nitrosamines,the DA-APPI ionization source was improved by using a high-power deuterium lamp as the photoionization source,and the detection method of ethanol indirectly assisted chemical ionization was developed using ethanol as dopant,which increased the sensitivity by 4 times.Through the three-zone structure ionization source and humidity dilution design,the influence of humidity on the DA-APPI ionization source was solved.Subsequently,through the optimization of solution salinity,water bath temperature,flow rate and other instrument conditions,the detection sensitivity of seven N-nitrosamines reached ng/L level.Only 1.5 mL sample was consumed during the entire analysis,and the detection time of a single sample was only 5 min.The on-line detection method was successfully used for the detection of N-nitrosamines in beer samples.Formamide has been classified as a Class 1B reproductive toxicant to children by the European Union(EU)Chemicals Agency.Children’s foam mats are a potential source of formamide and ammonia,and in this paper,an on-line DA-APPI-TOFMS coupled with a Teflon environmental chamber was developed to assess the exposure risk of formamide and ammonia from foam mats to children,with a measurement time of 20 s for a single sample.The emissions of formamide and ammonia were measured from 21 foam mats with three different raw material types:with ethylene-vinyl acetate(EVA:n=7),polyethylene(PE:n=7)and cross-linked polyethylene(XPE:n=7).High levels of formamide(average 3363.72 mg/m3)and ammonia(average 1586.78 mg/m3)emissions were detected in 21 foam mats of 3 different materials,and emissions with EVA and PE mats were about two orders of magnitude higher than XPE mats.The results of the factors affecting the emissions showed that it was positively correlated with temperature and negatively correlated with air exchange rate,while the specific emission rate(SER)was positively correlated with air exchange rate.The 28-day emission testing for the selected PE mat showed that the emissions of formamide were two orders of magnitude higher than the EU emission limit of 20 μg/m3,and formamide may be a permanent indoor contaminant for foam mat products during their lifecycle.The exposure assessment of children aged 0.5-6 years showed that age group 0.5-2 years were subject to higher exposures than others.Thus,this study provided key relevant information for further studies on assessing children exposure to indoor air pollution from foam mats. |
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