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随着空气质量逐步改善,大气污染治理的复杂程度持续增加. “十四五”时期明确要求“加强PM2.5和臭氧协同控制”,对大气污染精细化治理和管控提出更高要求,而发掘具有源示踪特征的有机化合物对于解析污染来源、实现精细化管控具有重要意义. 有机化合物是大气细颗粒物(PM2.5)中最主要的组分之一,其来源多样,化学成分复杂. 目前,大气细颗粒物中已鉴定的有机物有烷烃、烯烃、芳香烃、糖醇等[1],其中一些具有源指示特性的化合物已应用于大气细颗粒物来源解析,如多环芳烃(PAHs)[2]、正构烷烃[3],但样品中仍有大量有机物尚未被鉴别.
质谱检测技术的发展使大气细颗粒物中未知有机物的定性筛查与半定量分析成为可能[4 − 8]. 马英歌等[6]采用高压溶剂萃取-气相色谱/质谱技术,在无标准品条件下对3个不同季节PM2.5样品进行有机污染物的定性和半定量分析,检出17种有机物,其中以邻苯二甲酸酯(PAEs)为主的酞酸酯检出率高,正构烷类和多环芳烃类次之. 范军等[4]利用全二维气相色谱/质谱技术在PM2.5样品中检出烷烃、烯烃、多环芳烃等有机物. 曾源等[7]对广州主要城区、企业和市政设施周边PM2.5样品中检出增塑剂、正构烷烃、阻燃剂、农药等161种有机物. Duong等[8]利用目标物筛查方法和GC-MS数据库在越南河内大气颗粒物中检出了包括多环芳烃、杀虫剂、内分泌干扰物、药物和个人护理品、甾醇类、增塑剂、有机磷阻燃剂在内的118种有机物. 这些研究表明大气细颗粒物中存在大量不同种类有机物,对其中尚未被鉴定的有机物开展定性研究,挖掘有源示踪意义的有机物,对深入开展大气细颗粒物来源解析具有重要意义.
气相色谱-四极杆飞行时间质谱(GC-QTOF/MS)技术具有高分辨率、高准确度等特点,在未知物定性分析和筛查方面有很大优势. 目前,GC-QTOF/MS技术在果蔬农残、尿液中兴奋剂、土壤中PAHs和农残检测等方面的应用较多[9 − 11],而在大气中有机物,尤其是细颗粒物中有机物的定性筛查研究较少[5]. 徐婷婷等[5]用GC-QTOF/MS在气溶胶颗粒上鉴别出烷烃、藿烷、酮、多环芳烃、含氧多环芳烃、酯和杂环化合物等有机物. 将GC-QTOF/MS技术用于大气细颗粒物中有机物的定性筛查,有助于探明大气细颗粒物污染来源,为污染物控制清单和定量方法的建立提供技术支撑. 本文基于GC-QTOF/MS对大气PM2.5样品中的有机物开展定性筛查,并对识别的化合物进行定量和半定量分析,为进一步研究污染源有机示踪物及大气细颗粒物精细化来源解析提供研究基础.
GC-QTOF/MS对大气细颗粒物中有机物的筛查
Screening analysis of organic compounds in ambient fine particulate matter by gas chromatography-quadrupole time-of-flight mass spectrometry
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摘要: 本文基于气相色谱-四极杆飞行时间质谱(GC-QTOF/MS)技术对大气细颗粒物中的有机物进行定性筛查及半定量分析. 通过高分辨质谱数据库和NIST标准质谱库,在大气细颗粒物样品中识别出180余种有机物,包括多环芳烃、甲基多环芳烃、含氧多环芳烃、芳香酯、脂肪酸酯、烷醇等. 样品中有机物浓度在126.9—774.3 ng·m−3,其中24种定量的多环芳烃浓度在12.6—203.4 ng·m−3,占总浓度的10%—26%,其他多环芳烃及多环芳烃衍生物浓度为17.7—103.0 ng·m−3,芳香酯浓度为25.9—104.4 ng·m−3,脂肪酸酯浓度为9.0—65.8 ng·m−3. 此外,棕榈酸、二苯砜、左旋葡聚糖、萘二甲酸酐、十八烷酸、十二碳醇酯、蒽醌、芥酸酰胺的浓度也较高,分别为7.5—36.8、11.4—30.7、7.7—19.4、3.7—18.0、3.5—17.6、8.7—14.7、3.4—12.3、7.1—19.5 ng·m−3. 样品中有机物总浓度随PM2.5、PM2.5中OC浓度的增加而增加,且具有较好相关性. 研究结果显示,GC-QTOF/MS在大气细颗粒物有机物的定性筛查及半定量方面具有很大优势,本研究可为开展污染源废气及颗粒物中有机物的筛查,全面掌握大气污染来源及特征提供技术支撑.
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关键词:
- 大气细颗粒物 /
- 气相色谱-四极杆飞行时间串联质谱 /
- 定性及半定量分析
Abstract: Based on the gas chromatography-quadrupole time-of-flight tandem mass spectrometry (GC-QTOF/MS) technology, qualitative and semi-quantitative screening analysis of organic compounds in ambient fine particulate matter samples was conducted. By using the high-resolution mass spectrometry database and the NIST standard mass spectrum database, more than 180 organic compounds were identified in the fine particulate matter samples, including polycyclic aromatic hydrocarbons (PAHs), methyl polycyclic aromatic hydrocarbons, oxygenated polycyclic aromatic hydrocarbons, aromatic esters, fatty acid esters, alkanols, etc. The concentration of organic compounds identified in the samples were 126.9—774.3 ng·m−3, and the concentration of 24 PAHs were 12.6—203.4 ng·m−3, accounting for 10%—26% of the total concentration. The concentrations of other PAHs and their derivatives were 17.7—103.0 ng·m−3, the concentrations of aromatic esters were 25.9—104.4 ng·m−3, and the concentrations of fatty acid esters were 9.0—65.8 ng·m−3. Moreover, the concentrations of palmitic acid, diphenyl sulfone, levoglucosan, naphthalic anhydride, octadecanoic acid, 2-methyl-propanoic acid-3-hydroxy-2,2,4-trimethylpentyl ester, anthraquinone, (Z)-13-docoxsenamide were also higher, which were 7.5—36.8, 11.4—30.7, 7.7—19.4, 3.7—18.0, 3.5—17.6, 8.7—14.7, 3.4—12.3, 7.1—19.5 ng·m−3, respectively. The total concentration of organic matter identified in the samples increased with the increase of the concentration of PM2.5 and organic carbon (OC) concentration in PM2.5. The results show that GC-QTOF/MS has great advantages in the qualitative screening and semi-quantitative analysis of organic matter in ambient fine particulate matter. This study can provide technical support for conducting the screening of organic matter in waste gases and particulate matter from pollution sources, and comprehensively grasping the sources and characteristics of atmospheric pollution. -
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