Yassine Mahmoud M, Dabek-Zlotorzynska Ewa
Analysis and Air Quality Section, Air Quality Research Division, Atmospheric Science and Technology Directorate, Science and Technology Branch, Environment and Climate Change Canada, Ottawa, Ontario K1A 0H3, Canada.
Analysis and Air Quality Section, Air Quality Research Division, Atmospheric Science and Technology Directorate, Science and Technology Branch, Environment and Climate Change Canada, Ottawa, Ontario K1A 0H3, Canada.
J Chromatogr A. 2017 Aug 25;1512:22-33. doi: 10.1016/j.chroma.2017.06.067. Epub 2017 Jun 28.
Naphthenic acids (NAs) are naturally occurring constituents of hydrocarbon deposits (petroleum, oil sands bitumen, and crude oils), and present in any facilities that extract, process or use crude oil or bitumen for manufacturing. In the Athabasca oil sands region (AOSR) of Alberta, Canada, this diverse group of saturated acyclic, monocyclic, and polycyclic carboxylic acids is present in bitumen and in tailing ponds. Little is known about the occurrence of residual oil sands derived organic material, including NAs, in atmospheric particulate matter (PM). This work describes the optimization of an ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/QTOF-MS) method to characterize and identify classical NAs in atmospheric PM. Under the optimum conditions, analysis of the Sigma-Aldrich technical NA STD Mix showed the absence of saturated fatty acids, while branched and cyclic NAs isomers with carbon number ranged between 10 and 30, and Z families between 0 and -12 were detected. Higher molecular weight NAs representing compounds with carbon number ranging between 30 and 40 were identified in the analyzed PM samples collected in AOSR. In contrast, isomeric branched acyclic NAs were not detected in the background (PM-R) samples collected far from AOSR. Except for fatty acids (Z=0), other Z homologues were also not detectable or present at very low concentration in the analysed PM-R samples. Preliminary examination of NA profiles showed that the composition of NAs in PM collected in close proximity to surface mining operations is predominantly "refractory" high molecular weight branched NAs, differing from that collected closer to upgraders and tailings ponds. It is suspected that dust released from the mine faces and dry tailings in the AOSR are sources of NAs to atmosphere. Further samples should be examined to confirm findings. This preliminary study presents, to our knowledge, the first direct identification of branched acyclic and cyclic NAs in atmospheric PM.
环烷酸（NAs）是烃类沉积物（石油、油砂沥青和原油）中的天然成分，存在于任何提取、加工或使用原油或沥青进行制造的设施中。在加拿大阿尔伯塔省的阿萨巴斯卡油砂地区（AOSR），这类多样的饱和无环、单环和多环羧酸存在于沥青和尾矿池中。关于大气颗粒物（PM）中残留油砂衍生有机物质（包括NAs）的存在情况知之甚少。这项工作描述了一种超高效液相色谱 - 四极杆飞行时间质谱（UPLC/QTOF-MS）方法的优化，以表征和鉴定大气PM中的典型NAs。在最佳条件下，对西格玛 - 奥德里奇技术NA标准混合物的分析表明不存在饱和脂肪酸，同时检测到碳数在10至30之间的支链和环状NAs异构体，以及Z值在0至 -12之间的异构体。在AOSR采集的分析PM样品中鉴定出了代表碳数在30至40之间的化合物的更高分子量NAs。相比之下，在远离AOSR采集的背景（PM-R）样品中未检测到异构支链无环NAs。除了脂肪酸（Z = 0）外，其他Z同系物在分析的PM-R样品中也未检测到或浓度极低。对NA谱的初步检查表明，在靠近露天采矿作业处采集的PM中，NAs的组成主要是“难熔的”高分子量支链NAs，与在靠近升级装置和尾矿池处采集的不同。怀疑AOSR中矿面和干尾矿释放的灰尘是大气中NAs的来源。应检查更多样品以确认研究结果。据我们所知，这项初步研究首次直接鉴定了大气PM中的支链无环和环状NAs。
