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Determination of Hydrocarbons in Diesel Exhaust

机译：柴油机中碳氢化合物的测定

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A wide range of sample preparation and analytical methodologies must be employed to fully characterize hydrocarbons in diesel exhaust. Unburnt diesel fuel, diesel oil, particulate-adsorbed combustion products, semi-volatiles, and gaseous combustion products are all organic groupings detectable within an exhaust sample. Each portion has special analytical difficulties that mandate specialized instrumentation to properly identify and quantitate the hydrocarbons. Hydrocarbons emitted by a diesel engine are measured here with several new techniques. Heavier hydrocarbons are trapped as particulates on a quartz filter and a portion of the filter is directly loaded into a modified injection port on a gas chromatograph (GC). Hydrocarbons are rapidly vaporized in this system and transferred quantitatively to the capillary column and detected by mass spectrometry (MS). Species slightly more volatile than those trapped on the filter are ensnared by a combination of polyurethane foam (PUF) and XAD resin adsorbent, then simply extracted and identified by GC/MS. This direct approach eliminates the extensive use of solvents in the sample preparation and significantly reduces the sample preparation time, while also diminishing the risk of contamination or component loss. Spectral interferences are significantly reduced by employing MS/MS, where only the parent ion is initially trapped and then disassociated to yield very selective daughter ions. By performing this logical “AND” selectivity, background interferences are drastically reduced and target hydrocarbons are readily detected. Very light hydrocarbon components, which are not usually trapped by the chosen absorbent media, are collected into Tedlar bags and determined with GC and flame ionization/mass spectrometry detection. Special hardware has been developed to reduce the detection ability of the flame ionization detector.
机译：必须使用各种样品制备和分析方法来完全表征柴油排气中的烃。 Unburnt柴油燃料，柴油，颗粒状吸附燃烧产物，半挥发物和气态燃烧产物是排气样品内可检测到的所有有机分组。每个部分具有特殊的分析困难，该难以授权专门的仪器来正确识别和定量碳氢化合物。用柴油发动机发出的碳氢化合物以几种新技术测量。较重的烃被困为在石英过滤器上的颗粒，并且将一部分过滤器直接装入气相色谱仪（GC）上的改进的喷射口中。烃在该系统中迅速蒸发并定量地转移到毛细管柱中并通过质谱（MS）检测。物种易挥发物体比捕获过滤器上的物种，通过聚氨酯泡沫（PUF）和XAD树脂吸附剂的组合来诱导，然后通过GC / MS简单地提取和鉴定。这种直接方法消除了样品制备中的溶剂广泛使用，并显着降低了样品制备时间，同时还减少了污染或组分损失的风险。通过使用MS / MS显着降低光谱干扰，其中仅母离子是最初被捕获的，然后脱离，以产生非常选择性的子离子。通过执行这种逻辑“和”选择性，背景干扰急剧减少，并且容易检测到目标烃。通常不会被选用的吸收介质捕获的非常轻的烃组分被收集到锥形袋中并用GC和火焰离子化/质谱检测测定。已经开发出特殊的硬件来降低火焰电离检测器的检测能力。

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