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首页> 外文会议>International symposium on the measurement of toxic and related air pollutants >Sample Integrity of Volatile Organic Compounds Collected and Stored on Multiadsorbent Tubes and Analyzed Using an AutoGC-MS System
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Sample Integrity of Volatile Organic Compounds Collected and Stored on Multiadsorbent Tubes and Analyzed Using an AutoGC-MS System

机译：收集和存储在多吸附管上并使用AutoGC-MS系统分析的挥发性有机化合物的样品完整性

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Solid sorbents were used to collect and store 40 of the 41 volatile organic compounds (VOCs)rnlisted in EPA Compendium Method TO-14. Storage time was varied from 0 to 30 days, afterrnwhich a gas chromatography (GC)–mass spectrometry (MS) analysis was performed to determinernany losses of target compounds. Two commercially available multisorbent combinations packedrnin 90-mm by 4-mm-i.d. glass tubes were investigated in detail. The first multisorbentrncombination was 160 mg Carbotrap B and 70 mg Carboxen 1000; the second multisorbentrncombination was 175 mg Anasorb GCB1 and 180 mg Anasorb CMS. The 0.5- to 20-ppbv TO-14rnsamples used in the evaluation were generated synthetically by blending a 2-ppmv TO-14rncompound mixture with humidified scientific-grade air in a dynamic dilution manifold. Thernsorbent tubes were then loaded from the dilution manifold with sample volumes of .25, 1, or 4 Lrnof the low-ppbv TO-14 mixture to duplicate field sample collection procedures. This samplernloading procedure is more realistic than the technique of syringe-spiking sorbent tubes with highrnconcentrations of VOCs that is often employed in sorbent storage stability studies. The use ofrndistributed volume sampling (two tubes loaded over the same time period at different samplingrnrates) was effective in providing a minimum level of quality assurance. The analysis of samplesrnwas performed using a Perkin Elmer Model ATD 400 automated thermal desorption unit, arnVarian Star 3400Cx gas chromatograph, and a Varian Saturn 2000 ion trap mass spectrometer.rnThe sample tubes were heated to desorb the VOCs, which were then flushed from the tube by arnflow of helium and collected on a multisorbent trap. The trap contained less sorbent than thernsample tube and was effective in subsequently releasing the compounds, again by thermalrndesorption, in a small volume to the GC-MS.rnExperiments in the sample integrity study included preliminary tests investigating sample loadingrnprocedures, tube purging, and comparison of distributive volume pairs; breakthroughrnexperiments; determination of method detection limits (MDLs); determination of precision;rnsample integrity studies; humidity tests; ozone experiments; and collection of ambient airrnsamples. The Carbotrap B/Carboxen 1000 sorbent combination proved to be the mostrnsatisfactory for use with the TO-14 compound set. This multisorbent combination exhibited arnlow background and low variability in response of compounds collected and desorbed from it.rnThe TO-14 MDLs for this combination ranged from 0.04 to 0.51 ppbv except for bromomethane,rnwhich was 1.25 ppbv, and chloromethane, which was 1.37 ppbv. Results of the 30-day studyrnshowed 30-day recoveries within ±20% for loading levels of 5 ppbv with the followingrnexceptions: (1) chloromethane, vinyl chloride, bromomethane, and chloroethane, which werernrecovered at less than 80% at any storage time; (2) 3-chloropropene, which was recovered at lessrnthan 80% after 1 week; (3) 1,1-dichloroethene and dichloromethane, which were recovered atrnless than 80% by day 15; and (4) cis-1,2-dichloroethene and trichloromethane, which were
机译：固体吸附剂用于收集和存储EPA简编方法TO-14中列出的41种挥发性有机化合物（VOC）中的40种。储存时间从0天到30天不等，然后进行气相色谱（GC）-质谱（MS）分析以确定目标化合物的损失。两种市售的多吸附剂组合以90毫米x 4毫米内径包装。玻璃管进行了详细研究。第一种多吸附剂组合是160 mg Carbotrap B和70 mg Carboxen 1000；第二种多吸附剂组合为175 mg Anasorb GCB1和180 mg Anasorb CMS。评估中使用的0.5至20 ppbv的TO-14rn样品是通过在动态稀释歧管中将2 ppmv的TO-14rn化合物混合物与加湿的科学级空气混合而生成的。然后从稀释歧管中向吸附管中加载0.25、1或4 Lrnof的低ppbv TO-14混合物样品，以重复进行现场样品收集程序。该样品加载程序比通常在吸附剂存储稳定性研究中采用的高浓度VOC的针刺吸附剂管技术更为现实。使用分布式体积采样（在相同的时间段内以不同的采样率加载两个试管）有效地提供了最低水平的质量保证。样品分析使用Perkin Elmer ATD 400型自动热脱附装置，arnVarian Star 3400Cx气相色谱仪和Varian Saturn 2000离子阱质谱仪进行.rn加热样品管以解吸VOC，然后将其从管中冲洗掉通过氦的气流，收集在多吸附阱上。捕集阱的吸附剂比样品管少，并且可以有效地随后通过热解吸将化合物再次释放到小体积的GC-MS中。样品完整性研究中的实验包括初步测试，以调查样品加载过程，试管清洗以及对样品的比较。分配卷对；突破性实验确定方法检测限（MDL）；精度测定;样品完整性研究;湿度测试；臭氧实验；并收集周围空气样本。事实证明，Carbotrap B / Carboxen 1000吸附剂组合最适合与TO-14化合物组合使用。这种多吸附剂组合物表现出较低的背景，并且对从中收集和解吸的化合物的响应变化很小。rn该组合物的TO-14 MDL值范围为0.04至0.51 ppbv，其中溴甲烷为1.25 ppbv，氯甲烷为1.37 ppbv。 30天的研究结果表明，在5 ppbv的装载量下，其30天的回收率在±20％之内，以下情况除外：（1）氯甲烷，氯乙烯，溴甲烷和氯乙烷，在任何储存时间回收率均低于80％； （2）3-氯丙烯，在1周后回收率低于80％； （3）1,1-二氯乙烯和二氯甲烷，到第15天的回收率均不低于80％； （4）顺式1,2-二氯乙烯和三氯甲烷，分别为

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