共查询到20条相似文献，搜索用时 62 毫秒
1.
新型固相微萃取装置的研制及在有机磷农药检测中的应用 总被引：2，自引：2，他引：0
使用有机磷农药引起的环境污染问题日益严重,建立针对水体中有机磷农药的快速、灵敏、准确的检测方法,具有重要意义。文章采用溶胶-凝胶法自制一种有机-无机杂化涂层固相微萃取(SPME)探头,探头涂层呈多孔状。同时取用廉价易得的气相色谱进样针,设计了一种新的SPME装置。研究了SPME-GC/MS同时测定环境水样中甲拌磷、乙拌磷、甲基对硫磷、对硫磷、水胺硫磷5种有机磷农药的分析方法。方法检出限为1.2~3.9 μg/L,相对标准偏差(RSD, n=6)为0.8%~7.4%。通过对实际样品的分析,方法加标回收率为93%~112%。建立的分析方法适合于环境水样中痕量有机磷农药的快速分析,具有一定的实用价值和应用前景。自制的有机-无机杂化涂层探头能重复使用达100余次,性能优于商用聚丙烯酸脂和聚二甲基硅氧烷涂层的萃取效果,通过更换探头,装置可重复使用。 相似文献
2.
多环芳烃(PAHs)是一类具有致癌作用且难以降解的持久性有机污染物,广泛存在于环境中。环境中痕量PAHs的直接分析往往因检测手段的检出限达不到要求而存在困难,需要结合分离富集手段。常规的样品前处理技术如索氏提取、液液萃取等存在耗时长、使用大量有机溶剂等问题。因此为了提高效率、避免对自然环境的二次污染,有必要开发一种简便、环境友好的新型样品前处理技术。固相微萃取(SPME)是一种集采样、富集、进样于一体的无溶剂前处理技术,与气相色谱-质谱(GC-MS)等技术联用可实现复杂基质中痕量有机物的快速富集和检测。目前SPME技术的研究热点主要集中在改善涂层的萃取性能以及提高其机械强度方面。本文采用铁丝(IW)作为载体,同时又提供了铁离子来源,以原位自转化的方式在具有良好机械稳定性的铁丝上生长出一层多孔结构的金属有机骨架化合物多孔膜[MIL-53(Fe)];将其作为固相微萃取涂层[IW@MIL-53(Fe)],以7种难挥发的稠环PAHs作为目标分析物,以浸入式模式进行萃取,并结合GC-MS作为检测手段验证其萃取性能。结果表明:新涂层的萃取性能是商用100μm PDMS涂层的1～2倍,且涂层可稳定使用120次以上。该方法的检出限为0.03～2.25ng/L,线性范围为250～10000ng/L,相关系数为0.9903～0.9991。将建立的方法应用于自然水体中PAHs的检测,加标回收率为80.1%～108.5%。本研究不仅为高性能SPME涂层简单、快速制备提供了新思路,而且所建立的方法有望应用于水体中痕量有机污染物的准确和高灵敏检测。 相似文献
3.
尿素络合法分离-气相色谱/同位素质谱法分析土壤和植物中低含量(ppm级)正构烷烃的碳同位素 总被引：1，自引：1，他引：0
尿素络合法和5A分子筛法是常用的分离富集环境样品中正构烷烃的方法,但由于复杂的处理流程对于低含量正构烷烃的回收率普遍较低。本文通过优化尿素络合法分离富集正构烷烃的实验条件,建立了尿素络合法分离-气相色谱/同位素质谱分析土壤和植物中低含量正构烷烃单体碳同位素的方法。即采用正己烷-丙酮溶解样品,在4℃冰箱中与2 m L尿素-甲醇饱和溶液反应48 h;用去离子水溶解尿素络合物,加入正己烷后分离出有机相和水相,分别用正己烷、丙酮-正己烷萃取有机相和水相中的正构烷烃。中长链正构烷烃的回收率达79%~104%,高于5A分子筛法和已有尿素络合法的富集效果;单体碳同位素的分析精度为0.09‰~0.63‰(1σ)。利用改进的方法分析实际样品,大幅降低了未分峰和共流出物的干扰,提高了实际样品中ppm级中长链正构烷烃的回收率。 相似文献
4.
应用气相色谱-气体同位素质谱(GC-C-IRMS)分析正构烷烃单体碳同位素之前,需要对饱和烃样品中正构烷烃和异构烷烃进行预分离、富集,在预分离和富集过程中正构烷烃单体碳同位素是否发生分馏是高精度分析正构烷烃单体碳同位素比值(δ~(13)C)的关键。本文以正构烷烃混合溶液为对象,利用柱色谱、5■分子筛络合、环己烷-正戊烷混合溶剂两次洗脱,GC-C-IRMS分析正构烷烃单体碳同位素,研究前处理过程中正构烷烃单体碳同位素是否发生分馏。结果表明:使用柱色谱分离前后,多数正构烷烃单体碳同位素比值相差-0.2‰～0.2‰;当5■分子筛不完全络合时,未络合的正构烷烃单体碳同位素比值偏重约0.7‰,可能发生了微弱的碳同位素分馏,但并未影响洗脱后的正构烷烃单体碳同位素比值;使用环己烷-正戊烷混合溶剂洗脱前后,碳同位素比值相差-0.2‰～0.5‰,以同样方式洗脱第二次,获得的正构烷烃单体碳同位素比值与模拟样品相差-0.3‰～0.2‰。分析不同回收率(20%)正构烷烃的单体碳同位素比值,处理前后的差值基本在0.3‰以内,可见当正构烷烃回收率低至20%左右时,其单体碳同位素仍未发生明显分馏。柱色谱分离-5■分子筛络合-混合溶剂洗脱方法适用于回收率大于20%的正构烷烃单体碳同位素分析。 相似文献
5.
气相色谱-串联质谱技术分析地质调查植物样品中持久性有机污染物的优势 总被引：1，自引：0，他引：1
对于复杂基质的样品,采用气相色谱法、气相色谱-质谱法( GC - MS)不能满足当前痕量水平分析的要求,串联质谱已发展成一种有机分析测试的成熟技术可应用于地质调查样品分析.本文建立了气相色谱-串联质谱技术( GC - MS - MS)分析植物样品中有机氯农药及多氯联苯的方法,通过对植物样品(圆白菜、菠菜、胡萝卜、橘子)分析,系统比较了GC- MS-MS与气相色谱-电子捕获检测器(GC-ECD)和气相色谱-选择离子-质谱( GC - SIS - MS)三种分析技术的检出限、定性定量分析结果,确认了分析方法的适用性.GC- MS-MS方法的检出限为0.03～0.29 ng/g,大部分化合物均低于GC -ECD的检出限,是GC - SIS -MS检出限的0.4倍.GC- MS-MS分析表明,圆白菜不含反式-氯丹,排除了GC-ECD的假阳性检出;检测胡萝卜等基质复杂、净化困难的样品,GC- MS-MS也表现出良好的定性定量能力;检出低含量水平样品菠菜含有0.26 ng/g六氯苯,而气相色谱未检出,表明GC- MS-MS显著提高了分析灵敏度,能够对样品中低含量的化合物进行准确定量.在三种分析技术中,GC- MS-MS在样品的准确定性、复杂基质样品分析灵敏度、低含量水平准确定量等方面都具有独特的优势,同时能够应用于复杂样品检测结果的确证. 相似文献
6.
水体中痕量挥发性有机物单体碳同位素组成的固相微萃取-冷阱预富集GC-IRMS分析 总被引：1，自引：0，他引：1
单体碳同位素分析是进行污染物来源判识与过程示踪的有力工具 ,然而有机污染物浓度低、难以萃取富集 ,极大地限制了该技术的广泛应用 .采用固相微萃取 -冷阱富集GC -IRMS技术对水中痕量挥发性有机物进行了单体碳稳定同位素分析 ,样品经SPME萃取富集后在色谱进样口冷冻成形 ,样品多次进样得以累积从而满足了检测限的要求 .本方法检出限较目前文献所报道的SPME方法提高了 1个数量级 .在优化的条件下 ,对低浓度的三氯乙烯、四氯乙烯、苯以及甲苯的水溶液进行了单体碳同位素组成测定 ,测定结果与纯液相中的同位素值相比 ,同位素分析误差不超过 0 .5× 10 -3 ,而分析的精度达到± 0 .3× 10 -3 .固相微萃取 -冷阱富集可以提供高效准确的单体碳同位素分析 ,该方法适用于水体中痕量挥发性有机污染物的同位素组成测定 . 相似文献
7.
利用5A分子筛吸附,环己烷-正戊烷混合溶剂洗脱分离富集正构烷烃,用气相色谱法测定正构烷烃含量,气相色谱-气体同位素质谱(GC-C-IRMS)测定土壤样品中正构烷烃单体碳同位素。实验优化了5A分子筛用量和洗脱剂的比例,需要络合的正构烷烃的量与分子筛加入量呈线性关系,络合x mg的正构烷烃,需加入2.75x g分子筛,络合环己烷-正戊烷最佳比例为9∶91。探讨了络合过程中5A分子筛对不同链长正构烷烃的络合规律,短链正构烷烃被5A分子筛优先吸附,长链正构烷烃的络合相对滞后。正构烷烃的络合洗脱回收率为44%～72%,精密度(RSD,n=6)为4%～8%;正构烷烃单体碳同位素分析精度为0.04‰～0.38‰(1σ)。采用5A分子筛净化混合溶剂洗脱方法,分析加油站附近的实际土壤样品,未分峰基本消除,获得良好的净化效果,满足正构烷烃单体碳同位素分析的要求。 相似文献
8.
顶空进样-固相微萃取测定饮用水源水中吡啶 总被引：2，自引：1，他引：1
用75μm CarboxenTM-Polydimethylsiloxane(CAR-PDMS)固相微萃取头顶空萃取15 mL水样中的吡啶,萃取物用气相色谱-质谱法进行分离和检测,采用内标法和质谱的选择离子监测模式进行定量分析。优化了顶空进样-固相微萃取条件,获得较佳的萃取温度(58.0℃)和萃取时间(40 min)。在优化的条件下,方法检出限为1.5μg/L,标准曲线的线性相关系数为0.9994,线性范围为2.5～50.0μg/L;饮用水源水和纯水加标平均回收率为75.6%～81.3%,相对标准偏差(RSD,n=6)为9.60%～12.21%。使用顶空萃取方式可避免样品基体的复杂性,有利于保护萃取头涂层,同时无需使用有机萃取溶剂;使用质谱检测器可减小假阳性带来的影响。顶空进样-固相微萃取操作简单、环保、灵敏度高,适合用于饮用水源水中吡啶的监测分析。 相似文献
9.
用于单体氢同位素分析的混合溶剂洗脱5分子筛吸附正构烷烃的方法 总被引：1，自引：1，他引：0
混合溶剂萃取洗脱5分子筛吸附正构烷烃的方法在单体碳同位素分析研究中已得到了应用。由于5分子筛在长时间加热条件下可能对有机分子的氢交换反应具有一定的催化作用,因此对于该方法能否用于正构烷烃的单体氢同位素分析需要做进一步研究。本文以两种不同类型原油的饱和烃和正构烷烃混合标准样品为对象,采用环己烷-正戊烷溶剂和氢氟酸溶解-正戊烷溶剂洗脱5分子筛吸附的正构烷烃,对比分析两种萃取方式的分离效果,并分别测定了正构烷烃的单体氢同位素比值。结果表明:两种萃取方式都得到了纯化效果良好的正构烷烃组分,氢同位素测定结果的差值总体上小于4‰,在仪器分析误差范围内。经过三次环己烷-正戊烷洗脱方式获得正构烷烃回收率平均值为58%,氢氟酸溶解-正戊烷洗脱方式经过多次萃取操作获得正构烷烃回收率平均值为68%。尽管环己烷-正戊烷洗脱方式提取正构烷烃的效率较低,并且涉及在分子筛条件下多次较长时间的加热过程,但这两个因素没有导致氢同位素发生明显的分馏或交换过程,适合用于正构烷烃分离、纯化以及单体氢同位素测定。 相似文献
10.
加速溶剂萃取提取土壤中正构烷烃的方法研究 总被引：6，自引：4，他引：2
建立了加速溶剂萃取技术提取-柱色谱分离-气相色谱分析土壤样品中正构烷烃的方法。优化了压力、温度、静态时间、循环次数等参数。随着温度、静态时间、循环次数和压力的增加,正构烷烃短碳链、长碳链和总正构烷烃的量逐渐增加。加速溶剂萃取提取土壤中正构烷烃的条件是:萃取温度150℃,萃取压力10.3 MPa,循环2次,静态提取时间10 min。加速溶剂萃取-柱色谱分离-气相色谱法测定土壤中正构烷烃的方法精密度(RSD)为8%~23%。加速溶剂萃取法提取总正构烷烃量、短碳链正构烷烃量显著高于索氏抽提法的提取量。 相似文献
11.
The origin of the genus Bos is a debated issue. From ∼ 0.5 Ma until historic times, the genus is well known in the Eurasian large mammal assemblages, where it is represented by Bos primigenius. This species has a highly derived cranial anatomy that shows important morphological differences from other Plio-Pleistocene Eurasian genera of the tribe Bovini such as Leptobos, Bison, Proamphibos-Hemibos, and Bubalus. The oldest clear evidence of Bos is the skull fragment ASB-198-1 from the middle Pleistocene (∼ 0.6-0.8 Ma) site of Asbole (Lower Awash Valley, Ethiopia). The first appearance of Bos in Europe is at the site of Venosa-Notarchirico, Italy (∼ 0.5-0.6 Ma). Although the origin of Bos has traditionally been connected with Leptobos and Bison, after a detailed anatomical and morphometric study we propose here a different origin, connecting the middle Pleistocene Eurasian forms of B. primigenius with the African Late Pliocene and early Pleistocene large size member of the tribe Bovini Pelorovis sensu stricto. The dispersal of the Bos lineage in Western Europe during middle Pleistocene times seems to coincide with the arrival of the Acheulean tool technology in this continent. 相似文献
12.
New records of Jefferson's ground sloth (Megalonyx jeffersonii) and elk-moose (Cervalces scotti) from Lang Farm provide the first precise temporal correlation of these taxa with the specific environments inhabited by them near the time of their extinction. Six AMS 14C measurements establish an age of 11,405 ± 50 14C yr B.P. for Lang Farm Cervalces and an age of 11,430 ± 60 or 11,485 ± 40 14C yr B.P. for the Megalonyx. These measurements represent the youngest 14C dates for these two genera based on direct dating. Comparison of the dates with pollen data from northern Illinois indicates that these species inhabited a nonanalog environment that was transitional from mid-latitude tundra to mixed conifer and deciduous woodland. Although spruce (Picea sp.) was dominant, it was less abundant than prior to 12,500 14C yr B.P. The presence of black ash (Fraxinus nigra) and fir (Abies sp.) indicates a wet climate and heavy winter precipitation. This may have been the preferred habitat for Cervalces because of its narrow geographic range. However, this habitat type was only one of many occupied by Megalonyx as indicated by its broad geographic distribution. 相似文献
13.
Stephen K. Donovan James Isted 《Proceedings of the Geologists' Association. Geologists' Association》2014
Nineteenth-century references to clavate borings in woody substrates in the Lower Greensand of the Isle of Wight used a variety of names, but Teredo (a wood-boring bivalve, not a boring), Teredolithes (a junior synonym of Teredolites) and Gastrochaena (a bivalve borer of rock and shelly substrates, not a boring in wood) are all nomenclatorially incorrect. Borings in a beach clast derived from the Lower Greensand Group and recently collected from Sandown Bay, Isle of Wight, are referred to Teredolites isp. cf. T. longissimus Kelly and Bromley. This specimen confirms the presence of Teredolites in the Lower Greensand Group and demonstrates a common ichnological problem of beach clasts; borings, either fossil or modern, are incompletely preserved, making confident classification below the level of ichnogenus problematic. 相似文献
14.
原位U-Th/He同位素定年技术研究进展及其低温矿床学应用前景 总被引：2，自引：1，他引：1
应用传统单颗粒方法对目标矿物进行定年具有较高要求(如U、Th等母体同位素均匀分布),需要耗时的酸溶过程,同时还需进行α粒子射出效应校正。原位U-Th/He同位素定年技术是近年发展起来的一种定年技术,其主要原理是采用激光加热目标矿物,并通过与激光系统连接的稀有气体质谱(Alphachron)和电感耦合等离子体质谱(ICP-MS)分别完成 ~4He和U、Th等母体同位素分析,将 ~4He和U、Th分析结果代入年龄公式计算即可获得目标矿物的U-Th/He年龄。本文阐述了原位U-Th/He同位素定年技术的主要原理、实验测试流程、适用矿物等,重点对原位U-Th/He同位素定年的技术难点和低温矿床学应用前景进行了分析。相对于传统单颗粒方法,原位测试方法解决了两个关键问题:1无需进行α粒子射出效应的校正,提高了定年结果的可靠性和准确度;2能完成母体同位素分布不均匀样品的测试,扩展了U-Th/He同位素定年的应用范围。尽管原位U-Th/He同位素定年技术在侧向加热效应、剥蚀坑体积测定以及标准矿物等方面尚存在一些亟待解决的问题,但已在硅酸盐、磷酸盐、钛铁氧化物等矿物的年代学研究方面展示了良好的应用前景。随着原位U-Th/He同位素定年技术的发展和进步,尤其是硫化物的U-Th/He同位素定年的发展,将为解决低温矿床的年代学问题提供一种新的思路。 相似文献
15.
Given the difficulty of separating the three Picea species—P. glauca, P. mariana, and P. rubens (white, black, and red spruce)—in the pollen record, little is known about their unique histories in eastern North America following deglaciation. Here we report the first use of a classification tree analysis (CART) to distinguish pollen grains of these species. It was successfully applied to fossil pollen from eight sites in Maine and one in Massachusetts. We focused on the late glacial/early Holocene (14,000 to 8000 cal yr B.P.) and the late Holocene (1400 cal yr B.P. to present)—the two key periods since deglaciation when Picea has been abundant in the region. The result shows a shift from a Picea forest of P. glauca and P. mariana in the late glacial to a forest of P. rubens and P. mariana in the late Holocene. The small number of P. rubens grains identified from the late glacial/early Holocene samples (<5%) suggests that that species was either absent or rare at most of the sites. The occurrence and distribution of the three species do not reveal any geographic or temporal trend during late glacial time, but the data suggest that they were distributed in local patches on the landscape. The results of this study indicate that the recent population expansion of Picea (1000 to 500 cal yr B.P.) was likely the first time since deglaciation that P. rubens was abundant in the region. 相似文献
16.
Michael E. Burns Philip J. CurrieRobin L. Sissons Victoria M. Arbour 《Cretaceous Research》2011,32(2):174-186
Four juvenile specimens referable to Pinacosaurus grangeri (Ankylosauria: Dinosauria) are described from the Campanian (Upper Cretaceous) locality Bayan Mandahu in northern Inner Mongolia Autonomous Region (People’s Republic of China). All the specimens preserve the skulls as well as, in some cases, mandibles, postcrania, and osteoderm. They are not taphonomically deformed by expanding matrix distortion, unlike many Gobi specimens, including the holotype of P. grangeri. Bayan Mandahu is also the type locality for Pinacosaurus mephistocephalus. The proximity in space and time of these two closely related species warrants a generic and specific revision for Pinacosaurus. The distinction of the two species is based on characters of the squamosal dermal elaborations, cranial roof posterior to the orbits, premaxillary notch, and distal margin of the ilium. Although a relatively well-represented ankylosaur taxon, the phylogenetic position of Pinacosaurus has not been unequivocally resolved. A new analysis recovers Pinacosaurus as the most basal member of the Ankylosaurinae. 相似文献
17.
The identification of fossil pollen at the generic rather than species level is hampering progress in understanding the biogeography and dynamics of paleo-vegetation. We used CART analysis to facilitate the differentiation of fossil pollen of Pinus banksiana and Pinusresinosa, which are morphologically similar and nearly always combined in paleoecological studies. The CART model, using four of the ten morphological traits measured, exhibited a high level of correct identification for pollen of each of the species and shows promise as a tool for increasing the detail of paleoecological records and inferences. 相似文献
18.
William T. Blows Kerri Honeysett 《Proceedings of the Geologists' Association. Geologists' Association》2014
A new partial skeleton of the armoured ornithischian dinosaur Polacanthus found in the Wadhurst Clay Formation (Valanginian stage) of Bexhill, Sussex is the oldest recorded occurrence of this taxon. Previous discoveries suggested that at least two armoured ornithischians occur in the Wealden succession: Polacanthus, which was mostly restricted to the Barremian, and Hylaeosaurus, which was recorded as present only in the Valanginian. The new discovery extends the stratigraphic range of Polacanthus into the Valanginian. Although these two taxa appear to be closely similar anatomically, their osteology now suggests they are not synonymous. The new specimen includes the first known jugal as well as a comparatively rare polacanthid plate/spine (splate) which probably comes from the shoulder (pectoral) area of these animals. 相似文献
19.
本文从携带式X射线荧光仪器、现场分析技术和技术应用三方面论述了现场X射线荧光分析技术的进展.从X射线激发源、X射线探测器和电子线路单元等角度,将携带式X射线荧光仪划分为四代,即以放射性同位源为激发源、以NaI(Tl)闪烁计数器为X射线探测器为技术特征的第一代仪器;以放射性同位素源和正比计数器为技术特征的第二代仪器;以放射性同位素、电制冷半导体探测器和以嵌入式微处理器为控制核心的多道脉冲幅度分析器为技术特征的第三代仪器;以低功率微型X射线发生器为激发源、电制冷半导体探测器和全数字化X射线能谱采集器为技术特征的第四代仪器.在现场分析技术方法方面,论述了X射线仪器谱解析技术、基体效应校正技术和现场原位分析中不平度效应、湿度效应、荧光颗粒不均匀效应校正技术进展.介绍了现场X射线荧光分析技术在地质矿产普查、环境污染调查、文物现场鉴定和合金分析等领域的应用进展.指出了目前国产携带式X射线荧光仪处于第三代和第四代仪器水平之间,低功率微型X射线发生器和电制冷半导体探测器还依赖于进口,全数字X射线能谱采集器还有待商品化;现场多元素分析的准确度和方法检出限都有待进一步改善;便携式仪器的应用领域有待拓宽. 相似文献
20.
本文在对普通培养条件下异养微生物粪产碱杆菌(Alcaligenes faecalis,A.faecalis)反硝化特征研究的基础上,运用电化学方法于一定电势下(-0.15 V、-0.06 V、+0.06 V vs.NHE)模拟半导体矿物导带光电子能量,探讨不同能量的光电子对A.faecalis反硝化特性及细胞生长代谢的影响。实验显示,在普通培养条件下,A.faecalis在有氧和无氧环境中均不能还原NO-3,但还原NO-2效果明显。在模拟光电子实验体系中,A.faecalis可在不同电势(-0.15 V、-0.06 V、+0.06 V)的阴极石墨电极表面附着并形成具有反硝化活性的菌膜;其中,外加电势为-0.15V的实验组菌膜量最多,其NO-3去除率也最高,10天达到52%;-0.06 V体系略低,NO-3去除率为30.5%,+0.06 V体系菌膜量最少,其NO-3去除效果也最差,仅为10.6%。而在不添加微生物的电化学体系中,3个外加电势下的NO-3浓度均未发生明显变化。本实验研究结果证明了一定能量的半导体矿物光电子可影响土壤异养微生物A.faecalis的生长代谢及反硝化行为。 相似文献