GC-MS测定中的小体积样品浓缩技术

在GC-MS仪器分析中,采用窄孔毛细管分析柱(0.25 mm id/0.32.mm id),能引进样品的柱容量很小(约20～60μL气体),为了有效地完成进样过程并获得较高分辨的测定结果(离子色谱图),通常采用的技术主要有柱前"冷聚焦"、柱前分流等,以纯化和减少进样体积,确保进样过程与GC-MS系统的载气流量匹配.     

流动注射-分光光度法测定自来水中游离氯的研究

设计了游离氯流动注射自动在线检测仪,并研究了仪器的最佳测试条件.该仪器采用改进的N,N-二乙基-1,4-苯二胺(DPD)比色原理,通过流动注射进样技术,结合光电转化、数字信号处理及自动化控制技术,克服了DPD分光光度法中手工操作的缺陷,实现了样品分析的自动化.结果证明,此系统的试剂用量少、测定范围宽(0.05～6.00...     

石墨炉原子吸收直接测定原油中痕量钒镍

石墨炉原子吸收光谱 ( GFAAS)直接进样技术在石墨炉原子吸收光谱仪问世不久就已开始出现[1 ] ,并随着石墨炉技术的发展而不断改进和完善。目前测定原油中痕量金属元素一般都需要对原油进行预处理后再测定。常用的干灰化[2 ] 等预处理方法 ,操作繁琐且费时。石墨炉原子吸收光谱直接进样技术充分利用了石墨炉本身对样品基体具有灰化处理能力这一特点 ,原油可不经预处理 ,直接进样分析 ,这样就大大简化了操作步骤 ,缩短了分析时间。虽然直接测定原油中痕量金属元素有许多优点 ,但是在实际应用中尚有一定难度 ,这除了因其操作难度大、校正困难…     

涡流色谱技术在生物样品分析中的应用

生物样品的复杂性使其在进行分析测定前必须经过处理。传统的样品前处理方法(如液-液萃取、固相萃取等)耗时长且操作繁琐。涡流色谱作为在线萃取技术,可以实现生物样品直接进样,减少了样品处理步骤,有效富集纯化了分析物,是一种高通量、高选择性的生物样品前处理方法。为此,本文介绍了涡流色谱技术的原理及优势,并总结了不同涡流柱的特点及其在生物样品分析领域中的应用情况。     

区带流动分析技术测定水中的氨氮

建立区带流动分析技术快速测定水中氨氮的方法。实验条件:进样体积为200μL,进样流量为10μL/s,加热温度为130℃,检测时间为6 min,检测波长:660 nm,混合方法:样品与试剂在储存管中往复运动混合。氨氮质量浓度与吸光度在0～1.0 mg/L范围内呈良好的线性关系,相关系数r~2=0.998 7,方法检出限为0.01mg/L。测定结果的相对标准偏差为1.8%～3.5%(n=7),样品加标回收率为95.5%～104.3%。该方法检测速度快,精密度与准确度较高,仪器携带方便,为氨氮污染的现场快速监测提供了一种新的手段。     

有机微量燃烧分析中强挥发及不稳定液体样品的取样方法

在有机微量燃烧分析中,对于特殊性质的样品,如强挥发性或既吸水又挥发或在空气中不稳定的液体有机化合物,要获得正确的分析结果,除了必须掌握称量、分析方法本身技术外,还必须要有正确的取样和进样的方法,以防止样品在分析前的损失或破坏。在燃烧方法中,对于挥发性样品的装样称量,困难不大,其主要困难在于进样。一般文献上报导有二种方法:1.管外进样法,2.管内进样法。其要点是使样品防止挥发,损失。至于在空气中强烈吸潮而分解的样品,除了进样技术外,还必须在干燥或惰性气体下采样。     

电感耦合等离子体质谱(ICP-MS)法测定葡萄酒中的铜、镉、铅

建立了电感耦合等离子体质谱(ICP-MS)法直接测定葡萄酒中铜、镉、铅含量的一种快速、灵敏、准确的定量方法。采用微波消解及直接进样技术比对,结果表明,以钪(Sc)、铟(In)、铽(Tb)为内标元素,消除基体干扰及仪器漂移。在选定的仪器条件下,直接进样,外标法定量,相对标准偏差小于3%,加标回收率在86.4%~100%,精密度和准确度都能满足测定要求,成功用于能力验证样品的测定,结果令人满意。     

气相色谱-质谱测定环境样品的质量控制与质量保证

以环境样品分析为例,指出了气相色谱-质谱技术分析测定过程的质量控制的主要因素及措施,并从内标物、替代品、进样系统、色谱柱、质谱运行状态、保留时间、标准曲线、仪器软件系统等方面对如何提高分析过程的准确度进行了讨论。     

加速溶剂萃取-气相色谱-质谱法测定电子电气设备样品中多溴二苯醚

加速溶剂萃取(ASE)是近年发展起来的一种在较高的温度和压力条件下,采用有机溶剂萃取固体样品和半固体样品的前处理方法~([1～2]),该方法具有操作简单、使用方法、萃取速度快、有机溶剂用量少、回收率高、容易实现自动化等优点.本文建立了ASE-GC-MS测定电子电气设备样品中PBDEs的方法,优化了ASE萃取条件和GC-MS分析条件.     

快速原子吸收法测定蔬菜样品中微量铜

本文描述了蔬菜悬浮液直接进样非火焰原子吸收法测定微量钢的方法,讨论了样品的粉碎、匀浆及进样技术,研究了原子化温度程序等实验条件,并通过对各种蔬菜中微量铜测定的结果与常规法结果比较,确立了方法的可行性。     

Strong X-ray emission from electrified material

X-ray emission spectra are measured for electrified samples and the spectra are compared with those of electrically conductive samples. It is found that the electrified samples emit two orders of magnitude stronger X-rays than electrically conductive samples     

Thermal oxidation of isotactic polypropylene synthesized with a metallocene catalyst

The mechanism and kinetics of thermal oxidation of metallocene PP are investigated. It is shown that the rate of oxidation of the samples synthesized at a high temperature (40–70°C) is higher than that of the samples synthesized at a low temperature (20 and 30°C). The composition of oxidation products of PP samples; the kinetics of the accumulation of these products; and changes in structural, thermal, and thermophysical parameters during oxidation are analyzed in detail. Our data indicate that the oxidation of low-temperature samples and the oxidation of high-temperature samples obey different mechanisms. The oxidation of low-temperature samples corresponds to the radical-chain process, in which the intramolecular transfer of kinetic chains prevails. High-temperature samples are characterized by the intermolecular transfer of oxidation kinetic chains, which leads to the degradation of macromolecules. It is inferred that the rate and mechanism of thermal oxidation are determined by the microstructure of polymer chains.     

Systems of small metal particles: Optical properties and their structure dependences

Experiments on small particles usually require samples containing large numbers of particles. The properties of such samples are determined both by the properties of the individual particle and by collective effects, if particles are packed closely together. Collective optical effects strongly depend on the topography of the samples. It is shown that they can be classified according to the effective local electromagnetic field. Recent experiments and calculations are presented for optical extinction spectra in the spectral region of plasmon polariton excitations, which clearly show the different behaviour of effective medium-like samples and of samples containing particle aggregates.     

正交信号校正-插值-RBF法同时测定原料油中的铁、镍、钒

提出了一种解析分光光度同时测定数据的正交信号校正-插值-RBF(OSC-Interp-RBF)网络方法。该法将光谱阵用浓度阵正交,滤除光谱与浓度阵无关的信号,再用一维线性插值处理使训练集样本对待辩识空间形成较好的覆盖,使RBF网络能够更有效地提取信息,从而提高预测的准确性。将该算法用于模拟原料油中铁、镍、钒的测定数据解析及实际样的组分浓度预测的结果表明,对于合成样预测结果与组分实际浓度的相对误差,及对于实际样预测结果与按常规测定方法获得的结果的相对误差,绝对值均小于10%,结果令人满意。     

DSC Studies on Polytetrahydrofurans with Various Molecular Masses, Their Blends and Their Cured Samples

DSC studies are given for polytetrahydrofurans with molecular masses equal to 650, 1400, and 2900, for their blends, and for their cured samples. The samples were stored, annealed, and quenched to obtain the samples with different thermal histories. Two or more endothermic peaks appear in the DSC curves for the stored samples, even for the non-blended samples. A hyperbolic curve forced the plot of the highest melting temperature vs. the molecular mass to asymptote to about 50°C. The relationship between the highest melting temperature and the composition for the blended samples is suitable to linear or Fox’s relation. A peak and a shoulder appear in the DSC curves of the cured samples. As the samples are cooled at the faster rates in the thermal treatment, the shoulder appears at the lower temperatures. This revised version was published online in July 2006 with corrections to the Cover Date.     

气体组分的离子色谱分析检测技术

传统的离子色谱主要应用于水溶液中的阴、阳离子和极性化合物。随着离子色谱应用范围的扩大,通过合适的样品制备,将非水溶液的样品转化为水溶液,包括有机溶剂、固体样品和气态样品,特别是随着我们对大气环境、气体纯度以及呼出气体中气态样品的组成等方面的重视,越来越多的气体和气态样品,特别是离子态和极性化合物,可通过合适的样品制备、采集转化为水溶液,通过离子色谱技术进行分析。综述了气体组分的离子色谱检测技术,总结了气体样品、气溶胶以及液态样品中气体物质的制备和采集方法,运用离子色谱技术对上述样品进行测定,并对该技术运用过程中存在的问题及发展前景进行了展望。     

污水BOD5测定中外界条件的影响

对污水BOD5(五日生化需氧量)测定中各种外界条件的影响进行了初步探讨。通过大量实验数据说明了样品保存时间、培养温度和样品pH值对BOD5测定的具体影响。当样品保存时间大于24h时,检测结果的偏差将大于10%,不能正确反映水样中有机物的含量。培养温度对不同性质的水样的影响不同。对于可生化性好的水样,培养温度对其BOD5的影响很大,25℃和20℃之间的偏差可达40%;对可生化性不好的水样,培养温度对其BOD5的影响不大,一般为5%左右,在国标GB7488-87允许的准确度范围内,可忽略。水样的pH值对其BOD5的影响很大,当水样的酸碱度为中性时,测定的BOD5才能正确反映水样中有机物的含量;当水样呈酸性或碱性时测定的BOD5均小于正常值。     

Neutron activation analysis of bulk samples from Chinese ancient porcelain to provenance research

Neutron activation analysis (NAA) is an important technique to determine the provenance of ancient ceramics. The most common technique used for preparing ancient samples for NAA is to grind them into a powder and then encapsulate them before neutron irradiation. Unfortunately, ceramic materials are typically very hard making it a challenge to grind them into a powder. In this study we utilize bulk porcelain samples cut from ancient shards. The bulk samples are irradiated by neutrons alongside samples that have been conventionally ground into a powder. The NAA for both the bulk samples and powders are compared and shown to provide equivalent information regarding their chemical composition. Also, the multivariate statistical have been employed to the analysis data for check the consistency. The findings suggest that NAA results are less dependent on the state of the porcelain sample, and thus bulk samples cut from shards may be used to effectively determine their provenance.     

A new sampling format for the diagnostics of bovine infectious diseases in dried blood spots by ELISA

The detection of antibodies to bovine infectious diseases (enzootic bovine leucosis, viral diarrhea, and infectious rhinotracheitis) is performed by ELISA in dry whole blood samples obtained on porous membranes using a new sampling format. Several commercial test systems are used to diagnose the infections. The obtained data are compared to the results of the analysis of liquid samples of blood serum. The results of the analysis of dried and liquid samples are in full concordance. The new sampling format makes it possible to avoid using a cold chain for the transportation of samples to diagnostic laboratories and to simplify the storage of these samples.     

Melting behavior of polyethylene crystallized in a pressure capillary viscometer

The Melting of various polyethylene structures is compared by using data obtained on the Perkin-Elmer differential scanning calorimeter (DSC). Transparent, high-density samples crystallized under both orientation and pressure in the Instron capillary rheometer are compared with samples crystallized from dilute solution by stirring and with samples crystallized under high pressure. The latter two structures are assumed to contain extended-chain crystallites. By comparison, the melting points and the superheatability of the Instron samples are consistent with the presence of an extended-chain crystal component. The melting of irradiated samples crystallized in the rheometer is also observed to be consistent with this conclusion. In addition, DSC data are compared with the melting points defined with a polarized light microscope equipped with a hot stage.