ICP－AES中内标法的应用研究 Ⅲ．用内标法校正基体干扰

通过观测基体对分析元素发射强度的干扰情况，分析干扰机制，从而确定用来校正基体干扰的内标元素与分析元素的匹配条件。实验结果表明，只要选择合适的内标元素，可以校正基体干扰。     

ICP—AES中内标法的应用研究：Ⅲ.用内标法校正基体干扰

通过观测基体对分析元素发射强度的干扰情况，分析了扰机制，从而确定用来正基体干扰的内村元素与分析元素的匹配条件。实验结果表明，只要选择合适的内标元素，可以校正基体干扰。     

内标法在ICP－AES中的应用研究──Ⅰ．信号的相关性与精密度的改善

本文介绍了选择一系列具有不同物理性质的元素谱线来研究分析元素与内标元素间的内在联系。分别研究了背景之间、各谱线的信号与背景之间、分析信号与内标线信号之间的相关性。结果表明，只有当连续辐射背景较强时前两者才有较高的相关性。采用分析线信号与内标线的信号比可提高分析精密度，而内标元素的物理性质不必与分析元素的相匹配。同时详细分析了信号和背景波动的机制。     

端视等离子体原子发射光谱法中内标法校正的钠基体干扰

端视电感耦合等离子体原子发射光谱在分析过程中易电离元素引起的非光谱干扰，常常使分析结果产生偏差，就不同浓度Na基体对分析谱线产生的干扰进行了实验和研究，并用Y作为内标元素来补偿钠基体的干扰。得出在Robust条件，即高功率和低载气流速条件下，选择合适的离子线，并且离子线的总能量大于10eV下，用内标Y437.494nm可以很好的补偿不同Na含量的干扰。     

端视等离子体原子发射光谱法中内标法校正钠基体干扰

端视电感耦合等离子体原子发射光谱在分析过程中易电离元素引起的非光谱干扰 ,常常使分析结果产生偏差。就不同浓度Na基体对分析谱线产生的干扰进行了实验和研究 ,并用Y作为内标元素来补偿钠基体的干扰。得出在Robust条件 ,即高功率和低载气流速条件下 ,选择合适的离子线 ,并且离子线的总能量大于 10eV下 ,用内标Y 4 37.4 94nm可以很好的补偿不同Na含量的干扰。     

内标法在阳极溶出悬汞电极极谱法中的应用

某些痕量元素的测定常采用阳极溶出悬汞电极极谱法;但因方法包括了制备电极、电解富集、溶出曲线记录、蜂高测量等一系列操作,测得结果的精密度往往不高。我们在该法中引入了内标法,即在待测离子试液中选取含量固定的某一元素作内标,这一元素可以是试样中原来就有的,也可以在配制试液时新加入;作为内标元素以在测试条件下能得到与待测元素相互分开且峰高不过份悬殊的溶出曲线为适宜;测量结果以待测     

内标法在ICP—AES中的应用研究：Ⅰ.信息的相关性与精密度的改善

本文介绍了选择一系列具有不同物理性质的元素谱线来研究分析元素与内标元素间的内在联系。分别研究了背景之间，各谱线的信号与背景之间，分析信号与内标线信号之间的引关性，结果表明，只有当连续辐射背景较强时前者才较高的相关性，采用分析线信号怀内标线的信号比可提高分析精密度，而人标元素的物理性质不必与分析元素的相匹配，同时详细分析了信号和背景波动的机制。     

叠加内标法色谱定量分析

 叠加内标法是指在色谱定量分析中将内标法与叠加法结合的一种新的定量方法。叙述了叠加内标法定量的理论依据 ,规定了其操作步骤 ,并详细说明了这种方法的适用条件和优缺点。     

ICP发射光谱分析中浓度比法的应用——人工晶体分析

内标法是 ICP 发射光谱分析的方法之一。文献曾报道过向样品及标准溶液中加入等量的内标元素,通过测定分析物与内标的强度比值求含量,可以提高精密度与准确度。选择内标时,要考虑其光谱特性及雾化过程特性与分析物的特性相匹配。但有的研究结果表明,当一个元素的激发能和电离能与分析物有很大差别(甚至分别为原子线及离子线)时,只要适当选择操作条件,使谱线的信号间密切相关,仍可被选作内标。     

谈谈气-液色谱分析中的内标法

内标法是一种间接的或相对的校准方法。在分析测定样品中某组份含量时,加入一种内标物质以校准和消除由于操作条件的波动对分析结果的影响,从而提高分析结果的准确度。在气-液色谱定量分析中,内标法是一个重要技术,但不能认为是唯一的定量分析方法,其优点及分析准确度方面还不能作出十分明确的结论。     

Efficient synthesis of episulfones and of SO2 with any variation of oxygen isotopes using HOF.CH3CN

[reaction: see text] Episulfones are quite unstable and difficult to make compounds. HOF.CH(3)CN, a powerful oxygen transfer agent operating under very mild conditions, was successfully employed in converting episulfides to episulfones. Unlike other oxidizing agents, no episulfoxides were formed under standard conditions. Reacting H(18)OF.CH(3)CN with either an episulfide or an episulfoxide leads to the corresponding episulfone with all combinations of oxygen isotopes. Decomposition of such episulfones gives any desirable variation of S(18)O(x)()O (x = 16, 18).     

Precision at the low picogram level in the analysis of derivatized iodothyronine standards by capillary gas chromatography with electron-capture detection

Previously an acceptable precision (coefficient of variation less than 10%) could be obtained only part of the time for the peak areas of derivatized iodothyronine standards, even relative to that of a structurally close internal standard, 3,4-diiodo-3′,5′-dibromothyronine, when these compounds were analyzed at the low picogram level by capillary gas chromatography with electron-capture detection. This problem has now been ovecome, primarily by introducing a new design, material and conditioning of a direct vapor-injector insert. An extensive analysis under practical operating conditions of derivatized 3,5-di-, 3,5,3′-tri and 3,5,3′,5′-tetraiodothyronine at the 5-10-pg level, involving several changes in the injection equipment and several days of injections, now gives within-day coefficients of variation ranging from 2.7 to 7.7%, 1.5 to 5.3% and 1.8 to 5.2%, respectively, for the relative peak areas of these compounds.     

Theory of peak capacity in gradient elution

Peak capacity is the best measure of the performance of a gradient separation. In this paper, the theory of peak capacity for the standard operating conditions of reversed-phase and ion-exchange chromatography is outlined. The influence of the operating conditions on the peak capacity of a separation are discussed. Finally, bandspreading phenomena in gradient chromatography are analyzed.     

Comparison of the results for the analysis of individual chlorobiphenyl congeners in various interlaboratory exercises

A comparison is made between interlaboratory studies in which individual chlorobiphenyls (CBs) are measured in fish and sludge samples. The target coefficient of variation (CV(R)) between laboratories at CB levels of 0.01–1.0 mg/kg should be in the order of 20–30%. An improvement in the CV(R) is clearly shown in studies in which a learning program, paying attention to the optimization of gas Chromatographic operating conditions, is included. For standard solutions, where no interference problems of the matrix occur, excellent CV(R)s are obtained in the order of 6%. In fish oil CV(R)s of 10–30% and in sludge CV(R)s of 20–30% are reached.     

Strategies for determination of insulin with tandem electrospray mass spectrometry: implications for other analyte proteins?

Using human insulin (MW 5808 Da) as a model compound, the possible strategies towards optimization of sensitivity and selectivity of measurement by electrospray ionization with a standard triple quadrupole mass spectrometer were investigated. For measurement in selected ion-monitoring (SIM) mode, these strategies involved systematic variation of instrumental parameters and spray pH. In this investigation four different operating modes were used corresponding to positive/negative ionization modes with acidic/basic sprays and pH reversed (hereafter termed 'wrong-way-round' operation); the cone voltage was optimized for each mode of operation. When collision-activated dissociation (CAD) is employed, two additional operation modes are possible: namely, low collision energies (10-35 eV, CAD-l) for the generation of sequence-specific fragments and high collision energies (>80 eV, CAD-h) for the generation of nonspecific fragments. Overall, this results in twelve different modes of operation. Loop-injection of aqueous insulin standards were run for each of the twelve operating modes and measurements made for five different charge states (n = 2-6) observable with our instrument that has an upper mass limit of m/z 4000. The signal/noise (S/N) ratio was optimized for each charge state, resulting in 60 measurements. The best S/N ratios (20 000) were achieved under positive SIM conditions with charge state 6 (m/z 969) and under 'wrong-way-round' negative SIM conditions with charge state 3 (m/z 1935). Lower S/N ratios were observed under positive CAD-h conditions with charge state 5 (m/z 1163, S/N 15 000) and positive CAD-l conditions with charge state 6 (m/z 969, S/N 10 000). All other operating modes gave maximum S/N ratios of 4000. For measurement of insulin standards, the results obtained show SIM to give the best S/N ratio. However, for samples in complex matrices, our general experience suggests CAD to be the preferable operating mode. Consequently, for the development of a quantitative method for proteins in general, it might be advocated that all of the twelve operating modes and all relevant charge states be investigated to find the optimum S/N ratio.     

The influence of operating conditions on the evaluation of biological marker compound distributions in petroleum geochemistry by gas chromatorgaphy and gas chromatography/mass spectrometry

The effects of the operating conditions for gas chromatoraphy and gas chromatography/mass spectrometry (g.c./m.s.) on the observed distributions of biological marker compounds in petroleum are considered. Resolution and the accuracy and precision of quantification were investigated for components of geochemical significance. Methylsilicone stationary phases were generally suitable for aliphatic biomarker analysis, although some components co-eluted on these phases. The inclusion of ca. 5% phenyl groups into methylsilicone phases provided improved resolution of certain alkane biomarkers, and also allowed satisfactory analysis of classes of aromatic biomarker compounds. Vaporising and non-vaporising injection techniques in g.c./m.s. were compared for accuracy and reproducibility of relative component quantification. Cooled on-column injection wa found to be the most suitable technique in biomarker analysis. The effect of long-term variation in the operating conditions for the spectrometer on the reproducibility of quantification data was found to be at least as significant as the effect of the sample injection technique.     

气相色谱法测定汽油含氧化合物与苯

本着降低生产成本,开发仪器功能,提高工作效率,建立了双柱切换-反吹技术-气相色谱法(内标法)同时测定汽油中含氧化合物与苯。考察色谱阀的切换时间,柱温等因素对结果的影响,确定了最佳操作条件,同时对方法的精密度和重复性进行验证。结果表明,含氧化合物和苯的相对标准偏差为0.05%～0.2%,加标回收率分别为98.8%和96.7%,同时测定汽油中含氧化合物和苯方法的建立,其分析结果与石化标准方法分析结果一致。     

Improved accuracy for the analysis of soft magnetic alloys by inductively-coupled plasma atomic emission spectrometry by using advanced standardization procedures

The applicability of simultaneous ICP-OES for the accurate analysis of soft magnetic alloys has been investigated. Long-time signal variations of up to 40% can be observed under normal operating conditions. The scattering of the values can largely be compensated by a correction procedure with internal and external standardization where the intensity value of the analytical signal is first rationed to the simultaneously measured intensity of an internal standard line and after that recalibrated with an external standard. Not only the trueness but also the precision could be improved by using Cd as a real-time internal standard. This is attributed to a compensation for instrumental fluctuations as a result of the simultaneous measurement of both emission signals.