气相色谱叠加定量方法的研究

叠加法是由内标法衍生而来的一种气相色谱定量方法。对于较复杂混合物的分析,当选择内标物困难时,用叠加法定量更为方便。本文在大量实验的基础上,提出了叠加法定量过程中应注意的一些问题。     

电感耦合等离子体原子发射光谱法(ICP-AES)测定铸造锌合金中高含量铝和铜

采用硝酸溶样,电感耦合等离子体原子发射光谱法(ICP-AES)测定铸造锌合金中高含量的铝和铜。分别用基体匹配法和内标法分析铸造锌合金中铝和铜含量的准确度、精密度和加标回收率,结果表明基体匹配法在测定铸造锌合金中铝的含量时相对误差小于0.4%,好于内标法,回收率稳定在104%~108%;内标法在测定铸造锌合金中铝和铜时的相对标准偏差在0.2%~0.5%,明显好于基体匹配法,其中内标Sc测定铜时的准确度、精密度和回收率均较高,内标Y测定Al的含量时效果也较好。     

电感耦合等离子体发射光谱法(ICP-AES)测定铸造锌合金中高含量铝和铜

采用硝酸溶样,电感耦合等离子体发射光谱法(ICP-AES)测定铸造锌合金中高含量的铝和铜。分别用基体匹配法和内标法分析铸造锌合金中铝和铜含量的准确度、精密度和回收率,结果表明基体匹配法在测定铸造锌合金中铝的含量时相对误差小于0.4%,好于内标法,回收率稳定在104%~108%;内标法在测定铸造锌合金中铝和铜时的相对标准偏差在0.2%~0.5%,明显好于基体匹配法,其中内标Sc测定铜时的准确度、精密度和回收率均较高,内标Y测定Al的含量时效果也较好。     

多种方法分析与评价乙酸乙酯合成实验中产物之纯度

采用气相色谱内标法、面积归一化法及NMR内标法3种方法对乙酸乙酯合成反应中的产物进行纯度分析.GC内标法可抵消由于操作条件的波动而带来的误差,只需内标物与待测组分在同样条件下出峰且分离度较好,定量精度高,测出的乙酸乙酯纯度最低;应用NMR内标法可同步完成纯度分析和结构鉴定,且无需引入校正因子,操作简便.     

偏二甲肼纯度分析方法的改进

采用毛细管气相色谱内标法代替标准工作曲线法测定偏二甲肼纯度(UDMH),内标法的使用避免了微量进样不准确的缺陷.结果显示,该方法线性范围宽,偏二甲肼的标准曲线相关系数为0.9959,样品加标回收率98.39%,样品的测定标准偏差为0.0015,方法的准确度高、重现性好.     

等离子体质谱法测定高纯氧化铥中痕量稀土杂质元素的研究

本文提出了ＩＣＰ－ＭＳ内标补偿校正法直接测定５Ｎ－６高纯氧化铥中１４种痕量稀土杂质的方法，研究了ＩＰＣ－ＭＳ测定的谱干扰和基体效应。     

二醇酯类内给电子体纯度的核磁共振氢谱内标法测定

建立了测定无对照品的新型二醇酯类内给电子体(6#酯、7#酯)纯度的核磁共振氢谱内标测定法。实验以氘代氯仿为溶剂,以苯甲酸甲酯标准物质为内标,设定合适的采样时间和延迟时间,选取适合的内标峰和样品定量峰,方法测定结果的相对标准偏差分别为0.31%和0.37%(n=6),且呈现良好的线性关系。样品经测量后的纯度平均值分别为98.6%和98.4%,与HPLC法测定结果符合。在没有标准对照品的情况下,核磁共振氢谱内标法可用于该二醇酯类内给电子体的纯度测定。     

新型薄层色谱内标法测定葛根素含量

以大豆甙元为内标物在高效硅胶薄层板上采用新型内标法测定了葛根素注射液、中药葛根及中成药玉泉丸中葛根素的含量,建立了新型TLC内标法测定葛根素的新方法。结果表明：用大豆甙元作为内标物测定葛根素可以满足TLC内标物的一般条件,新型TLC内标法测定葛根素的含量具有测定结果准确,精密度好,回收率高等优点。     

改进示波计时电位法

本文克服了dE/dt～E曲线线性范围窄、分辨率差等缺点,把dE/dt～E曲线的切口变成峰形,具有再现性好、线性范围宽、灵敏度高、分辨率好等优点.采用内标法和频谱分析进行了定量测试工作,取得了满意的结果.     

用电感耦合等离子体质谱法测定高纯稀土中稀土杂质时的基体影响

考察了基体对待测稀土杂质元素信号的影响，研究了内标对基体效应的补偿作用。对于不同的基体元素最佳的内标元素是不一致的，Ｇａ、Ｉｎ、Ｉ、Ｃｓ和Ｔｌ是稀土纯度分析中合适的内标元素。内标法简便易行，效果好，其测定方法的精度和回收率令人满意。     

内标法测定偏二甲肼中的杂质含量

偏二甲肼(Unsymmetrical D imethylhydrazine,UDMH)是液体火箭推进剂主体燃烧剂之一,它与硝基氧化剂等组成双组元液体推进剂作为火箭发动机的能量工质,被广泛应用于导弹、卫星及航天器的发射中。偏二甲肼中杂质含量水平对于保证火箭的顺利发射具有重要意义。在有关标准和技术规     

气相色谱法测定铸造用酚醛树脂粉中六次甲基四胺含量

以间-甲酚作为内标,建立毛细管气相色谱法测定铸造用酚醛树脂粉中六次甲基四胺的含量。色谱柱为DB–5石英毛细管柱(30 m×0.25 mm,0.25μm),采用FID检测器。用水溶解样品中的六次甲基四胺,经过滤分离后,在确定的色谱条件下进行测定。此方法测定结果的相对标准偏差为0.9%~2.1%(n=6),加标回收率在98.7%~100.2%之间,与HG/T 2755–1996方法测定结果比较,误差在±0.2%之内。该方法灵敏度和准确度均符合要求,方法可靠,可用于铸造用酚醛树脂粉中六次甲基四胺含量的测定。     

Analytical Strategy for the Determination of Selenium in Biological Materials by Inductively Coupled Plasma-Mass Spectrometry with a Dynamic Reaction Cell

Selenium was determined in serum, hair, and tobacco by inductively coupled plasma-mass spectrometry using ⁷⁷Se, ⁷⁸Se, and ⁸²Se. The set of standards method (SSM) and the standard addition method (SAM) were applied to calibration with and without the use of internal standards (⁷²Ge and ¹⁰³Rh). In addition, the usefulness of the dynamic reaction cell (DRC) with methane as the reaction gas was characterized. The results obtained in different conditions were evaluated in terms of precision and accuracy. It was demonstrated theoretically and experimentally that an internal standard is a potential source of systematic errors as it can be influenced multiplicatively and additively by its own interferents (independently of selenium). Furthermore, it was shown that—against common opinion—an internal standard can fail in elimination of chemical interference effects influencing selenium and in increasing of precision of selenium determinations. The DRC was shown to be effective in the elimination of additive effects, although the results obtained by both SSM and SAM with DRC were systematically positively erroneous. Finally, selenium was determined accurately in each examined sample when SAM was applied to calibration, and signals were measured either for ⁸²Se without the use of the DRC, or for ⁷⁷Se or ⁷⁸Se with the use of the DRC. In addition, it has also been shown that samples should be diluted prior to analysis to the greatest acceptable extent.     

汽油中苯的测定

采用高分辨毛细管气相色谱对汽油中的苯进行测定。在汽油样品组分中选定一组分为内标,测定样品后再用内加法添加苯,再次测定,并以两次测定的峰面积数据计算苯量。本文在汽油辛烷值的测定基础上,发展了一种新的汽油中苯量的测定方法：采用国产色谱仪,带内标的内加法即可对汽油中的苯量进行准确测定．在不同标号的汽油测定实验中,相对标准偏差不超过3％。与国标方法相比,该方法简便快速,对仪器设备要求低,提高了分析效率,降低了分析成本,便于推广。     

Evaluation of three calibration methods to compensate matrix effects in environmental analysis with LC-ESI-MS

In quantitative analysis of environmental samples using high-performance liquid chromatography–electrospray ionization mass spectrometry (HPLC-ESI-MS) one of the major problems is the suppression or, less frequently, the enhancement of the analyte signals in the presence of matrix components. Standard addition is the most suitable method for compensating matrix effects, but it is time-consuming and laborious. In this study we compare the potential of three calibration approaches to compensate matrix effects that occurred when seven analytes (naphthalene sulfonates) were quantified in time series samples of waters with different matrices (untreated and treated industrial wastewater). The data obtained by external calibration, internal calibration with one standard, and external sample calibration (corresponding to matrix-matched calibration) were compared with those obtained by standard addition. None of the three approaches were suitable for a sample series of highly loaded, untreated wastewater with highly variable matrix. For less heavily loaded and less variable samples (treated wastewater effluents), the external sample calibration provided reasonable results for most analytes with deviations mostly below 25% as compared to standard addition. External sample calibration can be suitable to compensate matrix effects from moderately loaded samples with more uniform matrices, but it is recommended to verify this for each sample series against the standard addition approach.     

On-Line Standard Addition Technique for the Determination of Elements in the Samples with High Dissolved Solids by ICP-OES: Application to Determination of Rare Earth Elements in Geological Samples

A simple and rapid on-line standard addition method for analysis of samples with high dissolved solids by ICP-OES is reported. The method involves on-line addition of standard solutions to the sample using a T-piece, prior to the sample introduction system. The standard addition method is commonly used in the analysis of samples with complex matrices. However, the conventional standard addition method is a tedious and time-consuming process. Therefore, in this study, on-line standard addition technique was offered to significantly decrease the analysis time and increase the simplicity of the standard addition method. The performance of the proposed method was tested by determination of rare earth elements in geological samples. This method showed a high level of accuracy in comparison with external calibration and internal standard addition methods.     

Fast Determination of Phenanthrene in Soil by Gas Chromatography-Mass Spectrometry Using Chemometric Resolution and Standard Addition Method

A method for fast determination of the component in complex samples by using gas chromatography‐mass spectrometry (GC‐MS) was developed and used for quantitative analysis of phenanthrene in soils. In the method, window independent component analysis (WICA) was used for resolving the mass spectrum and non‐negative immune algorithm (NNIA) was employed for obtaining the chromatographic profile. Therefore, spectral and chromatographic information of a specific component can be obtained from the measured GC‐MS data of overlapping and high background. Six soil samples collected from different places were analyzed. The tedious pretreatments in preparing the samples and the elution in the separation were simplified for speeding up the analysis. Due to the complexity of the matrix, standard addition method was adopted for the final quantification. The applicability of the method was validated with a spiked sample and the results of the six samples are reasonable.     

An LC-ESI-MS method for the quantitative analysis of bile acids composition in fecal materials

In this work, a liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI-MS) method was developed and validated for quantification of bile acids in fecal materials. Co-eluting matrix impurities in fecal materials have been shown to greatly suppress the ionization of analytes in mass spectrometry, which is known as the matrix effect. To correct large quantitative errors caused by the matrix effect, we developed a scheme that combined the standard addition method with internal standard (SA-IS). The fecal sample pretreatment involved a single step of extraction with ethanol. Bile acids were separated using a Luna C(18) column (150 mm, 2 mm i.d., 5 μm) with gradient elution. The deprotonated analytes were detected in selective ion monitoring mode. Our results showed that, by using this method, the accuracy of quantification was significantly improved in comparison to the conventional internal standard method. The linearity, sensitivity, accuracy and precision of the method were within the range of 0.05-5 μmol/L. This SA-IS method was successfully applied to the analysis of bile acids in the samples collected from patients diagnosed with inflammatory bowel disease.