Determination of 206/207Pb isotope ratios by ICP-MS in particulate matter from the north sea environment

Summary The determination of lead isotope ratios can be used for source and pathway characterization of lead in the environment. The suitability of inductively coupled mass spectrometry (ICP-MS) was evaluated for the measurement of ^206/207Pb isotope ratios in several marine compartments as marine aerosols from different source regions and suspended particulate matter from the North Sea. Two different ICP-MS systems were used to carry out these investigations. First optimization studies have been performed to yield a sufficient precision (RSD <0.5%) in combination with a reasonable measuring time. This study has been carried out using the standard reference material NBS 981 with certified lead isotope ratios. Furthermore, it could be shown for marine environmental samples, that a precision of less than 0.5% RSD is attainable for counting rates of above approximately 50000 cps. As the following measurements of lead isotope ratios in marine aerosols from main source regions surrounding the North Sea demonstrated, this precision is sufficient to determine significant differences due to the origin of atmospheric lead. The analysis of aerosol samples revealed isotope ratios varying from as low as 1.10, which is close to that ratio for leaded gasoline in Europe to near background (modern lead) values of 1.20. The lead isotope ratios for the investigated suspended particulate matter ranges between 1.13 and 1.18. These values can be related to the solid discharge, the urban density and anthropogenic activity of the drainage basin.     

Validation of analytical methods used for determination of nitrate in soil

The standard method (ISO/DIS 14255) and the quick test were used for determination of nitrate in soil. We validated both methods using parameters such as accuracy, reproducibility within 1 day and between days, limit of detection and limit of quantification. The accuracy of the results was determined using the analysis of samples from the international interlaboratory scheme WEPAL. The accuracy of the standard method was good, while for the quick test the results were not accurate. The standard method showed a solid reproducibility of measurement results (in 1 day, relative standard deviation, RSD=0.2%; between days, RSD=0.8%). The quick test gave poorer results (in 1 day, RSD=6%; between days, RSD=7%). We tried to established the compatibility of both methods on real soil samples and we were satisfied to obtain the correlation coefficient 0.98 using the regression straight line. The analyses with the quick field instrument are much simpler and cheaper than the standard laboratory analyses and can be used for advising on nitrogen fertilisation.     

光电发射光谱法分析钛合金中的主要合金元素

依据光电发射光谱仪光源激发机理,结合钛合金的材料性能,选用火花放电激励光源和时间分解脉冲分布测光法,绘制钛合金中主要合金元素的工作曲线,对A l、V、Fe、S i、C、Mn、Cu、Mo、Sn、Zr、N i、Cr等元素进行光谱直接测定。测定结果与化学法测定结果基本一致,测定结果的相对标准偏差为0.72%~4.27%(n=11)。     

火焰原子吸收法测定山楂叶中钙、锰、铁、锌、镁、铜、铅、铬的含量

对广西山楂叶进行湿法消化处理,利用火焰原子吸收分光光度法测定了其中微量元素的含量。结果表明,山楂叶中含有较丰富的Ca、Mg、Fe、Mn。该法的加标回收率为99．6％～105．0％,RSD≤0．71％,测定结果准确。     

Concept of biogenic ferromanganese crust formation: coccoliths as bio-seeds in crusts from Central Atlantic Ocean (Senghor Seamount/Cape Verde)

At depths of 2,000 to 3,000 m, seamounts from the Cape Verde archipelago (Central Atlantic Ocean) are largely covered with ferromanganese crusts. Here we studied 60 to 150 mm thick crusts from the Senghor Seamount (depth: 2257.4 m). The crusts have a non lamellated texture and are covered with spherical nodules. The chemical composition shows a dominance of MnO2 (26.1%) and Fe2O3 (38.8%) with considerable amounts of Co (0.74%) and TiO2 (2.1%). Analysis by scanning electron probe microanalyzer (EPMA) revealed a well defined compositional zonation of micro-layers; the distribution pattern of Mn does not match that of Fe. Analysis by high resolution scanning electron microscopy (SEM) revealed that coccospheres/coccoliths exist in the crust material as microfossils; most of the coccospheres/coccoliths are not intact. The almost circular coccoliths belong to the type of heterococcoliths and are taxonomically related to species of the family Calcidiscaceae. By energy dispersive X-ray spectroscopic analysis an accumulation of the coccoliths in the Mn- and Fe rich micronodules was detected. Focused ion beam assisted SEM mapping highlighted that the coccoliths in the crust are Mn rich, suggesting that the calcareous material of the algal skeleton has been replaced by Mn-minerals. We conclude that a biologically induced mechanism has been involved in the formation of the crusts, collected from the Cape Verde archipelago from depths of 2,000 to 3,000 m in the mixing region between the oxygen-minimum surface zone and the oxygen-rich deep waters; the deposition process might have been triggered by chemical reactions during the dissolution of the Ca-carbonate skeletons of the coccoliths allowing Mn(II) to oxidize to Mn(IV) and in turn to deposit this element in the crust material.     

Spark discharge assisted laser induced breakdown spectroscopy

Laser induced breakdown spectroscopy is combined with a spark discharge to operate in a laser triggered spark discharge mode. This spark discharge laser induced breakdown spectroscopy (SD-LIBS) is evaluated for Al and Cu targets in air under atmospheric pressure. Significant enhancement in the measured line intensities and the signal-to-background ratios, which depend on the spark discharge voltage and the laser fluence, is observed in spark discharge laser induced breakdown spectroscopy when compared to laser induced breakdown spectroscopy alone for similar laser conditions. The measured line intensities increase with the applied voltage for both targets, and the ratio of the measured line intensity using spark discharge laser induced breakdown spectroscopy to that using laser induced breakdown spectroscopy is found to increase as the laser fluence is decreased. For Al II 358.56, such intensity enhancement ratio increases from 50 to 400 as the laser fluence is decreased from 48 to 4 J/cm² at an applied voltage of 3.5 kV. Thus, spark discharge laser induced breakdown spectroscopy allows for using laser pulses with relatively low energy to ablate the studied material, causing less ablation, and hence less damage to its surface. Moreover, applying spark discharge laser induced breakdown spectroscopy gives up to 6-fold enhancement in the S / B ratio, compared to those obtained with laser induced breakdown spectroscopy for the investigated spectral emission lines.     

Prediction of precision from signal and noise measurement in liquid chromatography: Mathematical relationship between integration domain and precision

Summary The precision of integration over noisy instrumental output for quantitative analysis is studied. A probability theory is developed to predict the relative standard deviation (RSD) of integration results over an integration domain from one-point integration (peak height measurement) to entire area integration in HPLC. Common integration modes of horizontal zero line and oblique zero line are taken into account, but no peak overlap is assumed. The question of the analytical superiority of peak height measurement or integration for quantitation is answered. In the HPLC apparatus used, the minimum RSD of measurements is found in the integration domain of ca. ±0.5 σ for analytes [peaks are approximated by the Gaussian signal of width, σ (standard deviation)]. The RSD of integration measurements is also shown to depend on the stochastic properties of background noise (uncorrelated noise and correlated 1/f type noise). The theoretical conclusion is verified by Monte Carlo simulation and HPLC experiments for some aromatic compounds. Second Part of series cited as Ref. [1].     

Simultaneous determination of sixteen major and minor elements in river sediments by energy-dispersive x-ray fluorescence spectrometry after fusion in lithium tetraborate glass

Fluvial sediments, including the NBS SRM-1645 Standard River Sediment, were fused in lithium tetraborate to form glass discs on which determinations of 16 elements (K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr and Pb) were obtained simultaneously at a single set of x-ray conditions by energy-dispersive x-ray fluorescence spectrometry (e.d.x.r.f.). Relatively high sample-to-flux ratios of 1:3 were employed to obtained determinations of several minor as well as major elements on a single disc. Lower sample concentrations 1:6 and 1:10 were also used with the NBS SRM-1645. Inter-element corrections for absorption by iron were significant for detectable elements heavier than iron. In the NBS SRM-1645 samples, corrections were made for the fluorescence of chromium by the Fe K lines as well as the absorption of the Fe K lines by chromium. A background correction was also necessary for manganese in NBS SRM-1645. At the lowest sample-to-flux ratio (1:10) good agreement was obtained between the e.d.x.r.f. determinations and the NBS values for all quantifiable elements except zinc. At higher sample-to-flux ratios, agreement with the NBS values was generally poorer with increasing sample concentration. The relative standard deviation (RSD) of the eight quantifiable major and minor elements (K, Ca, Ti, Mn, Fe, Zn, Sr and Zr) determined under a single set of x-ray conditions ranged from 2 to 9% (RSD) with a mean RSD of 4.4% for a set of replica discs fused with Lake Pueblo/Arkansas River sediment samples.     

Multi-element analysis of manganese nodules by atomic absorption spectrometry without chemical separation

Five manganese nodules, including the USGS reference nodules A-1 and P-1, were analyzed for Co, Cu, Fe, K, Mg, Mn, Na, Ni and Zn without prior chemical separation by using a simultaneous multi-element atomic absorption spectrometer with an air—cetylene flame. The nodules were prepared in three digestion matrices. One of these solutions was measured using sixteen different combinations of burner height and air/acetylene ratios. Results for A-1 and P-1 are compared to recommended values and results for all nodules are compared to those obtained with an inductively coupled plasma. The elements Co, Cu, Fe, K, Mg, Mn, Na, Ni, and Zn are simultaneously determined with a composite recovery for all elements of 100 ± 7%, independent of the digestion matrices, heights in the flame, or flame stoichiometries examined. Individual recoveries for Co, K, and Ni are considerably poorer in two digests than this composite figure, however. The optimum individual recoveries of 100 ± 5% and imprecisions of 1–4%, except for zinc, are obtained when Co, K, Mn, Na and Ni are determined simultaneously in a concentrated digest, and in another analytical sequence, when Cu, Fe, Mg, Mn and Zn are measured simultaneously after dilution. Determination of manganese is equally accurate in the two sequences; its measurement in both assures internal consistency between the two measurement sequences. This approach improves analytical efficiency over that for conventional atomic absorption methods, while minimizing loss of accuracy or precision for individual elements.     

原子吸收光谱法测定冬枣叶茶中的8种金属元素

采用湿法对沾化冬枣叶茶样进行消化处理,利用火焰原子吸收光谱法测定了茶中K、Na、Ca、Mg、Fe、Mn、Cu、Zn的含量.结果表明,该法的加标回收率为95.2%～104.2%,RSD≤3.35%.该法操作简单,结果准确,为开发和利用冬枣叶茶提供了一定的科学依据.     

Isotope ratios and abundance sensitivity obtained with an inductively coupled plasma-time-of-flight mass spectrometer

Isotope ratios and abundance sensitivities have been determined with an inductively coupled plasma-time-of-flight mass spectrometer (ICP-TOFMS). Abundance sensitivities are at least in the 10⁶ range for low abundance ions that precede high abundance ions. Three methods of detection for isotope-ratio measurement have been compared. The three systems involve gated detection followed by analog integration, analog averaging, or ion counting. Gated ion counting offers excellent precision—between 0. 64 and 1. 00% relative standard deviation (RSD). These values approach those predicted from counting statistics and are comparable to those reported for other inductively coupled plasma-mass spectrometry (ICP-MS) instruments. In addition, a greater number of accumulated counts or longer analysis times would afford precisions of 0. 1% with stable gating electronics. The accuracy of the counting method is in the 1–10% range if no correction for mass bias is performed. However, this ion counting method suffers from a limited dynamic range due to pulse pileup. Constant-fraction discrimination gated integration and commercial boxcar averager techniques offer a broader dynamic range because of their analog nature, but the attainable RSD values are limited by drift in the detection systems and by the methods employed to calculate an accurate ratio. Overall, mass bias in the ICP-TOFMS is more severe than previous work in ICP-MS due primarily to detection system bias.     

中草药龙胆中微量元素的形态分析

采用传统煎煮法对丽水当地中草药龙胆中钙、锌、铁、铜、锰、铅、镉和铬等8种元素进行提取,并用微孔滤膜分离提取液中可溶态与悬浮态;利用大孔吸附树脂分离可溶态中有机态与无机态;采用正辛醇/水分配体系模拟水煎液中这8种微量元素在人体胃肠中分配情况,再用火焰原子吸收光谱法(FAAS)测定了各种形态中的8种元素。研究结果显示:龙胆中8种元素的提取率在34.25%～74.53%,浸留比在49.58%～371.1%,悬浮态颗粒吸附率在6.5%～29.8%,该法对各元素的加标回收率在91.3%～108.5%;相对标准偏差小于3.5%;锌、铁、铜、锰在正辛醇/水分配体系中溶出性受酸碱性影响大些。     

镍钴锰酸锂中镍、钴、锰三元素摩尔比的能谱测定

采用扫描电子显微镜-X射线能谱(SEM-EDS)及电感耦合等离子体发射光谱(ICP-OES)法对锂离子电池用镍钴锰酸锂中镍、钴、锰三元素间的摩尔比进行了测定。结果显示,在SEM-EDS测定过程中,如果将样品压成片状,选择合理的测定电压,同时对镍、钴谱线的重叠峰进行分峰拟合,以独立正态分布峰的面积换算各元素的摩尔百分比,SEM-EDS的测定结果与ICP-OES的测定结果具有较高的一致性,二者相对偏差不大于5%。镍、钴、锰三元素摩尔比的SEM-EDS测量值的相对标准偏差(n=3)不大于1%。     

Lead isotopic compositions of environmental certified reference materials for an inter-laboratory comparison of lead isotope analysis.

Lead isotope ratios, viz. 207Pb/206Pb and 208Pb/206Pb, of the commercially available certified reference materials (CRMs) issued in Japan are presented with an objective to provide a data set, which will be useful for the quality assurance of analytical procedures, instrumental performance and method validation of the laboratories involved in environmental lead isotope ratio analysis. The analytical method used in the present study was inductively coupled plasma quadrupole mass spectrometry (ICPQMS) preceded by acid digestion and with/without chemical separation of lead from the matrix. The precision of the measurements in terms of the relative standard deviation (RSD) of triplicated analyses was 0.19% and 0.14%, for 207Pb/20Pb and 208Pb/206Pb, respectively. The trueness of lead isotope ratio measurements of the present study was tested with a few CRMs, which have been analyzed by other analytical methods and reported in various literature. The lead isotopic ratios of 18 environmental matrix CRMs (including 6 CRMs analyzed for our method validation) are presented and the distribution of their ratios is briefly discussed.     

Direct multielement trace analyses of silicon carbide powders by spark ablation simultaneous inductively coupled plasma optical emission spectrometry

A procedure for the direct analysis of silicon carbide powders (SiC) by simultaneous detection inductively coupled plasma optical emission spectrometry using a Spectro-CIROS™ spectrometer (CCD-ICP-OES) and a novel spark ablation system Spectro-SASSy (SA) as sample introduction technique is described. The sample preparation procedure for SA of non-conducting material is based on mixing the sample powders with a conducting matrix, in this case copper and briquetting pellets. Pressing time, pressure and mixing ratio are shown to be important parameters of the pelleting technique with respect to their mechanical stability for the reliability of the analysis results. A mixing ratio of 0.2 g +0.6 g for SiC and Cu, a pressure of 10 t cm^− 2 and a pressing time of 8 min have been found optimum. It has also been shown that the spark parameters selected are crucial for uniform volatilization. Electron probe micrographs of the burning spots and the analytical signal magnitude showed that a rather hard spark at 100 Hz was optimum. The determination of trace elements in silicon carbide powders is demonstrated using a calibration based on the addition of standard solutions. For Al, Ti, V, Mn and Fe detection limits in the lower µg g^− 1 range can be achieved. Internal standardization with Y in combination with the addition of standard solutions allows relative standard deviations in the range of 4 to 24% for concentration levels of the order of 3 to 350 µg g^− 1.     

火焰原子吸收法测定藿香中的微量元素

采用火焰原子吸收法测定了广藿香与土藿香中Ca、Mn、Fe、K、Cu、Mg、Zn七种微量元素的含量.方法的回收率在95.6%～110.0%之间,RSD在0.9%～2.5%之间,具有良好的准确度和精密度.结果表明,广藿香中Mn、Fe、K、Cu、Zn等五种元素的含量较为丰富,特别是Mn、K两种元素的含量远高于土藿香.此测定结果可作为探讨藿香中微量元素的含量与药效相关性的科学依据.     

Prediction of precision from signal and noise measurement in liquid chromatography: Mathematical relationship between integration domain and precision

Summary The precision of integration over noisy instrumental output for quantitative analysis is studied. A probability theory is developed to predict the relative standard deviation (RSD) of integration results over an integration domain from one-point integation (peak height measurement) to entire area integration in HPLC. Common integration modes of horizontal zero line and oblique zero line are taken into account, but no peak overlap is assumed. The question of the analytical superiority of peak height measurement or integration for quantitation is answered. In the HPLC apparatus used, the minimum RSD of measurements is found in the integration domain of ca. ±0.5 for analytes [peaks are approximated by the Gaussian signal of width, (standard deviation)]. The RSD of integration measurements is also shown to depend on the stochastic properties of back-ground noise (uncorrelated noise and correlated 1/f type noise). The theoretical conclusion is verified by Monte Carlo simulation and HPLC experiments for some aromatic compounds.Second Part of series cited as Ref. [1].     

山楂及其中药制剂中无机元素的光谱测定

采用灰化法对山楂、焦山楂、保和丸进行了处理,利用火焰原子吸收法测定了其中无机元素的含量,方法的回收率在95.7%～106.5%之间,相对标准偏差RSD在0.1%～2.6%之间,测定结果准确可靠.结果表明,山楂及其中药制剂中K、Ca、Mg、Fe含量较高.此测定结果可为探讨山楂中微量元素含量与药效的相关性提供科学数据.     

Evalution of sequential extractions on dry and wet sediments

A five-step sequential extraction procedure was applied on dried and wet Ballastplaat Scheldt estuary sediments. When wet (fresh) sediments were used, all sample handling up to the 3rd extraction step, inclusive, was carried out under inert atmosphere. The repeatability of the procedure was very good on dry samples. For Fe as for Mn, RSD values are lower than 4%, except for Mn in the fifth extraction step where a spread of 10% is observed. The observed RSDs for Pb are of the same order of magnitude as those for Mn. On wet samples the spread of the results is higher than on dried ones. The highest RSDs observed for Fe amount to 20%, for Mn to 15% but for Pb an RSD of up to 44% was found. Better homogenization of the solid sediment part of lyophilized sediments and different porosities of wet sediment sub-samples may be the explanation. These results also indicated that drying/oxidizing of the sediment sample causes a shift from less available/mobile metal fractions to more available/mobile fractions. The Mn and Fe oxyhydroxide spikes added to a wet sediment sample were recovered between 100±10%. The results obtained after changing the sequence of the extraction steps (multiple rotations and inversions were tested) corroborated the progressive increase in the aggressive nature of the extraction solutions in our standard scheme. Although there is also no need to change the ratio volume of extractant to amount of sediment, increasing the number of extraction repetitions in steps 1 to 3 resulted, for some of those extraction steps, in a partially modified analyte distribution. Finally the method was applied to sandy and muddy sediment cores of the Scheldt estuary and revealed clear differences between metal distributions in both types of sediment.     

Analysis of subcellular sized particles. Capillary electrophoresis with post-column laser-induced fluorescence detection versus flow cytometry

Flow cytometry (FCM) and more recently capillary electrophoresis with post-column laser-induced fluorescence detection (CE-LIF) have both been used for subcellular particle analysis but their analytical performance has not been compared. In this work, we compare a commercial FCM with an in-house built CE-LIF instrument using fluorescently labeled microspheres and isolated mitochondria. As evidenced by the relative standard deviation (RSD) of the individual fluorescence intensities, FCM is two-fold better than CE-LIF for microspheres with > or =1.5 x 10(6) molecules of equivalent soluble fluorescein (MESF). However, FCM has a comparatively low signal-to-noise ratio (S/N) and high RSD for microspheres with <1.5 x 10(6) MESF. CE-LIF, on the other hand, produces S/N ratios that are >25 times higher than FCM for all the microspheres tested and a lower RSD for microspheres with <1.5 x 10(6) MESF. When 10-N-nonyl acridine orange (NAO)-labeled mitochondria are analyzed, the S/N ratios of both techniques are similar. This appears to result from photobleaching of NAO-labeled mitochondria as they are detected by the LIF detector of the CE-LIF instrument. Both techniques have a niche in subcellular analysis; FCM has the advantage of collecting data for thousands of particles quickly, whereas CE-LIF consumes less than a nanoliter of sample and provides the electrophoretic mobility for individual particles.