Controlled dissolution for elemental analysis of sample layers by inductively coupled plasma-mass spectrometry: a feasibility study

Aqueous acid mixtures at room temperature are used to partially dissolve steel samples. The dissolved elements are washed off the surface, diluted, and then determined by inductively coupled plasma-mass spectrometry (ICP-MS) using a magnetic sector mass analyzer. The amount of material removed is measured from the amount of Fe dissolved and increases linearly with HNO(3) concentration in the etch acid. Analyte concentrations in the solid are determined from the signal ratio of analyte ion/Fe(+). The shape of a plot of mass of element removed vs. nitric acid concentration yields information about the efficiency of the removal process and the likely chemical form of the element in the sample. For elements like Mn, Al, and W in steel, these plots have the same linear shape as that for the major element (Fe), and the measured concentrations agree well with the certified values. For problem elements like Nb and Ta, the plots have two linear regions with different slopes, and measured concentrations are lower than the certified values. Laser ablation ICP-MS and scanning electron microscopy (SEM) measurements show these elements to be associated together in the solid in refractory grains that are not dissolved to the same extent as the Fe matrix. For steel, the amount of Fe dissolved corresponds to an average depth of at least 4 microm, or 20 000 atomic layers.     

High-speed camera imaging for laser ablation process: for further reliable elemental analysis using inductively coupled plasma-mass spectrometry

Production of laser ablation-induced sample aerosols has been visualized using a high-speed camera device coupled with shadowgraphy technique. The time resolution of the method is 1 micros, and production of the sample grains was successfully defined by the imaging system. An argon-fluoride excimer laser operated at 193-nm wavelength was used to ablate the solid samples. When the laser was shot onto the sample (Si wafer), a dome-shaped dark area appeared at the ablation pit. This dark area reflects changes in refractive index of ambient He probably due to emission of electrons or ions from the ablation pit. The dark area expanded hemispherically from the ablation pit with a velocity close to the speed of sound (approximately 1000 m/s for He at 300 K). This was followed by the excitation or ionization of the vaporized sample, known as the plasma plume. Immediately after the formation of the plasma plume, sample aerosols were produced and released from the ablation pit along the propagation of the laser-induced shockwave. Production of the sample aerosols was significantly delayed (approximately 4 micros) from the onset of the laser shot. The typical speed of particles released from the ablation pit was 100-200 m/s, which was significantly slower than the reported velocity of the plasma plume expansion (104 m/s). Since the initial measured speed of the sample particles was rather close to the speed of sound, the sample aerosols could be rapidly decelerated to the terminal velocity by a gas drag force with ambient He. The release angle of the sample aerosols from the ablation pit was very shallow (<10 degrees ), which may be due to the downforce produced by the thermal expansion of the ambient gas above the ablation pit. The shallower release angle and the contribution of the downforce probably results in the redeposition of sample aerosols or vapor around the ablation pit. In fact, the degree of sample redeposition around the ablation pit can be effectively minimized by evacuation the sample cell down to 20 kPa. In the case of glass samples, almost no visible laser-induced sample particles could be found using the spatial resolution of our device. This was mainly due to the smaller size distribution of the sample aerosols from the glass materials. Differences in size distribution of the sample aerosols between Si wafers and glass materials can affect analytical sensitivity and precision of elemental analyses using the laser ablation-ICP-mass spectrometry (LA-ICPMS). Although details of the mechanism of production and release of the sample aerosols from the ablation pit are not fully understood, the present imaging device for laser ablation has various implications for further precise elemental and isotopic analyses using LA-ICPMS.     

Nanoelectrospray ion mobility spectrometry online with inductively coupled plasma-mass spectrometry for sizing large proteins, DNA, and nanoparticles

Recently it has been demonstrated that nanoelectrospray (nES) in conjunction with macro-ion mobility spectrometry (macroIMS) and condensed particle detection can be used to size various types of nanoparticles, including large biomolecules (proteins, DNA, etc.), having electrophoretic mobility diameters ranging from 3 nm to well over 100 nm. The technique is extremely sensitive; however, it lacks specificity as a result of the detector used. To explore the possibility to overcome this limitation, we demonstrate the direct coupling of the nES-macroIMS system to an inductively coupled plasma mass spectrometer (ICPMS). Technical challenges involving the coupling of the air-based nES-macroIMS with the argon-based ICPMS are addressed and overcome. The resulting novel hyphenated technique is used to determine the elemental composition of nanoparticles resulting from the electrospraying of solutions containing inorganic salts and acids (CsI and dimethylarsinic acid). Even though the sensitivity of the used ICPMS does not allow for the simultaneous sizing of proteins and the determination of their metal, metalloid, or halogen content, we have shown that it is feasible to detect and accurately size proteins at femtomole levels by adding CsI to their solutions and detecting the resulting Cs adducts. This is also possible with DNA molecules. A linear relationship between protein amount and ICPMS response for (133)Cs(+) is observed, thus hinting at the possibility of further developing the technique for quantitative analysis of large biomolecules.     

电感耦合等离子体质谱法测定铜精矿中碲的不确定度评定

采用乙醇增强电感耦合等离子体质谱法测定铜精矿中的碲,分析测量碲含量的不确定度来源,包括物质称量、标准溶液配制、标准曲线拟合、样品定容和样品重复性测定过程,并依据不确定的评定方法计算各不确定度分量以及合成不确定度。结果表明:铜精矿中碲的含量可表示为(3.953+0.324)μg/g。     

Gel electrophoresis coupled to inductively coupled plasma-mass spectrometry using species-specific isotope dilution for iodide and iodate determination in aerosols

In this paper, we present an online coupling of gel electrophoresis (GE) and inductively coupled plasma-mass spectrometry (ICP-MS) for the determination of iodine species (iodide and iodate) in liquid (seawater) and aerosol samples. For the first time, this approach is applied to the analysis of small molecules, and initial systematic investigations revealed that the migration behavior as well as the detection sensitivity strongly depends on the matrix (e.g., high concentrations of chloride). These effects could consequently affect the accuracy of analytical results, so that they need to be considered for the analysis of real samples. The technique used for quantification is species-specific isotope dilution analysis (ssIDA), which is a matrix-independent calibration method under certain conditions. We demonstrate that the use of 129I-enriched iodide and iodate allows the correction of the impact of the matrix on both, the electrophoretic migration and the detection sensitivity of the ICP-MS. After optimization, this coupling offers a novel and alternative method in the analysis of iodine compounds in various matrices. Here, we demonstrate the analytical capability of the technique for the chemical characterization of marine aerosols. The results show the presence of iodide and iodate at the ng m(-3) and sub-ng m(-3) level in the investigated aerosol samples, which were taken at the coastal research station in Mace Head, Ireland. These results are in good agreement with other recent studies, which demonstrated that the iodine chemistry in the marine atmosphere is only poorly understood. In addition to iodide and iodate, another iodine compound could be separated and detected in certain samples with high total iodine concentrations and was identified as elemental iodine, probably in form of triiodide, by peak matching. However, it may arise from an artifact during sample preparation.     

Use of the inductively coupled plasma mass spectrometry for element analysis of environmental objects

Capabilities and limits of the inductively coupled plasma mass spectrometry (ICP-MS) are discussed by the examples of element analysis of natural and drinking water, soils, ground, bottom sediments, phytogenous samples, and aerosols. It is shown that this method in combination with simpler atomic-emission technique allows for widening the range of detected elements, simplify the mass-spectrometry analysis, and improve its reliability. Examples and metrological characteristics of techniques for studying various environmental objects are discussed.     

Pore exclusion chromatography-inductively coupled plasma-mass spectrometry for monitoring elements in bacteria: a study on microbial removal of uranium from aqueous solution

The interstitial spaces between spherical particles in a packed column can act as a sieve that passes microorganisms below a certain size. If the bed is a perfusion-type material (containing a binary distribution of large and small pores), colloidal-size microorganisms are subject only to pore exclusion, while all molecules are subject to size exclusion among the various pores. Thus, microorganisms elute first, followed by macromolecules, and then small molecules. Coupling this separation method to an ICP magnetic sector mass spectrometer provides a sensitive, direct means to study the microbial uptake of heavy metals (i.e., uranium) from their surrounding environments. Multiple metal ions can be monitored in the microorganism and in the surrounding solution. In this way, definitive information can be provided for the remediation of radioactive waste sites. The effect of uranium on microbial growth is also discussed.     

Quality, safety and sustainability in food distribution: a review of quantitative operations management approaches and challenges

The management of food distribution networks is receiving more and more attention, both in practice and in the scientific literature. In this paper, we review quantitative operations management approaches to food distribution management, and relate this to challenges faced by the industry. Here, our main focus is on three aspects: food quality, food safety, and sustainability. We discuss the literature on three decision levels: strategic network design, tactical network planning, and operational transportation planning. For each of these, we survey the research contributions, discuss the state of the art, and identify challenges for future research.     

Inductively coupled plasma mass spectrometry with on-line leaching: a method to assess the mobility and fractionation of elements

A new technique has been developed to assess the mobility and site of specific elements in complex natural materials such as rocks. Concentration profiles during leaching were obtained by pumping reagents (water, 1% HNO3, 10% HNO3, 30% HNO3), either continuously or with flow injection, through a microcolumn of sample while continuously monitoring analyte signals by inductively coupled plasma mass spectrometry (ICPMS). Compared to batch extraction procedures normally used, the approach involves minimal sample preparation and reduced contamination since the leaching is performed in a closed system. Continuous on-line monitoring also allows a greater resolution of the various phases reacting with given reagent. Compared to continuous leaching, flow injection increased the resolution of the various phases using discrete injections of reagents while reducing reagent consumption and minimizing etching of the MS interface. Furthermore, sensitivity was preserved by injecting into air instead of an aqueous carrier. Whether in the continuous or flow injection modes, the proposed approach provides real-time data on what phases are breaking down and what metals are released. It can therefore be used to design effective leaching strategies and to trace isotopic compositions. However, the resulting spectra are complex and the correct determination of some elements requires high-resolution ICPMS.     

Lab-on-a-chip technologies for massive parallel data generation in the life sciences: A review

Lab-on-a-chip (LOC) technology is an important and rapidly developing research field focused on improving experimentation and analysis in the life sciences through miniaturization of full analytical systems into (monolithic) chip substrates. Since its emergence in the 1970s [1], the field has matured, gaining tremendous momentum in the last two decades. Miniaturization and integration of analytical processes on a chip can offer enormous advantages over existing technologies and can create a range of novel opportunities in the life sciences. The developments in the field have led to significant increases in analysis throughput, more than billion-fold sample volume reductions and increased separation efficiency. Despite its potential for the life sciences, the existence and the implications of LOCs are not widely known outside its community.The aim of this review is to introduce scientists from different disciplines to LOC technology. We will discuss the most important LOCs, their physical operating principles and the unique benefits that can be gained through miniaturization. We will conclude this review with a discussion of the potential of LOCs for massive parallel data generation and their potential implications for the life sciences.     

Multivariate pattern matching of trace elements in solids by laser ablation inductively coupled plasma-mass spectrometry: source attribution and preliminary diagnosis of fractionation

Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) is used with two variations of principal components analysis (PCA) for objective, routine comparisons of forensic materials without time-consuming and destructive sample dissolution. The relative concentrations of trace elements in a solid sample are examined to provide a "fingerprint" composition that can be used for identification and source matching of the material. Residue samples are matched to bulk materials using PCA. Variation of laser focus and PCA are also used to diagnose the severity of elemental fractionation in two metal samples that are prone to fractionation, brass and steel. Such fractionation remains the most significant limitation for accurate quantitative analyses by LA-ICPMS.     

Separation,preconcentration and inductively coupled plasma-mass spectrometric (ICP-MS) determination of thorium(IV), titanium(IV), iron(III), lead(II) and chromium(III) on 2-nitroso-1-naphthol impregnated MCI GEL CHP20P resin

A simple and effective method is presented for the separation and preconcentration of Th(IV), Ti(IV), Fe(III), Pb(II) and Cr(III) by solid phase extraction on 2-nitroso-1-naphthol impregnated MCI GEL CHP20P resin prior to their inductively coupled plasma-mass spectrometric determinations. The influence of analytical parameters including pH of the aqueous solution, flow rates of sample and eluent solutions and sample volume on the quantitative recoveries of analyte ions was investigated. Matrix effects caused by the presence of alkali, earth alkali and some metal ions in the analyzed solutions were investigated. The presented solid phase extraction method was applied to BCR-144R Sewage Sludge (domestic origin), BCR-141R Calcareous Loam Soil, NIST 1568a Rice Flour and NIST 1577b Bovine Liver certified reference materials (CRMs) for the determination of analyte ions and the results were in good agreement with the certified values. The separation procedure presented was also applied to the various natural water samples collected from Turkey with satisfactory results.     

International publication patterns in social sciences: A quantitative analysis of theIBSS file

A scientometric analysis of social science literature is tried by using the machine-readable files of theIBSS 1981–1985. This is a comprehensive international bibliography in social sciences including cultural anthropology, economics, political science and sociology. Data used were 40,313 monograph records in theIBSS files. First, the number of scholarly monographs was examined by country. As a result, it is shown that a large number of monographs was published by only a very small number of countries. Second, the number of monographs was examined by language. A similar pattern as that of countries was observed. Third, the relationship between the publishing country and the language used is discussed. It is clarified that some languages, such as English, French and Spanish, are used in many countries because of their historical background such as colonization. Finally, we examined the correlation among the number of published monographs, GDP, population and the number of people attaining a university education. A regression model that incorporates GDP as explanatory variables explains well the variation of the number of monographs by countries (R²=0.77).     

A method for the quantitative analysis of iron speciation in meat by using a combination of spectrophotometric methods and high-performance liquid chromatography coupled to sector field inductively coupled plasma mass spectrometry

The determination of the heme and non-heme iron fractions in raw and cooked beef steak by using spectrophotometric methods and high-performance liquid chromatography coupled to a double-focusing sector field inductively coupled plasma mass spectrometer (HPLC-SF-ICPMS) is reported. Size exclusion chromatography coupled to SF-ICPMS was used to measure the iron-containing biomolecules in the samples. This approach allowed for the direct on-line detection of the most abundant iron isotope 56Fe without interference from 40Ar16O. The HPLC-ICPMS results for the iron speciation analysis of a raw beef steak, used as an analytical quality control (AQC) sample, showed that the main iron biomolecule present was the heme iron-containing protein myoglobin. For the AQC sample, the agreement among the HPLC-ICPMS method, the non-heme iron spectrophotometric method, and the total iron concentration showed 100% recovery of iron. The sum of the different iron-containing compounds determined using the developed HPLC-ICPMS method accounted for all the iron-containing compounds extracted. The analysis of myoglobin in steak by HPLC-ICPMS showed that on cooking the concentration was reduced by 85%. However, a spectrophotometric method specific for heme iron showed that it was still intact, even after heating to 80 degrees C. The measurement of the total iron in the cooked steak and the HPLC extracts by inductively coupled plasma optical emission spectroscopy (ICP-OES) indicated that the extraction method for the HPLC analysis was no longer applicable and that loss of the heme group from the protein rendered it incompatible with the size exclusion separation. The detection limit (concentration equivalent to 3 times the baseline for a blank injection) of the HPLC-ICPMS method was 2.4 ng as iron. The results demonstrate that a combination of analytical methods can be used to provide valuable information about dietary levels of nutritionally important metal-containing compounds as well as the efficiency of established extraction methods for raw and cooked meat samples.     

Inductively coupled plasma atomic emission spectrometry: an efficient tool for precise determination of Mg/Ca and Sr/Ca ratios in biocarbonates

A method is developed to precisely determine Mg/Ca and Sr/Ca ratios in biocarbonates by inductively coupled plasma atomic emission spectrometry (ICP-AES). This method precision (RSD%) is 0.52% for Mg/Ca and 0.28% for Sr/Ca, respectively. The precision suggests that ICP-AES is satisfactory for supplying good quality Mg/Ca and Sr/Ca data of biocarbonates for paleo-reconstruction. This ICP-AES technique was applied to 51 continuous coral subsamples, and the results show annually periodical variations in coral Mg/Ca and Sr/Ca ratios, which are consistent with previous findings.     

Role of interdisciplinarity in computer sciences: quantification,impact and life trajectory

The tremendous advances in computer science in the last few decades have provided the platform to address and solve complex problems using interdisciplinary research. In this paper, we investigate how the extent of interdisciplinarity in computer science domain (which is further divided into 24 research fields) has changed over the last 50 years. To this end, we collect a massive bibliographic dataset with rich metadata information. We start with quantifying interdisciplinarity of a field in terms of the diversity of topics and citations. We then analyze the effect of interdisciplinary research on the scientific impact of individual fields and observe that highly disciplinary and highly interdisciplinary papers in general have a low scientific impact; remarkably those that are able to strike a balance between the two extremes eventually land up having the highest impact. Further, we study the reciprocity among fields through citation interactions and notice that links from one field to related and citation-intensive fields (fields producing large number of citations) are reciprocated heavily. A systematic analysis of the citation interactions reveals the life trajectory of a research field, which generally undergoes three phases—a growing phase, a matured phase and an interdisciplinary phase. The combination of metrics and empirical observations presented here provides general benchmarks for future studies of interdisciplinary research activities in other domains of science.     

Development of an on-line flow injection Sr/matrix separation method for accurate, high-throughput determination of Sr isotope ratios by multiple collector-inductively coupled plasma-mass spectrometry

This work introduces a newly developed on-line flow injection (FI) Sr/Rb separation method as an alternative to the common, manual Sr/matrix batch separation procedure, since total analysis time is often limited by sample preparation despite the fast rate of data acquisition possible by inductively coupled plasma-mass spectrometers (ICPMS). Separation columns containing approximately 100 muL of Sr-specific resin were used for on-line FI Sr/matrix separation with subsequent determination of (87)Sr/(86)Sr isotope ratios by multiple collector ICPMS. The occurrence of memory effects exhibited by the Sr-specific resin, a major restriction to the repetitive use of this costly material, could successfully be overcome. The method was fully validated by means of certified reference materials. A set of two biological and six geological Sr- and Rb-bearing samples was successfully characterized for its (87)Sr/(86)Sr isotope ratios with precisions of 0.01-0.04% 2 RSD (n = 5-10). Based on our measurements we suggest (87)Sr/(86)Sr isotope ratios of 0.713 15 +/- 0.000 16 (2 SD) and 0.709 31 +/- 0.000 06 (2 SD) for the NIST SRM 1400 bone ash and the NIST SRM 1486 bone meal, respectively. Measured (87)Sr/(86)Sr isotope ratios for five basalt samples are in excellent agreement with published data with deviations from the published value ranging from 0 to 0.03%. A mica sample with a Rb/Sr ratio of approximately 1 was successfully characterized for its (87)Sr/(86)Sr isotope signature to be 0.718 24 +/- 0.000 29 (2 SD) by the proposed method. Synthetic samples with Rb/Sr ratios of up to 10/1 could successfully be measured without significant interferences on mass 87, which would otherwise bias the accuracy and uncertainty of the obtained data.     

Potential of far-ultraviolet absorption spectroscopy as a highly sensitive quantitative and qualitative analysis method for aqueous solutions, part I: determination of hydrogen chloride in aqueous solutions

This paper reports the usefulness of far-ultraviolet (FUV) absorption spectroscopy in highly sensitive quantitative and qualitative analysis of aqueous solutions. We propose a totally new idea for the utilization of FUV spectroscopy in pure water and aqueous solution analyses. We use an absorption band near 170 nm due to an n --> sigma* transition of water. The intensity of the foot of this band, which can be observed in the 190-210 nm region by use of an ordinary ultraviolet-visible (UV-Vis) spectrometer, is very sensitive to changes in hydration and hydrogen bonds of water. To demonstrate the potential of FUV spectroscopy in analytical chemistry, we undertook three kinds of experiments. The first one is concerned with the discrimination of eight kinds of commercial natural mineral water. The eight kinds of mineral water can be discriminated straightforwardly from the spectral patterns in the 190-250 nm region without any spectral pretreatment or spectral analysis such as multivariate analysis. The second experiment is the determination of hydrogen chloride (HCl) in aqueous solutions. FUV spectra of aqueous solutions of HCl over a concentration of 0-20 ppm were measured. A calibration model for predicting the concentration of HCl in the aqueous solutions was developed based on the absorbance at 193 nm. This method does not require any spectral pretreatment or multivariate analysis. The correlation coefficient and standard error of prediction of the calibration model developed are 0.9987 and 0.18 ppm, respectively. The detection limit of the proposal method for the determination of HCl in aqueous solutions was estimated to be 0.5 ppm (13.7 microM). The determination of HCl was also tried for natural mineral water to which HCl solutions with the concentrations of 2, 4, 6, 8, 12, 16, and 20 ppm were artificially added. The third study was the determination of ammonia (NH3) and hydrogen peroxide (H2O2) in aqueous solutions containing both NH3 and H2O2. It has been found that the present method is also useful for the determination of the two-component system.