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1.
《Analytical letters》2012,45(15):3333-3341
ABSTRACT A comparison was made of different digestion methods for the determination of iron and zinc in two types of bulgur wheat prior to their analysis in graphite furnace atomic absorption spectrometry. Samples were digested by means of acid treatment in room temperature, acid treatment at 60°C in a water bath and in a microwave oven and by dry ashing in open ah system. Except for microwave digestion, the samples proved to be unclear. The concentrations of the elements studied in the bulgur samples obtained by the four digestion methods are inconsistent in limits of standard deviations. It was found that aluminum sulfate (4μg/10μl sample) added to the samples acted as a modifier, improving the signal shape and increasing the stability of slurries obtained from digestion procedures. 相似文献
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Günter Knapp 《Mikrochimica acta》1991,104(1-6):445-455
High performance decomposition techniques for organic and inorganic samples are discussed. Wet decomposition in closed vessels with conventional and microwave heating enables the decomposition of a wide variety of sample materials. A complete mineralization of organic samples with nitric acid is just possible by means of the High Pressure Asher®. After microwave digestion 2–20% of the carbon of the introduced sample remains in the digestion solution. Trace elements in aqueous samples or in digestion solutions can be determined with high sensitivity and free of systematic errors by means of a combined analytical method consisting of a computer controlled preconcentration device (TraceCon®) and a simultaneous ICP emission spectrometer. 相似文献
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Three digestion procedures have been tested on lichen samples for application in the determination of major, minor and trace elements (Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, V and Zn) in lichen samples collected in Aegean Region of Turkey by inductively coupled plasma atomic emission spectrometer (ICP-AES). The acid mixture of concentrated HNO3, H2O2 and HF were used. The instrument was optimized using lichen matrix considering RF power, nebulizer pressure, auxiliary flow rate and pump rate. The accuracy of the overall analyses was first estimated by analysis of two certified reference materials. Good agreement between measured and reference values were found for almost all elements. As the second way of determining the accuracy, results obtained from independent analytical techniques (ICP-AES and instrumental neutron activation analysis (INAA)) were compared for all elements by analyzing real samples. Correlation coefficients of two techniques for the elements ranged between 0.70 (Mg) and 0.96 (Fe). Among the three digestion systems, namely microwave, open vessel and acid bomb, microwave digestion system gave the best recovery results. The method detection limit (MDL) was computed using reagent blanks of microwave digestion system since it provides cleaner sample preparation. Detection limit is adequate for all elements to determine the elements in lichen samples. The precision was assessed from the replicate analyses of reagent blanks of microwave digestion system and was found to be less than 1.5% relative standard deviation (R.S.D.). 相似文献
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Michael Krachler Hendrik EmonsCarlo Barbante Giulio CozziPaolo Cescon William Shotyk 《Analytica chimica acta》2002,458(2):387-396
Four analytical approaches, based on different physical principles, for the determination of antimony (Sb) and arsenic (As) in ancient peat samples were critically evaluated: (a) open vessel digestion/hydride generation-atomic absorption spectrometry (HG-AAS), (b) closed-pressurized digestion in a microwave oven followed by sector field-inductively coupled plasma-mass spectrometry (SF-ICP-MS), (c) digestion in a microwave autoclave and subsequent quadrupole-inductively coupled plasma-mass spectrometry (Q-ICP-MS) measurements and (d) instrumental neutron activation analysis (INAA). The quality control scheme applied, always included the use of adequate plant reference materials to ensure the accuracy and precision of the analytical procedures. Additionally, two internal peat reference materials were analyzed using all four analytical approaches, generally showing good agreement for both elements. Method detection limits for As and Sb provided by all procedures were approximately 5 and 2 ng g−1 which is sufficiently low for the reliable quantification of both elements in ancient, pre-anthropogenic peat samples. A comparison of As and Sb concentrations in a set of peat samples determined by INAA, HG-AAS and SF-ICP-MS revealed that INAA underestimated the values in a systematic manner, whereas HG-AAS and SF-ICP-MS data agreed very well. Best precision of the results was obtained by analytical procedures involving HG-AAS or Q-ICP-MS and varied from 3.6 to 4.3% and 7.1 to 7.5% for As (at about 0.5 μg g−1) and Sb (at about 0.1 μg g−1), respectively. The highest sample throughput (40 samples per run accomplished in 2 h) combined with low risk of sample contamination could be realized in the high-pressure microwave autoclave. The amount of sample required by all approaches was 200 mg, except for INAA which needed at least 25 times more sample mass to achieve comparable detection limits. For the quantification of As and Sb, inductively coupled plasma-mass spectrometry (ICP-MS) was preferred over INAA and HG-AAS, mainly because (a) less sample is needed and (b) As and Sb can be determined simultaneously. In addition, ICP-MS offers the possibility to measure concurrently a wide range of other elements which also are of environmental interest. 相似文献
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The efficiency of oxidation in wet decomposition procedures for organic materials can be of great importance to the quality of the analytical data from various measurement techniques. A novel, microwave-assisted, high-temperature/high-pressure UV-TiO2 digestion procedure was developed for the accelerated decomposition of various biological samples. The technique is based on a closed, pressurized, microwave digestion apparatus (MW). UV irradiation is generated by immersed electrodeless Cd discharge lamp operated by the focused microwave field in the single polymer vessel. To enhance oxidation efficiency, a photocatalyst TiO2 was added to the microwave heated Teflon bomb. Measures of digestion completeness were provided by the appearance of carbon content and determination of trace and minor elements, enabling a comparison of different digestion procedures and sample types. Compared with other digestion systems, unusually low residual carbon contents were obtained. For the organic compounds and biological samples digested, the residual carbon content was 1-2%, corresponding to a decomposition efficiency of 98-99%. The potential of the MW-UV-TiO2 system was illustrated by the decomposition of four certified reference materials (serum, urine, milk, arsenobetaine solution) and subsequent determination of trace and minor elements. Recoveries between 92% and 107% were found. 相似文献
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《Analytical letters》2012,45(5):1051-1063
Abstract The results obtained in the determination of mercury in solid wastes by AAS using two preparation methods1 are compared through statistical parametric and non-parametric tests, linear regression and informational analysis of variance. The informational analysis of variance (IANOVA) method is a distribution-free procedure valid under minimal assumptions. It is not influenced by the range of the data and has very satisfactory robustness properties. Applying this algorithm to compare the effectiveness of the traditional water-bath digestion method with the microwave digestion method discussed in ref. 1, it was possible to assess the proportional errors introduced by microwave digestion method concerning the analysis of mercury in waste samples. 相似文献
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《Analytical letters》2012,45(14):2415-2430
Abstract This paper demonstrates the use of a focused microwave method involving chemical digestion in two steps, mineralization and oxidation with H2O2, for the determination of Kjeldahl nitrogen in industrial wastewaters. The most influential variables of the process (viz., microwave power, mineralization time, and oxidation time) were optimized by using an experimental design in conjunction with acetanilide as the reference substance. Tests revealed microwave power to have little effect on the extent of digestion in the range studied. The optimum mineralization time and oxidation time were both in the region of 10 min. However, the latter two must be adjusted as a function of the concentration and ease of degradation of the Kjeldahl nitrogen present in each sample. The proposed method was applied to industrial wastewaters of variable origin and found to provide results on a par with those of the standard method for this purpose, with digestion times shorter than this by a factor ranging from 6 to 60 depending on the ease of degradation of the particular sample. 相似文献
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The occurrence of Pt in environmental matrices is increasing since the introduction of automobile catalytic converters. Given that Pt is bioavailable and causes biological effects in plants and animals, respective biomonitoring programs are in high demand. But the analytical methods for conducting such programs have not yet been sufficiently established. Therefore, a study was carried out to develop a microwave digestion of biological samples, which allows a rapid determination of Pt by adsorptive cathodic stripping voltammetry.A high pressure microwave system was used and the digestion was performed in HNO3 and HCl. After digestion the HNO3 was evaporated with a microwave assisted vacuum concentration set. The study resulted in a procedural detection limit of 37.5 ng L−1 and a relative standard deviation of 18%. A recovery study resulted in a Pt loss below 5%. The microwave assisted evaporation of HNO3 performed satisfactorily and up to 500 mL of the sample solution could be used for the voltammetric measurements without any effect on the peak heights. A direct comparison of Pt concentrations conducted after microwave digestion and digestion by high pressure ashing showed similar values. However, these promising results were not persistent throughout the repeated analysis using the same Teflon vessels. The vessels did not endure the harsh conditions and due to aging processes the Pt loss consistently increased until Pt determination in environmental relevant concentrations became impossible. Quartz vessels could not be employed as an alternative to the Teflon vessels, due to a lack of compatibility with the vacuum concentration system. Consequently, the results of this paper show that there is a need for further development of more resistant Teflon materials. 相似文献
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Understanding the transport of trace elements through a coal-fired power plant requires reliable analytical methods for these elements in all the ingoing and outgoing mass streams. Coal and different kinds of ashes comprise the most abundant mass streams in such a plant. As a continuation of our previous work, we have optimised a digestion method for the AAS determination of heavy metals in coal samples. It has become evident that complete dissolution of metals in coal samples and accurate results in subsequent analysis can be obtained by means of applying pressurised digestion under microwave heating. The combination of HNO3 (conc.) and HF (conc.) in the volume ratio of 50?:?1 attacked the sample well enough, and good recoveries for all the metals studied were obtained. Surprisingly good results were obtained also when HNO3 alone was used as the digestion acid. 相似文献
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Anna Leśniewicz Wiesław Żyrnicki 《International journal of environmental analytical chemistry》2013,93(2):147-158
Abstract Concentrations of 22 trace and nutritional elements in yew, pine and spruce needles collected from urban and industrial areas were determined by inductively coupled plasma atomic emission spectrometry. Dependence of concentrations of trace elements in conifers species on sampling site was investigated. Various procedures of sample digestion (different acids, conventional hot plate and microwave digestion methods, dry ashing) were examined and discussed. 相似文献
13.
Optimised method of coal digestion for trace metal determination by atomic absorption spectroscopy 总被引:1,自引:0,他引:1
Understanding the transport of trace elements through a coal-fired power plant requires reliable analytical methods for these
elements in all the ingoing and outgoing mass streams. Coal and different kinds of ashes comprise the most abundant mass streams
in such a plant. As a continuation of our previous work, we have optimised a digestion method for the AAS determination of
heavy metals in coal samples. It has become evident that complete dissolution of metals in coal samples and accurate results
in subsequent analysis can be obtained by means of applying pressurised digestion under microwave heating. The combination
of HNO3 (conc.) and HF (conc.) in the volume ratio of 50 : 1 attacked the sample well enough, and good recoveries for all the metals
studied were obtained. Surprisingly good results were obtained also when HNO3 alone was used as the digestion acid.
Received: 18 June 1998 / Revised: 23 September 1998 / Accepted: 24 September 1998 相似文献
14.
B. Danko H. Polkowska-Motrenko R. Dybczyński 《Journal of Radioanalytical and Nuclear Chemistry》2000,246(2):279-283
The influence of irradiation conditions on the results of Co determination in plant samples by radiochemical neutron activation analysis (RNAA), after the conventional and microwave assisted wet digestion, has been investigated. Nine CRMs of botanical origin were examined. The study has demonstrated that the effectiveness of mineralization depended significantly on the kind of sample and the irradiation conditions. When analyzed CRMs were subjected to long-term irradiation in a high neutron flux, the mineralization using the microwave technique was necessary to obtain the correct results of Co determination in some of the plant samples. It has been proved that microwave digestion in a mixture of HNO3+H2O2+HF should be a standard method of wet ashing, independent on matrix and irradiation conditions. 相似文献
15.
《Analytical letters》2012,45(5-6):526-538
The analytical conditions that enable the determination of traffic related platinum group elements (PGEs) in roadside grass using microwave digestion and electrothermal atomic absorption spectrometry were evaluated as an alternative to the biomonitoring of traffic related PGEs and Pb levels in urban areas. To optimize the analytical conditions and account for matrix effects that could import error in the analysis, method optimization was based on matrix simulation through analyte recovery from spiked unpolluted samples against a matrix blank. A mixture of nitric and hydrofluoric acid under progressively increasing microwave irradiation was optimized to afford the quantitative extraction of platinum group elements from plant matrix. Due to the low levels of platinum group elements in real samples, preconcentration was accomplished using sample evaporation followed by dissolution in dilute nitric acid prior to deliverance to the atomic detector. Quantitation limits below 1 ng g?1 for Pd and Rh and lower than 2 ng g?1 for Pt, were accomplished, enabling the monitoring of platinum group elements bioaccumulation in roadside grass with satisfactory recoveries, as determined from the analysis of spiked samples. The results from method application in an annual monitoring survey of PGEs and Pb levels in urban flora and other roadside media are presented and discussed. 相似文献
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《Analytical letters》2012,45(4):439-448
Abstract Laboratory robots are being used to perform sample preparation and routine analytical determinations 1,2. In addition to these routine applications, laboratory robots should be able to analyze the analytical procedure itself and select the optimal experimental condition for any analytical method. The application of the fixed-sized SIMPLEX algorithm, the Nelder and Mead variable sized SIMPLEX algorithm and response surface fitting methods in analytical robotics is presented 3. 相似文献
17.
电感耦合等离子体发射光谱法测定植物油中的磷 总被引:2,自引:0,他引:2
用电感耦合等离子体发射光谱法(ICP-AES)测定了植物油中的磷.采用多谱线拟合技术(MSF)校正了铜对P213.617 nm和P214.914 nm光谱干扰.比较了活性炭炭化灰化法和微波消解法两种样品前处理方法对分析结果的影响.结果表明这两种前处理方法所得结果都能与国标磷钼蓝分光光度法的分析结果吻合,其中活性炭炭化灰化法的方法检出限(0.053 mg/kg)较微波消解法的方法检出限(0.42 mg/kg)更低,所以对低含量的磷的检测结果其相对误差及精密度更好.该法应用于植物油中磷的测定. 相似文献
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P. Krause B. Erbslöh R. Niedergesäß R. Pepelnik A. Prange 《Fresenius' Journal of Analytical Chemistry》1995,353(1):3-11
The suitability of four different digestion procedures, i.e. i.) an aqua regia digestion according to DIN 38 414-S7, ii.) a pressure digestion using HNO3/HF in PTFE-vessels, iii.) a HNO3/HF + HCl-pressure digestion in PTFE-vessels and iv.) a HNO3/HF + HCl-pressure digestion using microwave induction, has been evaluated with regard to the quantitative determination of about 50 elements in environmental samples. Three sediments of the river Elbe and two standard reference materials (MESS-1 and NIST 1645) have been employed. The analytical results from the dissolved samples, obtained using inductively coupled plasma mass- and optical emission spectrometry as well as total reflection X-ray fluorescence spectrometry, have been compared with those obtained by instrumental neutron activation analysis. Only digestion procedures using HNO3/HF with a subsequent evaporation to dryness and dissolution in HCl have led to appropriate results for a wide range of elements (more than 50 elements in total). Because of its low contamination risk and its time saving, the microwave digestion is preferred. For this digestion procedure the accordance among the different instrumental methods used is high (better than 15% deviation) in general. A few elements (16) could be determined quantitatively only by a single method. 相似文献
19.
A novel approach to the study of microwave enhanced alkaline digestion was developed for rapid digestion of silicate samples. By using alkali metal hydroxide solution as microwave digestion solvent, the feasibility and principle of digestion were discussed for the determination of Fe2O3 contents in quartz, kaolin, feldspar and soda-lime-silica glass. The results obtained from four standard samples and six real world samples are in good agreement with the certified values, and are comparable to the predicted results from traditional alkaline digestion method. All the above demonstrates that this new proposed method is precise, accurate and can provide a simple, fast and energy saving procedure for the determination of components in silicate samples. 相似文献
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Determination of heavy metals in soil, mushroom and plant samples by atomic absorption spectrometry 总被引:3,自引:0,他引:3
The concentrations of heavy metals in the soil, mushroom and plant samples collected from Tokat, Turkey have been determined by flame and graphite furnace atomic absorption spectrometry after dry ashing, wet ashing and microwave digestion. The study of sample preparation procedures showed that the microwave digestion method was the best. Good accuracy was assured by the analysis of standard reference materials. The relative standard deviations for all measured metal concentrations were lower than 10%. In all cases, quantitative analytical recoveries ranging from 95 to 103% were obtained. Metal accumulation factors were calculated for mushroom and plant samples. High ratio of plants to soil cadmium, zinc and copper concentrations indicate that these elements are accumulated by mushrooms. Results obtained are in agreement with data reported in the literature. 相似文献