共查询到10条相似文献,搜索用时 156 毫秒
1.
D. Weiss W. Shotyk H. Schäfer U. Loyall E. Grollimund M. Gloor 《Analytical and bioanalytical chemistry》1999,363(3):300-305
Different acid compositions (HNO3, H2O2, HF and HClO4) and low pressure microwave digestion were applied to the microwave assisted dissolution of ancient peats. The digests were
evaluated with respect to the decomposition of the inorganic and organic fraction of peats and to an optimised determination
of Pb by differential pulse anodic stripping voltammetry (DPASV). Addition of hydrofluoric acid was necessary to achieve a
complete dissolution of the resistant inorganic phase of the peat and to obtain the total Pb concentration. Addition of perchloric
acid decreased the concentration of dissolved organic carbon significantly, enabling reliable voltammetric signals for Pb
determinations with satisfying peak shape, baseline, sensitivity, and precision. The limit of detection for Pb in peats was
1 ng/mL in the acid digest, equivalent to 0.2 μg/g in solid peat. This allowed the determination of low, pre-industrial concentrations
of Pb in peat bogs from various locations (Europe and SE Asia). A chelation column used to isolate the metals from the complex
matrix to further improve the detection limits failed to provide good recoveries for the peats and plants.
Received: 12 June 1998 / Revised: 24 July 1998 / Accepted: 28 July 1998 相似文献
2.
This paper summarizes several key points in applying the microwave preparation technique to the elemental analysis of aquatic
sediments and reports systematic experiments in searching for an optimal microwave preparation procedure for element analysis
in sediment samples. The determination of the elements Cu, Pb and Cd in a standard reference aquatic sediment sample (CRM
280, COMEUR) was achieved by first digesting the samples in a microwave oven equipped with PFA advanced composite vessels,
followed by AAS measurement. The influence of microwave power, digestion time, various dissolution reagents and the HF removing
conditions was studied. It has been shown that for a 0.1 g sediment sample the optimal microwave preparation conditions are:
4–5ml HNO3/HF/H2O2 as solvent, digesting time 30 min with 100% microwave power and evaporating the residual acid within 8 min in an open vessel
at 80 °C. The element recovery rates with AAS measurement can reach up to 92.4–100.6%.
Received: 23 July 1996/Revised: 23 September 1996/Accepted: 25 September 1996 相似文献
3.
Optimization of microwave‐assisted extraction for six inorganic and organic arsenic species in chicken tissues using response surface methodology 下载免费PDF全文
Response surface methodology was applied to optimize the parameters for microwave‐assisted extraction of six major inorganic and organic arsenic species (As(III), As(V), dimethyl arsenic acid, monomethyl arsenic acid, p‐arsanilic acid, and roxarsone) from chicken tissues, followed by detection using a high‐performance liquid chromatography with inductively coupled mass spectrometry detection method, which allows the simultaneous analysis of both inorganic and organic arsenic species in the extract in a single run. Effects of extraction medium, solution pH, liquid‐to‐solid ratio, and the temperature and time of microwave‐assisted extraction on the extraction of the targeted arsenic species were studied. The optimum microwave‐assisted extraction conditions were: 100 mg of chicken tissue, extracted by 5 mL of 22% v/v methanol, 90 mmol/L (NH4)2HPO4, and 0.07% v/v trifluoroacetic acid (with pH adjusted to 10.0 by ammonium hydroxide solution), ramping for 10 min to 71°C, and holding for 11 min. The method has good extraction performance for total arsenic in the spiked and nonspiked chicken tissues (104.0 ± 13.8% and 91.6 ± 7.8%, respectively), except for the ones with arsenic contents close to the quantitation limits. Limits of quantitation (S/N = 10) for As(III), As(V), dimethyl arsenic acid, monomethyl arsenic acid, p‐arsanilic acid, and roxarsone in chicken tissues using this method were 0.012, 0.058, 0.039, 0.061, 0.102, and 0.240 mg/kg (dry weight), respectively. 相似文献
4.
Henryk Matusiewicz 《Mikrochimica acta》1993,111(1-3):71-82
A commercial laboratory microwave acid digestion system was evaluated for the acid dissolution of ceramic powders (Al2O3, AlN, BN and Si3N4) prior to the determination of their trace element content by microwave induced plasma atomic emission spectrometry. Newly designed vessels, capable of withstanding internal pressures of over 110 bar, provide rapid and satisfactory results for sample dissolution. Sample preparation time was approximately 30 min (including the subsequent cooling time and preparation of the final solution). Results from conventional stainless-steel acid digestion vessel (Teflon bomb) dissolution are compared with the microwave bomb results of microwave plasma atomic emission spectrometry. 相似文献
5.
Alla Dolgopolova Dominik J. Weiss Reimar Seltmann Chris Stanley Barry Coles Andriy K. Cheburkin 《International journal of environmental analytical chemistry》2013,93(12):889-899
A reliable and robust procedure using closed-vessel microwave digestion of lichens and leaves for precise and accurate determination of trace elements (Pb, Zn and Cu) and stable Pb isotope ratios is presented. The method was developed using certified reference material CRM 482 Pseudovernia furfurea (Lichens), NIST 1515 (Apple Leaves) and NIST 1547 (Peach Leaves) and tested on lichens from a mining site in Russia. A mixture of 3?mL of HNO3, 3?mL of H2O2, 2?mL of H2O and 0.8?mL of HF ensured complete sample dissolution with 100?±?5% recovery for Pb, Zn and Cu at a maximum temperature of 210°C and pressure of 350?psi. The amount of HF and microwave pressure significantly influenced Pb, Zn and Cu recovery. Comparison between EMMA-XRF and ICP-AES showed a good correlation between Pb, Zn and Cu concentrations. Using the newly developed digestion method, Pb isotopes in lichens from the mining site were determined with an internal precision better than 0.02%. 相似文献
6.
T. P. Fischer S. Shuttleworth P. A. ODay 《Fresenius' Journal of Analytical Chemistry》1998,362(5):457-464
The accurate measurement of ultra-trace concentrations of rare metals and platinum group elements in volcanic fluids is complicated
by interferences, complex matrices, and preferential element partitioning. We analyzed condensed, high-temperature magmatic
fluids collected from Kudryavy volcano (Kurile Islands, Russia) for Be, B, Rb, Sr, Mo, Ru, Rh, Pd, Cd, W, Re, Pt, Pb, Bi,
and U using ICP-MS. The samples had three different matrices: 5 mol L–1 sodium hydroxide (NaOH, pH = 11), gas condensates of sulfuric acid (H2SO4, pH = 0), and solid elemental sulfur. Interferences and suppression/enhancement effects were investigated using standards
in concentrated NaOH and H2SO4 solutions to determine adequate dilution for sample analyses, which then required very low levels of element detection (<
1 μg L–1 for most elements). Depending on the field sampling technique of volcanic gas vents, our results show significant differences
in concentrations of some trace elements due to the precipitation of solid sulfur during gas condensation and variations in
element volatility as a function of temperature.
Received: 1 March 1998 / Revised: 1 July 1998 / Accepted: 7 July 1998 相似文献
7.
Zofia Kowalewska E. Bulska A. Hulanicki 《Fresenius' Journal of Analytical Chemistry》1998,362(1):125-129
Different methods for the determination of several metals in soils by flame atomic absorption spectrometry (FAAS) were investigated.
Different procedures for total dissolution of soil: I – HF+HClO4, H3BO3, HCl digestion (conventional heating), II – HF+HClO4, H3BO3 digestion followed by fusion with LiBO2 (conventional heating) and III – HF+HCl+HNO3, H3BO3 digestion (microwave heating), as well as a leaching procedure with HNO3+HClO4, HCl were tested and compared. For quality assessment, the certified reference material S-1 soil was used. For most of the
investigated metals, the best accuracy and precision were achieved when the procedure I or III were used. The developed procedure
was applied to the analysis of soil samples from crude oil refinery and dump of petroleum origin wastes regions.
Received: 22 Dezember 1997 / Revised: 9 February 1998 / Accepted: 12 February 1998 相似文献
8.
Summary Indirect UV detection in capillary zone electrophoresis (CZE) is frequently used for the determination of inorganic anions
and carboxylic acids. However, there are few reports on direct UV detection of these solutes in real samples. This paper describes
the use of direct UV detection of inorganic anions and organic acids in environmental samples using co-electroosmotic capillary
zone electrophoresis (co-CZE) at 185 nm. The best separation and detection of the solutes was achieved using a fused silica
capillary with an electrolyte containing 25 mM phosphate, 0.5 mM tetradecyltrimethylammonium bromide (TTAB) and 15% acetonitrile
(v/v) at pH 6.0. Four common inorganic anions (Cl−, NO2
−, NO3
− and SO4
2−) and 11 organic acids (oxalic, formic, fumaric, tartaric, malonic, malic, citric, succinic, maleic, acetic, and lactic acid),
were determined simultaneously in 15 min. Linear calibration plots for the test solutes were obtained in the range 0.02–0.5
mM with detection limits ranging from 1–9 μM depending on the analyte. The proposed method was successfully used to determine
inorganic anions and carboxylic acids in soil and plant tissue extracts with direct injection of the sample. 相似文献
9.
Comparison of microwave-assisted acid leaching techniques for the determination of heavy metals in sediments, soils, and sludges 总被引:2,自引:0,他引:2
Microwave-assisted EPA method 3051 for nitric acid leaching of environmentally key elements from sediments, soils, and sludges
was tested, and the influence of leaching temperature and time on element recovery for an estuarine sediment (CRM 277) was
investigated. The extraction efficiencies for four certified reference materials applying EPA method 3051, an optimized nitric
acid procedure, and an aqua regia (HCl/HNO3 3:1) procedure were compared. Digestions were carried out in a high-pressure microwave system offering simultaneous temperature
and pressure control for all digestion vessels employed. Eight elements (Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn) were determined
by ICP-AES and ICP-MS. Extraction efficiency strongly depended on the applied leaching parameters and varied for certain elements
among different materials when a nitric acid procedure was applied. In general, element recoveries obtained from the aqua regia procedure were superior to those obtained from nitric acid procedures and showed good agreement with the 95% confidence interval
of the certified value for most of the elements investigated.
Received: 27 March 1998 / Revised: 29 June 1998 / Accepted: 3 July 1998 相似文献
10.
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