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1.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was applied for the sensitive multi-element analysis of traces and ultra-traces in geological samples. In order to prepare homogeneous targets the powdered geological samples were melted together with a lithium-borate mixture (90% Li2B4O7, 10% LiBO2) in a muffle furnace at 1050?°C. The quantification of the analysis results was carried out using the BCR-2G and BM standard reference material (SRM). The experimentally determined relative sensitivity coefficients (RSC) for both SRMs vary between 0.2 and 3 for most of the elements, whereas the relative standard deviation (RSD) of the determination (N = 3) of the concentration was 5–20%. The analysis results of LA-ICP-MS for various geological samples are in agreement with those of other methods. 相似文献
2.
Detlef Günther Albrecht v. Quadt Ronny Wirz Herve Cousin Volker J. Dietrich 《Mikrochimica acta》2001,136(3-4):101-107
Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used as a complementary technique to X-ray fluorescence
(XRF), for multi-element analysis of geological samples fused with lithium-tetraborate Li2B4O7). Different calibration strategies using external non-matrix matched reference materials were investigated. Various internal
standards were tested, including the use of Li from the flux, and the use of the naturally occurring internal standards, Si
or Ca. The use of a naturally occurring standard is not as efficient as this required a prior analysis of the samples using
XRF. The obtained values for the analysis of geological reference materials were compared with consensus literature values,
and satisfactory agreement was found. Laser pits, which were formed, had a diameter of 80 μm and 3–5 replicates on each fused
disc were measured. The reproducibility of the method was better than 10% for concentrations above 1 μg/g and better than
15% for lower concentrations. The use of Li as the internal standard offers the possibility of multi-element determinations
in geological samples, which have an unknown composition when the laser ablation analysis is carried out. However, using the
calculated stoichiometric composition of the lithium-tetraborate for the calculation of the Li concentration leads to a constant
deviation from the recommended values. Therefore, it was necessary to determine the Li concentration within each sample batch
using at least one lithium tetraborate fused geological reference material. This resulting Li concentration in the beads was
then used for all subsequent samples in a run. Limits of detection, reproducibility, deviation from reference values indicate
the potential of LA-ICP-MS for such bulk analysis without matrix matched calibration standards. 相似文献
3.
A continuous precipitation and filtration flow system for the separation of citric acid by precipitation with lead and indirect
flame atomic absorption spectrometry is proposed. The precipitate is formed by injecting the lead solution into a carrier
containing the sample and is subsequently retained on a filter. By using this reversed precipitation flow-injection configuration,
citric acid was determined in the range 2–40 μg mL–1, with a relative standard deviation of 2.9% at a sampling frequency of 60 samples h–1. This method has been applied to the determination of citric acid in fruit juices, carbonated soft drinks and sweets.
Received: 19 March 1999 / Revised: 27 May 1999 / Accepted: 31 May 1999 相似文献
4.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used as a powerful multielement analytical method
for trace analysis of geological glasses which are useful as reference materials for geochemical in-situ microanalytical work.
The quantification of the analytical results was carried out using the BCR-2G and NIST 612 glass standard reference material
(SRM). The experimentally determined relative sensitivity coefficients (RSC) for both SRMs vary between 0.2 and 3 for most
of the elements, with increasing mass an increasing of relative sensitivity coefficients was observed. The relative standard
deviation (RSD) for determination of trace element concentration of most elements (N=3) are between 2 and 10%. The determination
of trace elements in various geological glasses by LA-ICP-MS yielded a good agreement with the reference values and those
results of other trace analytical methods.
Received October 15, 1999. Revision April 14, 2000. 相似文献
5.
C. Pickhardt I. B. Brenner J. S. Becker H.-J. Dietze 《Analytical and bioanalytical chemistry》2000,368(1):79-87
Laser ablation inductively coupled plasma mass spectrometry using a quadrupole-based mass spectrometer (LA-ICP-QMS) was applied
for the analysis of powdered zeolites (microporous aluminosilicates) used for clean-up procedures. For the quantitative determination
of trace element concentrations three geological reference materials, granite NIM-G, lujavrite NIM-L and syenite NIM-S, from
the National Institute for Metallurgy (South Africa) with a matrix composition corresponding to the zeolites were employed.
Both the zeolites and reference materials were fused with a lithium borate mixture to increase the homogeneity and to eliminate
mineralogical effects. In order to compare two different approaches for the quantification of analytical results in LA-ICP-MS
relative sensitivity coefficients (RSCs) of chemical elements and calibration curves were measured using the geostandards.
The experimentally obtained RSCs are in the range of 0.2-6 for all elements of interest. Calibration curves for trace elements
were measured without and with Li or Ti as internal standard element. With a few exceptions the regression coefficients of
the calibration curves are better than 0.993 with internal standardization. NIM-G granite reference material was employed
to evaluate the accuracy of the technique. Therefore, the measured concentrations were corrected with RSCs which were determined
using lujavrite reference material NIM-L. This quantification method provided analytical results with deviations of 1–11%
from the recommended and proposed values in granite reference material NIM-G, except for Co, Cs, La and Tb. The relative standard
deviation (RSD) of the determination of the trace element concentration (n = 5) is about 1% to 6% using Ti as internal standard
element. Detection limits of LA-ICP-QMS in the lower μg/g range (from 0.03 μg/g for Lu, Ta and Th to 7.3 μg/g for Cu, with
the exception of La) have been achieved for all elements of interest. Under the laser ablation conditions employed (λ: 266
nm, repetition frequency: 10 Hz, pulse energy: 10 mJ, laser power density: 6 × 109 W/cm2) fractionation effects of the determined elements relative to the internal standard element Ti were not observed.
Received: 7 April 2000 / Revised: 25 May 2000 / Accepted: 31 May 2000 相似文献
6.
Stéphanie Loyaux-Lawniczak Jamaa Douch P. Behra 《Fresenius' Journal of Analytical Chemistry》1999,364(8):727-731
Reversed-phase ion-pair liquid chromatography is often used to analyse traces of EDTA in natural water samples. Some perturbations
due to the presence of major anions in samples, which can compete for ion pair formation with the Fe-EDTA complex used for
the detection, have been observed but never estimated and quantified. A new operational method for determining EDTA in natural
water samples is proposed by taking into account anion interactions. Qualitative and quantitative analyses of EDTA were performed
with a synthetic water at various ionic strengths. From the effect of the ionic strength controlled by CaCl2, the concentration of the counter-ion tetrabutylammonium bromide (TBA+Br–) and the methanol of the mobile phase, optimal analytical conditions were proposed for a better determination of EDTA concentration.
The limit of detection without preconcentration and the reproducibility defined as relative standard deviation were 5 μg/L
and 3.6% (n = 12), respectively. This method was applied to natural samples.
Received: 15 March 1999 / Revised: 30 March 1999 / Accepted: 31 March 1999 相似文献
7.
Jinmao You Wenjian Lao Qingyu Ou Xuejun Sun 《Fresenius' Journal of Analytical Chemistry》1999,365(6):521-528
A simple and sensitive HPLC method for the determination of hydroxyl compounds including volatile alcohols from spiked plasma,
using a fluorescent condensation agent, namely carbazole-9-N-(2-methyl)-acetyl-benzene-disulfonate (CMABS), has been developed.
A mixture of alcohols and pyridine in dichloromethane was treated with CMABS to give a quantitative yield of esters. The maximum
fluorescence emissions for the derivatized alcohols are at 365 nm (λex 335 nm). Studies on derivatization conditions indicate that alcohols react very fast with CMABS in presence of pyridine in
dichloromethane to give the corresponding fluorescent derivatives. The method, in conjunction with a multi-step gradient,
offers a baseline resolution of the common alcohol derivatives on a reversed-phase C18 column, which is more convenient and more efficient than previous methods which require the prior conversion of the carboxylic
acids to the acyl chlorides. The application of this method to the analysis of volatile alcohols in plasma was also investigated.
The LC separation shows good selectivity and reproducibility for alcohol derivatives. The relative standard deviations ?(n = 5) for 100 pmol of each alcohol are < 4%. The detection limits are at the fmol level for C1–C3 alcohols and pmol level for C4–C9 alcohols.
Received: 9 November 1998 / Revised: 3 May 1999 / Accepted: 6 May 1999 相似文献
8.
Simple and rapid analytical procedures for the ETAAS determination of Cd and Pb in plant (poplar, clover, plantain) leaves
are described. Optimal conditions are presented for the wet digestion of plant matrices with a mixture of nitric acid and
hydrogen peroxide along with optimal temperature programmes for subsequent modifier-free electrothermal determination of Cd
and Pb. Slurry preparation procedures using tetramethylammonium hydroxide or a mixture of 1 mol/L HNO3 + 1.5 mol/L H2O2 are proposed as another approach for rapid and accurate routine analysis of Cd and Pb in plant leaves. It has been found
that single standard addition can be used for quantitative determination in the case of wet digestion ETAAS and standard addition
to each analysed matrix is recommended in the case of slurry ETAAS. For all plant leaves investigated good agreement was achieved
between the concentrations determined by wet digestion ETAAS and slurry ETAAS. The wet digestion method provides relative
standard deviations for Cd ranging from 3% to 17% and for Pb from 2% to 16%. For the slurry method the RSD values are in the
range of 4–31% for Cd and 4–30% for Pb, depending for both cases on the magnitude of the measured concentrations. Validity
and versatility of the methods are verified by the analyses of standard reference materials.
Received: 17 March 1997 / Revised: 2 May 1997 / Accepted: 8 May 1997 相似文献
9.
M. ?deg?rd S. H. Dundas B. Flem A. Grimstvedt 《Fresenius' Journal of Analytical Chemistry》1998,362(5):477-482
Results of the use of a double-focusing, magnetic sector inductively coupled plasma mass spectrometer (ICP-MS) with ultraviolet
(UV) laser ablation (LA) are presented for the bulk analysis of rare earth elements (REEs) in rocks fused with Li2B4O7. The sample preparation procedure used a sample to flux weight ratio of 1 : 7, and was identical with a procedure routinely
used for X-ray fluorescence (XRF) analyses of major and minor elements in geological materials. Calibration was based on a
total of 18 international standard reference materials (SRMs), and Ba was used as an internal standard element for all REEs.
The calibration curves were constructed using a weighted regression model. The use of internal standard, without exception,
improved the correlation coefficients significantly. The 3σ detection limits were established by a blank sample of SiO2 spiked with Ba, and were in the range from 0.003 μg g–1 (159Tb) to 0.051 μg g–1 (140Ce). The use of a large set of SRMs for calibration gave a good basis for the evaluation of analytical quality, and extensive
data for calculated analytical uncertainty are presented. Instrumental precision and the repeatability of the method were
studied separately, and no significant difference in these two sets of parameters were found, indicating that the spread of
results predominantly was connected to the instrumental measurements. Repeated ablations on the surface of a disk did not
influence subsequent measurements with XRF, showing that the fused disks can be stored for future use in XRF and/or LA-ICP-MS
analysis.
Received: 12 February 1998 / Revised: 6 April 1998 / Accepted: 17 April 1998 相似文献
10.
The determination of cadmium in different samples such as coal fly ashes, soils and sediments by Graphite Furnace Atomic
Absorption Spectrometry (GFAAS) was studied. The best analytical conditions and instrumental parameters were deduced. Different
types of matrix modifiers were tested and an optimization of several conditions (pyrolysis and atomization temperatures, heating
rate, use of L’vov platform, etc.) was carried out. A mixture of 2% NH4H2PO4 + 0.4% Mg(NO3)2 in 0.5 mol L–1 HNO3 as matrix modifier provided the highest sensitivity and an efficient behaviour for the three types of samples. A detection
limit of 26 ng g–1 was achieved and other figures of merit are shown. Analytical results obtained by direct calibration using standard samples
prepared in the laboratory and by standard addition method were comparable.
Received: 6 November 1998 / Revised: 4 February 1999 / Accepted: 9 February 1999 相似文献
11.
Because multielement trace analysis by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is often limited by the lack of suitable reference materials with a similar matrix composition, a novel quantification strategy using solution calibration was developed. For mass spectrometric multielement determination in geological samples a quadrupole-based LA-ICP-MS is coupled with an ultrasonic nebulizer (USN). In order to arrange matrix matching the standard solutions are nebulized with a USN during solution calibration and simultaneously a blank target (e.g. lithium borate) is ablated with a focused laser beam. The homogeneous geological samples were measured using the same experimental arrangement where a 2% nitric acid is simultaneously nebulized with the USN. Homogeneous targets were prepared from inhomogeneous geological samples by powdering, homogenizing and fusing with a lithium borate mixture in a muffle furnace at 1050 degrees C. Furthermore, a homogeneous geological glass was also investigated. The quantification of analytical results was performed by external calibration using calibration curves measured on standard solutions. In order to compare two different approaches for the quantification of analytical results in LA-ICP-MS, measured concentrations in homogeneous geological targets were also corrected with relative sensitivity coefficients (RSCs) determined using one standard solution only. The analytical results of LA-ICP-MS on various geological samples are in good agreement with the reference values and the results of other trace analytical methods. The relative standard deviation (RSD) for trace element determination (N = 6) is between 2 and 10%. 相似文献
12.
A. Navas Díaz F. G. Sanchez M. C. Torijas J. Lovillo 《Analytical and bioanalytical chemistry》1999,365(6):537-540
A methodology for the determination of lipase, based on the coupled processes of energy transfer and enhancement of the chemiluminescence
of the luminol-H2O2-horseradish peroxidase (HRP) system has been developed. Fluorescein diacetate (FDA) was hydrolyzed to fluorescein by the
action of the enzyme lipase, and this compound acted as an enhancer of the chemiluminescent process and acceptor of the chemiluminescent
emission from the luminol-H2O2-HRP system. By measuring the transferred emission to fluorescein at 525 nm, lipase (range 0.2–1.5 U/mL, RSD 2.3%) was determined.
This methodology permited the determination of every compound of the system, thus, H2O2 (range 0.5–2 mM, RSD 6.9%) and HRP (range 5.5–49.5 U/mL, RSD 3.6%) could also be determined. Lipase was determined in rabbit
serum with 96.7 ± 3.3% and 102.9 ± 5.4% recoveries for two different lipase concentrations. Besides, H2O2 was determined in the disinfectant solution for contact lenses.
Received: 1 March 1999 / Revised: 6 May 1999 / Accepted: 12 May 1999 相似文献
13.
Carola Pickhardt J. S. Becker Hans-Joachim Dietze 《Analytical and bioanalytical chemistry》2000,368(2-3):173-181
Because multielement trace analysis by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is often limited by the lack of suitable reference materials with a similar matrix composition, a novel quantification strategy using solution calibration was developed. For mass spectrometric multielement determination in geological samples a quadrupole-based LA-ICP-MS is coupled with an ultrasonic nebulizer (USN). In order to arrange matrix matching the standard solutions are nebulized with a USN during solution calibration and simultaneously a blank target (e.g. lithium borate) is ablated with a focused laser beam. The homogeneous geological samples were measured using the same experimental arrangement where a 2% nitric acid is simultaneously nebulized with the USN. Homogeneous targets were prepared from inhomogeneous geological samples by powdering, homogenizing and fusing with a lithium borate mixture in a muffle furnace at 1050?°C. Furthermore, a homogeneous geological glass was also investigated. The quantification of analytical results was performed by external calibration using calibration curves measured on standard solutions. In order to compare two different approaches for the quantification of analytical results in LA-ICP-MS, measured concentrations in homogeneous geological targets were also corrected with relative sensitivity coefficients (RSCs) determined using one standard solution only. The analytical results of LA-ICP-MS on various geological samples are in good agreement with the reference values and the results of other trace analytical methods. The relative standard deviation (RSD) for trace element determination (N = 6) is between 2 and 10%. 相似文献
14.
Irina Karadjova Julijana Cvetković Trajče Stafilov Sonja Arpadjan 《Central European Journal of Chemistry》2007,5(3):739-747
The parameters of analytical procedures developed for direct ETAAS determination of Pb in wine are discussed. Atomic absorption
spectrometers based on transversal and longitudinal Zeeman effect, wall and integrated platform atomization with two main
approaches: (i) measurements in the presence of modifier and (ii) measurements without using any modifier are compared. The
optimal temperature programs are defined according to the pre-treatment and atomization curves constructed in the presence
of different types of wines. For all investigated instrumental systems, 1:1 dilution of wine sample with 0.2 mol L−1 HNO3 is recommended. Matrix interferences observed, call for standard addition calibration method for Pb quantification in wines.
The detection limit (3σ) achieved for wine diluted in the ratio of 1:1 varied from 0.8 to 1.9 μg L−1 depending on the instrument used. The relative standard deviation for the concentration range of 10 to 80 μg L−1 Pb in wine is typically between 4–8%. The accuracy of the analytical procedures recommended was confirmed by comparing the
results obtained with those found for wine samples previously digested with HNO3-H2O2 mixture, by added/found method and by parallel analysis using different instruments. A total of 66 wine samples from different
regions of Macedonia were analyzed.
相似文献
15.
Franziska Nehring Dorrit E. Jacob Matthias G. Barth Stephen F. Foley 《Mikrochimica acta》2008,160(1-2):153-163
Trace element determination in rocks by fusion on an iridium strip heater followed by LA-ICP-MS analysis of the glass beads
is extended here to SiO2-rich rocks; rapid fusion of samples with >55 wt% SiO2 is facilitated by dilution by high purity MgO. The method developed here can rapidly and accurately determine numerous trace
elements in a large range of rock compositions in a short time (about 50 samples/day). Systematic evaluation for a large range
of rock compositions (natural rocks and reference materials AGV-2, GSP-2, JG-1a) with SiO2 contents between 45 and 80 wt% shows that reproducibility and accuracy within 10% can be routinely achieved for most of the
28 trace elements investigated (Rb, Sr, Cs, Ba, Ti, Zr, Hf, Nb, Ta, Sc, V, Cr, Ni, Pb, Th, U, REE). The 40 mg sample size
is smaller than for XRF, INAA or solution-ICP-MS, detection limits are lower, and trace element palettes more complete than
XRF and INAA. This microchemical method is thus attractive for the analysis of all natural geological materials as well as
for experimental applications with small samples. Samples with SiO2-contents >55 wt% require hot and long melting to achieve homogeneous glasses and eliminate all residual minerals, particularly
refractory accessory phases. Melting conditions of 1600 °C and 20 s for samples are recommended for SiO2 contents between 55 and 70 wt%, whereas 1800 °C and 20–30 s are often required for samples with >70 wt% SiO2. Problems are encountered for Pb and Cs due to volatilization on the Ir strip, for Sc due to interferences, and Zr and Hf
due to their sequestration in refractory accessory minerals.
Correspondence: Franziska Nehring, Department of Geosciences, University of Mainz, Becherweg 21, 55099 Mainz, Germany 相似文献
16.
J. M. Garrigues Z. Bouhsain S. Garrigues M. de la Guardia 《Analytical and bioanalytical chemistry》2000,366(3):319-322
A new procedure has been developed for the FT-IR determination of caffeine in roasted coffee samples. The method involves
wetting the coffee samples with a 0.25 M aqueous NH3 solution, extracting the caffeine with CHCl3, and measuring absorbance at 1659 cm–1 using a baseline established between 1900 and 830 cm–1. The procedure proposed is fast, only requiring a total extraction time of 16 min for each sample, and provides a drastic
reduction of the organic solvent consumed, from the 200 mL diethyl ether and 50 mL CHCl3 required for each sample by the reference chromatographic UV-spectrometric determination to only 5 mL CHCl3. The method provides a limit of detection of the order of 3 mg L–1 caffeine and a relative standard deviation of 0.4% for 3 independent analyses of a sample containing 18.6%mg/g caffeine.
The accuracy of the FT-IR procedure was evaluated from recovery experiments on spiked samples providing values from 94.4 to
100.1% and from the comparison of results found for a series of commercial samples, by both FT-IR and the official reference
procedure.
Received: 9 July 1999 / Revised: 23 September 1999 / /Accepted: 24 September 1999 相似文献
17.
Three simple and sensitive colorimetric methods (A–C) for the determination of melatonin in bulk samples and in pharmaceutical
formulations are described. They are based on the formation of coloured species by reaction of ninhydrin with the drug (method
A, λmax 397 nm) by oxidation of the indol moiety in melatonin with potassium persulphate (method B, λmax 450 nm) or by reduction of osmium (VIII) (method C, λmax 516 nm). Regression analysis of Beer-Lambert plots showed good correlations in concentration ranges between 0.8–14.2, 70.0–140.0
and 2.0–40.0 μg/mL for methods A, B and C, respectively. The molar absorptivity, Sandell sensitivity and detection limit were
calculated. For more accurate analysis, Ringbom optimum concentration ranges were calculated. The validity of the proposed
methods was tested by analysing pharmaceutical formulations containing melatonin. The relative standard deviations were ≤ 0.95%
with recoveries 99.0–101.33%.
Received October 20, 1999. Revision February 10, 1999. 相似文献
18.
Carlos E. C. Magalhães Éder C. Lima Francisco J. Krug Marco A. Z. Arruda 《Mikrochimica acta》1999,132(1):95-100
A method for direct analysis of tea and coffee samples by using electrothermal atomic absorption spectrometry is described.
Coffee and tea from different sources were analyzed without digestion step. For slurry analyses the samples were ground, sieved
at 105 μm and then suspended in 0.2% v/v HNO3 and 10% v/v Triton X-100 medium. For liquid phase aluminium determination the samples were prepared in the same way and only
the liquid is introduced directly into the graphite furnace. Calibration was performed by aqueous standards for both cases
and the determinations were carried out in the linear range between 50 and 250 μg L−1. The characteristic mass of aluminium and the detection limit were 45 pg and 2 μg L−1, respectively. Using a typical 0.1% m/v coffee slurry sample, the relative standard deviation of measurements (n=15) for
repeatability was about 8.2%.
Received December 27, 1998. Revision March 18, 1999. 相似文献
19.
Synthesis and flocculation performance of graft and random copolymer microgels of acrylamide and diallyldimethylammonium chloride 总被引:2,自引:0,他引:2
Graft (from linear homopolymers) and random (from a linear random copolymer) copolymer microgels of diallyldimethylammonium
chloride (DADMAC) and acrylamide were synthesized via a free-radical mechanism using a γ-radiation technique. These copolymer
microgels were evaluated as flocculants on a model dilute TiO2 colloid suspension using a turbidimeter and a disc centrifuge photosedimentometer, and their performances were compared with
the linear homopolymers and their blends. It was found that microgels produced after an appropriate irradiation time showed
improved flocculation behavior over their nonirradiated linear counterparts. The graft microgels performed better than the
corresponding random microgels. For a γ-radiation dosage of 100 krad/h, the graft microgels obtained by irradiating a 30%
DADMAC (by weight) homopolymer blend for 3 h showed the maximum reduction in the relative turbidity of the TiO2 suspension as well as the largest fraction of larger particles flocculated.
Received: 18 May 1999 Accepted in revised form: 1 June 1999 相似文献
20.
Ottinger F Kroslakova I Hametner K Reusser E Nesper R Günther D 《Analytical and bioanalytical chemistry》2005,383(3):489-499
Single crystals of new nitridosilicates and nitridoaluminosilicates with excellent R values in X-ray investigations were analysed quantitatively using 30 to 60 μm single-spot LA-ICP-MS. Significant discrepancies
between expected and measured chemical composition could not be explained by the crystallographic data. High spatial resolution
analysis using electron probe microanalysis (EPMA, 10 μm) leads to the discovery of inhomogeneities in the crystalline material.
The application of standard single-spot LA-ICP-MS with a spatial resolution of 30 to 60 μm is not suitable for the analysis
of these crystals as the existing inhomogeneities dominate and alter the determined concentrations. However, owing to the
better detection capabilities, a scanning LA-ICP-MS procedure enables a more representative analysis of single crystals of
Ca5Si2Al2N8 than single-spot LA-ICP-MS as a result of a larger sampling volume. It is highly likely that these impurities consist of
amorphous, vitreous phases as powder diffraction X-ray data indicates the existence of a significant fraction of an X-ray
amorphous material besides crystalline silicates. These microdomains contain less aluminium, silicon and calcium or are nearly
free of aluminium, which explains the detected discrepancies in the chemical composition. 相似文献