共查询到20条相似文献,搜索用时 31 毫秒
1.
Norbert Szoboszlai Erzsébet Andrási Zsolt Ajtony Ivett Császma 《Mikrochimica acta》2001,137(1-2):81-86
A method is reported for measuring Se and Sn in human brain tissue. The patients from whom the samples were taken had no
diseases in their central nervous system. Microwave energy was applied to digest the brain samples. The digested samples were
analyzed without dilution by transversely heated graphite atomizer for atomic absorption spectrometry with longitudinal Zeeman
background correction. The dependence of integrated absorbance on various chemical modifiers has been examined. The most appropriate
technique proved to be 5 μl sample injection using 20 μg prereduced palladium-nitrate for Se determination, and 20 μl sample
injection applying 10 μg palladium-nitrate + 3 μg magnesium-nitrate for the measurements of Sn. The optimal temperature program
was found to be 1200 °C pyrolysis and 2100 °C atomisation temperature for Se and 1500 °C pyrolysis and 2300 °C atomisation
temperature for Sn. Accuracy of the applied techniques was tested by the analysis of standard reference materials. The precision
was ±5% for Se and ±10% for Sn. The range of recovery values was 85–95% for Se and 95–105% for Sn. The mean Se concentrations
in the investigated brain parts ranged from 200 to 700 ng/g, while the Sn concentrations were between 20 and 300 ng/g dry
weight.
Received October 3, 2000. Revision February 1, 2001. 相似文献
2.
A simple and direct spectrophotometric method has been developed for the determination of cobalt(II) using N,N′-Bis(2-aminobenzoyl)ethylenediamine
(Baben). The method is based on the colour reaction between Baben and cobalt(II) in borax buffer (pH 9.2). The studies are
carried out at 470 nm at which the calculated value of molar absorptivity is found to be 1.102 × 104 L mol−1 cm−1. The system obeys Beer’s law over a wide range of concentration (2–20 μg/ml). The effect of interfering ions has been studied
and the method was applied to the determination of cobalt in water, industrial effluents and in alloys and the results were
highly satisfactory.
Received May 8, 2000. Revision January 30, 2001. 相似文献
3.
The molecular interaction between sildenafil citrate as electron donor and each of iodine; 7,7,8,8-tetracyanoquinodimethane
(TCNQ); 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ); tetracyanoethylene (TCNE); 2,4,7-trinitro-9-fluorenon (TNF); chloranilic
acid (CLA); chloranil (CL) and bromanil (BL) as acceptors have been investigated spectrophotometrically. Different variables
affecting the reaction were studied and optimized. Beer’s law was obeyed in a concentration limit of 10–260 μg/mL for sildenafil
citrate. For more accurate analysis, Ringbom optimum concentration range was found to be between 20–240 μg/mL. The limits
of detection and determination were calculated and found to be 1.5 and 5.2 μg/mL, respectively. The standard deviations were
calculated for different concentrations of sildenafil citrate using various acceptors. A Job’s plot of the absorbance versus
the molar ratio of the sildenafil citrate to each of acceptors under consideration indicated (1:1) ratio. The proposed methods
were found to be rapid, accurate, precise and sensitive and could be applied for determination of sildenafil citrate in pharmaceutical
dosage forms (Viagra) without interferences from common additives encountered.
Received August 30, 2000. Revision January 5, 2001. 相似文献
4.
Jadwiga Opydo 《Mikrochimica acta》2001,137(3-4):157-162
Necessary conditions were established for simultaneous nickel and cobalt determination in environmental samples, such as
oak wood and soil, based on cathodic adsorptive stripping voltammetry. Ni(II) and Co(II), complexed with dimethylglyoxime,
were determined using a hanging mercury drop electrode. Optimum conditions were found to be: accumulation time 90 s, accumulation
potential −0.80 V vs. SCE, supporting electrolyte 0.2 mol dm−3 ammonia-ammonium chloride buffer (pH = 9.4) + 0.05 mol dm−3 NaNO2 and dimethylglyoxime 2 × 10−4 mol dm−3. A linear current-concentration relationship was observed up to 7.51×10 −7 mol dm−3 for Ni(II) and 7.0 × 10−7 mol dm−3 for Co(II). Excess amounts of zinc(II) interfering with cobalt peaks were masked by complexation with EDTA. Wood and soils
were mineralized by applying a microwave digestion system, using the mixtures H2O2 + HNO3 or HNO3 + HF, respectively. The developed procedure was tested by analysing international reference materials (BCR 62 Olive Leaves
and GBW 08302 Tibet Soil). The developed procedure was used to determine pollution of oak stand with nickel and cobalt in
different regions of Poland.
Received August 10, 2000. Revision May 22, 2001. 相似文献
5.
Kiyohisa Ohta Hiroya Uegomori Syn-ichi Itoh Takayuki Mizuno 《Microchemical Journal》1997,56(3):343-351
Atomization characteristics of chromium have been studied by electrothermal atomic absorption spectrometry with a molybdenum tube atomizer. The appearance temperature (Tapp) of chromium nitrate was 1300°C. TheTappwas independent of the heating rate of atomizer, but the temperature at the peak of the Cr AA signal increased with the heating rate. A sensitive absorption chromium signal was obtained in pure argon purge gas. The chromium signal decreased as the ratio of hydrogen in the purge gas increased. The optimal gas flow rate was Ar 480 ml min−1+ H220 ml min−1because of the avoidance of oxidation of the atomizer. The absolute characteristic mass (the mass of element giving 0.0044 abs.) of chromium by the atomizer was 0.35 pg and the detection limit was 23 pg ml−1(3S/N). The interferences caused by large amounts of interferents were evaluated. The addition of thiourea served to eliminate the severe interferences. The accuracies of the recommended method were considered almost satisfactory for the determination of chromium in biological materials, compared with the certified values of NIST materials. The recovery of spiked chromium in biological materials was in the range from 93.5 to 102%. 相似文献
6.
Theodosios S. Sikalos Yannis M. Arabatzis Mamas I. Prodromidis Panayotis G. Veltsistas Miltiades I. Karayannis 《Mikrochimica acta》2000,135(3-4):197-201
In this work a kinetic spectrophotometric method for the determination of trace amounts of vanadium is presented. The method
is based on the catalytic effect of the vanadium(V) on the reaction between diphenylamine (DPhA) and hydrogen peroxide in
a concentrated solution of formic acid. The formation of the deep-blue oxidation product is followed by a filter spectrophotometer,
equipped with an optical fiber assembly, on line with a PC provided with the suitable software. The measurements were taken
at 583 nm, with an immersed type cell of 1 cm light path length. The optimization of the operating conditions regarding concentrations
of the reagents, temperature and interferences are also investigated. The working curve is linear over the concentration range
0.40–4.0 μg/ml vanadium(V). The relative standard deviation for a standard solution of 0.6 μg/ml of vanadium is 0.5% (n = 5).
The proposed method proved highly sensitive, selective and relatively rapid for the assay of vanadium, at low level of 0.40 μg/ml
without any pre-concentration step. The method was applied to alloys and cosmetics samples. The results were compared to those
received with a reference method. Good agreement was attained, with a mean error of 0.5%.
Received February 25, 2000. Revision May 15, 2000. 相似文献
7.
Leonardo Sena Gomes Teixeira Antônio Celso Spínola Costa Júlio César Rosa Assis Sérgio Luis Costa Ferreira Mauro Korn 《Mikrochimica acta》2001,137(1-2):29-33
A new sensitive method exploiting solid-phase spectrophotometry is proposed for the determination of cobalt in pharmaceutical
preparations. The chromogenic reagent 1-(2-thiazolylazo)-2-naphthol (TAN) was immobilized on C18 bonded silica loaded into
a home-made cell with 1.5 mm of optical path for cobalt determination. Cobalt(II) reacts with TAN on C18 material, at pH 6.0–7.5,
to give a coloured complex which has maximum absorption at 572 nm. In this way, the sample was passed through the cell and
Co(II) ions were quantitatively retained on the solid-phase. After the direct measurement of light-absorption in the solid
phase, only the cobalt was eluted with 0.1 mol L−1 hydrochloric acid. The cell was washed with water and then another sample solution could be passed through the cell. The
procedure allowed the determination of cobalt in the range of 10–160 μg L−1 with coefficient of variation of 4.7% (n=10) and apparent molar absorptivity of 2.62 × 106 L mol−1 cm−1 using sample volume of 3-mL.
Received May 15, 2000. Revision August 28, 2000. 相似文献
8.
A new sample insertion device for the stabilized capacitive plasma (SCP) has been developed, which enables it to analyze
dry residues of micro amounts of liquid samples. Insertion was applied into an SCP as plasma source because of its good stability
and excitation properties as well as its low instrument and operation costs. The plasma is sustained at a frequency of 27.12 MHz
and an RF power of 150 W. For analysis the liquid samples are positioned at the tip of a quartz rod with the aid of a μL syringe.
Then the sample is dried and the sampling rod inserted into the plasma. After optimization of the carrier gas flow (5 L/h)
and the sample volume (20 μL) the detection limit for Pb with Ar as plasma gas is 200 pg.
By further improving the guidance of the insertion detection limits for Pb, Cu, Cd and Mg in the 1 to 30 ng/mL range or 20
to 600 pg range absolute were obtained. It was found that the detection limits in the case of He are better than those obtained
with Ar. The matrix interferences caused by changes in the concentration of the easily ionizable element Na were found to
be below 10% for Na concentrations of up to 0.45 μg/mL. Ethanol concentrations of up to 14% in the analyte solutions did not
cause any interferences.
Received December 17, 1998. Revision June 4, 1999. 相似文献
9.
Beltrami D Calestani D Maffini M Suman M Melegari B Zappettini A Zanotti L Casellato U Careri M Mangia A 《Analytical and bioanalytical chemistry》2011,401(4):1401-1409
An integrated approach based on the use of inductively coupled plasma mass spectrometry (ICP-MS) and scanning electron microscopy
(SEM) for the qualitative and quantitative analyses of metal particles in foods was devised and validated. Different raw materials
and food products, like wheat, durum wheat, wheat flour, semolina, cookies, and pasta were considered. Attention was paid
to the development of sample treatment protocols for each type of sample to avoid potential artifacts such as aggregation
or agglomeration. The analytical protocols developed followed by ICP-MS and SEM investigations allowed us the quantitative
determination and the morphological and dimensional characterization of metal nano- and microparticles isolated from the raw
materials and finished food products considered. The ICP-MS method was validated in terms of linearity (0.8–80 μg/g and 0.09–9 μg/g
for Fe and Ti, respectively), quantification limits (0.73 μg/g for Fe and 0.09 μg/g for Ti), repeatability (relative standard
deviation (RSD) % equal to 10% for Fe and 20% in a wheat matrix as an example), and extraction recoveries (93 ± 2–101 ± 2%).
Validation of the scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDS) measurements was performed working
in a dimensional range from 1 to 100 μm with an estimated error in the size determination equal to 0.5 μm. ICP-MS data as
well as SEM measurements showed a decrease in the concentration of metal particles from wheat to flour and from durum wheat
to semolina samples, thus indicating an external contamination of grains by metal particles. These findings were confirmed
by environmental SEM analysis, which allowed investigation of particles of lower dimensions. Generally, the largest number
of particles was found in the case of iron and titanium, whereas particles of copper and zinc were only occasionally found
without any possibility of quantifying their number. 相似文献
10.
I. López-García E. Navarro P. Viñas M. Hernández-Córdoba 《Analytical and bioanalytical chemistry》1997,357(6):642-646
A method is proposed for the determination of Pb, Cd and Tl in cements by ETAAS. The samples are suspended in a medium containing
10% v/v ethanol and 1% v/v both conc. nitric and hydrofluoric acids and are directly introduced into the electrothermal atomizer.
The drying stage is performed by programming a 400 °C temperature, a ramp time of 5 s and a hold time of 30 s on the power
supply to the atomizer. No ashing step is used. Atomization is carried out at 2100, 1800 and 1700 °C for Pb, Cd and Tl, respectively.
For Cd determination, ammonium dihydrogen phosphate is added to the suspension medium. No modifier other than hydrofluoric
acid is required for the Pb and Tl determination. It is shown that the results obtained by using direct calibration with aqueous
standards for five commercial samples agree with those found by means of the standard additions method.
Received: 29 March 1996/Revised: 24 May 1996/Accepted: 30 May 1996 相似文献
11.
Ali Eftekhari 《Mikrochimica acta》2003,141(1-2):15-21
The electrocatalytic activity of an aluminum microelectrode modified with cobalt hexacyanoferrate film is described. A simple
method was used for the preparation of the modified microelectrode. The modified microelectrode exhibits good electrocatalytic
properties for electrochemical reduction of hydrogen peroxide. The effect of solution pH and applied potential on the electrocatalytic
properties of the modified microelectrode is investigated. The results show that the best potential for the detection of hydrogen
peroxide is 0.0 vs. SCE for better response and decrease of interferences. Due to the microelectrode scale, it can be used for the determination
of small amounts of H2O2. The calibration plot is linear up to 1.7 mM (r = 0.988) with a response time of 5.1 s. The detection limit of the microelectrode as H2O2 sensor is 2 × 10−7 M. The sensivity of the H2O2 sensor is 225.6 nA mmol−1 and RSD of this sensor is less than 2.3%. In addition, effects of possible interferences and possibility of the sensor for
real samples is investigated. The present work shows the potential of the proposed method for the fabrication of modified
electrodes, as it can be used to employ for different purposes in micro scale.
Received June 20, 2001; accepted June 14, 2002 相似文献
12.
Andreas Rahm Evgeni M. Kaidashev Heidemarie Schmidt Mariana Diaconu Andreas Pöppl Rolf Böttcher Christoph Meinecke Tilman Butz Michael Lorenz Marius Grundmann 《Mikrochimica acta》2006,153(1-2):21-25
A flow injection chemiluminescence method is proposed for the determination of cobalt, based on the strong catalytic effect
of Cobalt(II) (1,10-phenanthroline)3 complex on the lucigenin-periodate reaction in alkaline medium. Under the optimum experimental conditions, the chemiluminescence
signal responded linearly to the concentration of cobalt(II) in the 1.0 × 10−9–3.0 × 10−7 g mL−1 range with a detection limit of 4.4 × 10−10 g mL−1 cobalt(II). The relative standard deviation for the determination of 5.0 × 10−8 g mL−1 of cobalt was 2.3% in eleven replicated measurements. The method was successfully applied to the determination of cobalt(II)
in pharmaceutical preparations. 相似文献
13.
A differential pulse voltammetric method for the determination of nitrate has been described, which is applicable to the
analysis of natural water samples with nitrate levels greater than 2.8 × 10−6 M. A reduction peak for the nitrate ions at a freshly copper plated glassy carbon electrode was observed at about −0.50 V
vs Ag ∣AgCl∣KClsatd electrode in a solution of 2.0 × 10−2 M Cu2+, 0.5 M H2SO4 and 1.0 × 10−3 M KCl and exploited for analytical purposes. The working linear range was established by regression analysis and found to
extend from 2.8 ×10−6 M to 8.0 × 10−5 M. The proposed method was applied for the determination of nitrate in natural waters. The detection limit of the method
was 2.8 × 10−6 M and the sensitivity was 0.9683 A·L/mol. The possible interferences by some ions such as phosphate, nitrite and some halides
were determined and found to lead to shifts of the peak position and increasing the peak heights.
Received March 15, 1999. Revision July 9, 1999. 相似文献
14.
A novel catalytic procedure for zirconium was proposed based on Zr(IV) catalyzed oxidation of gallocyanine by hydrogen peroxide
in hexamethylene tetramine-hydrochloric acid buffer medium. The calibration graph is linear for 0–110 ngċml−1, and the detection limit is 0.4 ngċml−1 Zr(IV). Most foreign ions do not interfere with the determination, except for Cu2+, Fe3+ and Cr(VI). The interferences of Cu2+ and Fe3+ could be eliminated by masking with EDTA and mannitol, and that of Cr(VI) by reducing to Cr(III) with ascorbic acid. The
typical features of this procedure are that it is sensitive for zirconium, and the determination could be carried out at room
temperature. It had been used to the determination of zirconium in zirconium bronze, simulated samples and a certified reference
material. The recoveries were 98.6 ∼ 102%, and relative standard deviations (R.S.D.) were 0.9 ∼ 1.5%, respectively.
Received September 12, 1999. Revision April 10, 2000. 相似文献
15.
In the present study, the determination of arsenic, lead, cadmium, chromium, cobalt, copper, nickel, mercury and zinc in
various cloth samples produced in Kayseri-Turkey was performed after extraction with artificial sweat solution and decomposition
with nitric acid. TXRF is shown to be suitable for the determination of 7 trace elements, down to the 0.001 (cobalt) to 0.004
(copper) mg/kg level in textile extract except for mercury and cadmium. The extractable part of the toxic metals by artificial
sweat solution is relatively low. In a few extracts the concentration values of Pb and Ni have exceeded their critical values
of 0.2 mg/kg for lead and 1.0 mg/kg for nickel given by ?ko-Tex and determined for babys cloths. In addition, it was observed
that the element pattern of textile samples resembled ‘finger print type’, TXRF-spectra. This technique can also be used for
the identification of textile sample in forensic investigation.
Received April 16, 2001 Revision October 1, 2001. 相似文献
16.
Saadia M. El-Ashry Fathalla Belal Mohamed M. El-Kerdawy Dalia R. El Wasseef 《Mikrochimica acta》2000,135(3-4):191-196
A simple and sensitive spectrophotometric method is described for the determination of some phenolic antibiotics namely:
cefadroxil, amoxicillin and vancomycin. The method is based on the measurement of the orange yellow species produced when
the drugs are coupled with diazotized benzocaine in triethylamine medium. The method is applicable over the range of 0.8–12 μg/ml
for cefadroxil, 2–16 μg/ml for amoxicillin and 2–18 μg/ml for vancomycin. The formed compounds absorb at 455 nm for both cefadroxil
and amoxicillin and at 442 nm for vancomycin. The proposed method has detection limits of 0.018 μg for cefadroxil, 0.0034 μg
for amoxicillin and 0.0156 μg for vancomycin.
The stoichiometric ratio for the studied compounds was found to be 1:1 and a proposal of the reaction pathway was made. The
proposed method was applied for the analysis of the cited drugs in their pharmaceutical preparations. The results are in good
agreement with those obtained by the official methods.
Received February 7, 2000. Revision June 14, 2000. 相似文献
17.
İpek Menemenlioğlu Deniz KorkmazO. Yavuz Ataman 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007
The analytical performance of a miniature quartz trap coupled with electrochemical hydride generator for antimony determination is described. A portion of the inlet arm of the conventional quartz tube atomizer was used as an integrated trap medium for on-line preconcentration of electrochemically generated hydrides. This configuration minimizes transfer lines and connections. A thin-layer of electrochemical flow through cell was constructed. Lead and platinum foils were employed as cathode and anode materials, respectively. Experimental operation conditions for hydride generation as well as the collection and revolatilization conditions for the generated hydrides in the inlet arm of the quartz tube atomizer were optimized. Interferences of copper, nickel, iron, cobalt, arsenic, selenium, lead and tin were examined both with and without the trap. 3σ limit of detection was estimated as 0.053 μg l− 1 for a sample size of 6.0 ml collected in 120 s. The trap has provided 18 fold sensitivity improvement as compared to electrochemical hydride generation alone. The accuracy of the proposed technique was evaluated with two standard reference materials; Trace Metals in Drinking Water, Cat # CRM-TMDW and Metals on Soil/Sediment #4, IRM-008. 相似文献
18.
Determination of Trace Elements in Super Alloy by ICP-MS 总被引:1,自引:0,他引:1
A method is described for determination of 14 trace elements in super alloy certified reference material. Inconel 718 by ICP-MS. The interferences were investigated in detail. By using appropriate settings of the operational parameters and
correcting interferences the elements without interference free isotopes were also analyzed. Non-spectral interference to
the analytes was studied. No matrix separation or any other sample pretreatment but acid dissolution was made. 14 trace elements
(B, Sc, Ga, Ge, In, Sn, Sb, Te, Hf, Ag, Ce, Tl, Pb and Bi) were analyzed by matrix matched standard solution calibration and
using Rh as internal standard. Good agreement was achieved between the found levels and the certified values for most of the
elements. The RSD (n = 4) of the determination values of Ce was lower than 20%, and RSD of the other 13 elements was lower
than 10%.
Received July 21, 2000. Revision May 29, 2001. 相似文献
19.
L. D. Martinez M. Baucells E. Pelfort M. Roura R. Olsina 《Analytical and bioanalytical chemistry》1997,357(7):850-852
An accurate procedure for the elimination of iron interferences in the determination of selenium in geological materials
by the Hydride Generation – Inductively Coupled Plasma Atomic Emission Spectrometry technique (HG-ICPAES) is proposed. A selective
removal of iron is achieved by on-line incorporation of a microcolumn filled with strongly acidic cation exchange resin (Dowex
50W-X8). The microcolumn manifold used was interfaced with the hydride generation manifold by a flow injection sample injection
valve. After the removal of the iron, a 500 μl sample was injected into a carrier stream of water. This was merged with hydrochloric
acid and sodium tetrahydroborate in order to generate the corresponding selenium hydride. The system was found to have a limit
of detection of 0.4 ng ml-1 and a relative standard deviation of 2% for 20 ng ml-1 selenium. The application of the method on different Geochemical Standard Reference Samples demonstrated that results were
statistically indistinguishable from certified values.
Received: 7 March 1996 / Revised: 30 May 1996 / Accepted: 4 June 1996 相似文献
20.
Single-wall carbon nano-tubes were used to modify the surface of a glassy carbon electrode (GC) and applied in the determination
of folic acid with voltammetry. The experiments demonstrated that the presence of a carbon nano-tube film on the electrode
greatly increased the reduction peak current of folic acid. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were
used in a comparative investigation of the electrochemical reduction of folic acid with the film electrode. Effects of pH
on the peak current and the peak potential were studied in the pH range of 4.0–8.0 with Britton-Robinson buffer solution.
The reduction peak current was found to be linearly related to folic acid concentration over the range of 1 × 10−8 to 1 × 10−4 mol L−1 with a detection limit of 1 × 10−9 mol L−1 after 5 min accumulation. The film electrode provides an efficient way for eliminating interferences from some inorganic
and organic species in the solution. The high sensitivity, selectivity and stability of the film electrode demonstrate its
practical application from a simple and rapid determination of folic acid in tablets. 相似文献