共查询到20条相似文献,搜索用时 15 毫秒
1.
The applicability of tetramethylenedithiocarbamate (TMDTC−) and hexamethylenedithiocarbamate (HMDTC−) for colloid flotation separation of manganese in traces from fresh (spring, well and tap) water was studied. The experimental
conditions for the successful manganese separation and preconcentration before electrothermal atomic absorption spectrometric
(ETAAS) determination were optimised. Higher enrichment of manganese was achieved when a larger amount of HMDTC− is used. Applying iron(III) hexamethylenedithiocarbamate, Fe(HMDTC)3, as a precipitate collector, manganese was determined at μg/L levels singly or simultaneously with lead and zinc in 1 L of
water sample. The applicability of the proposed procedure have been verified by analyses of fresh water samples using the
method of standard addition, as well as by comparing the results obtained by ETAAS with those obtained by inductively coupled
plasma-atomic emission spectrometry (ICP-AES). The detection limit of manganese using this method is 0.025 μg/L.
Received August 30, 1999. Revision May 15, 2000 相似文献
2.
A novel sensitive and simple method for rapid and selective extraction, preconcentration and determination of iron (as its
bathophenanthroline complex) and copper (as its neocuproine complex) using octadecyl silica cartridges and dual wavelength
spectrophotometry is presented. The dual wavelength method (533 nm for the iron-bathophenanthroline and 454 nm for the copper-neocuproine
as the analytical wavelength) is used to eliminate spectral interferences. Extraction efficiency and the influence of flow
rates of sample solution and eluent, pH, amount of neocuproine, bathophenanthroline and hydroxylamine hydrochloride, type
and least amount of eluent for elution of iron and copper complexes from cartridge, break-through volume and limit of detection
are evaluated. The effects of various cationic and anionic interferences on percent recovery of iron and copper are also studied.
Extraction efficiencies >95% are obtained by elution of cartridges with minimal amount of organic solvent. Iron and copper
were determined in the range of 3–100 ng mL−1. The limits of detection are 0.98 and 1.13 ng mL−1 for iron and copper, respectively. The proposed method is applied successfully to the determination of both analytes in river,
tap and well water samples.
Author for correspondence. E-mail: yyamini@modares.ac.ir
Received September 18, 2002; accepted December 12, 2002
Published online May 5, 2003 相似文献
3.
O. E. Veveris Yu. A. Bankovskii L. L. Pelekis N. G. Aynbinder L. A. Shekhtmeyster 《Journal of Radioanalytical and Nuclear Chemistry》1971,9(1):47-53
The separation of elements by means of thiooxine is reviewed. The extraction ranges of the thiooxinates of manganese, iron,
cobalt, copper, zinc and mercury, for metal contents of 10−7–10−9g, were determined using the radioactive tracer method. Solubility values in chloroform and distribution coefficients in the
system chloroform-water were determined for mercury, zinc and iron thiooxinates. Polytetrafluoroethylene powder was used to
eliminate chloroform traces from the aqueous phase. 相似文献
4.
Citric acid was thermochemically esterified onto defatted cotton fibre to produce a carboxyl cotton chelator (CCC), which
had been used for extraction of copper prior to its determination by flame atomic absorption spectrometry. The extraction
of copper has been studied under both batch and column methods. Quantitative extraction of copper was achieved in the pH range
4–7. The time needed to extract each sample was less than 30 min by the batch method. The copper extraction capacity of CCC
was found to be 22.7 mg g−1 at optimal pH value. The elution was quantitative with 1 mol L−1 hydrochloric acid. The feasible flow rate of copper-containing solution for quantitative extraction onto the column packed
with CCC was 0.5–4.0 mL min−1, whereas for elution it was less than 1.5 mL min−1. A 100-fold extraction factor could be achieved under the optimal column conditions. The tolerance limits for common metal
ions on the extraction of copper and the time of column reuse were investigated. The proposed method has been successfully
applied for extraction and determination of copper in industrial wastewater and natural water samples. 相似文献
5.
Konstantin L. Mutaftchiev 《Mikrochimica acta》2001,136(1-2):79-82
The catalytic effect of manganese(II) on the oxidation of Naphthol Blue Black, with potassium periodate in the presence of
1,10-phenanthroline in weakly acidic media is studied. The reaction is followed spectrophotometrically by measuring the decrease
in the absorbance of the dye at 618 nm. Under the optimum conditions (3 × 10−5 mol dm−3 Naphthol Blue Black, 6 × 10−4 mol dm−3 potassium periodate, 1 × 10−4 mol dm−3 1,10-phenanthroline, 0.1 mol dm−3 acetate buffer – pH 4.0, 60 °C, 5 min) manganese(II) in the range 0.08–4 ng cm−3 can be determined by the fixed-time method with a detection limit of 0.025 ng cm−3. The influence of foreign ions on the accuracy of the results is investigated. The developed method is highly sensitive,
selective, and simple. The method was applied successfully to the determination of manganese in cucumbers, garlic cloves and
parsley leaves.
Received June 12, 2000. Revision December 12, 2000. 相似文献
6.
Soriano S Pereira Netto AD Cassella RJ 《Analytical and bioanalytical chemistry》2007,387(3):1113-1120
This paper reports the development of a microwave-assisted procedure for leaching of copper, iron, manganese, and zinc from
multivitamin/multimineral supplements by use of dilute acid before determination by flame atomic absorption spectrometry (FAAS).
A Doehlert design was used to find optimum conditions for the procedure by use of response-surface methodology. Three variables
(acid concentration in the leaching solution, irradiation time, and irradiation power) were used as factors in the optimization
study for two acids, HCl and HNO3. Final working conditions were established as a compromise between the optimum values for each analyte, taking into consideration
the robustness of the procedure. The best leaching results were obtained with HNO3 and the acid concentration, irradiation time, and irradiation power used were 0.70 mol L−1, 15 min and 360 W, respectively. The accuracy of the optimized procedure was evaluated by comparison with a well-established
closed-vessel microwave dissolution technique. 相似文献
7.
Selective Indicator Reaction for Kinetic Determination of Traces of Manganese(II), Ribavirin and Tiazofurin 总被引:1,自引:0,他引:1
Gordana A. Milovanović Mira M. Čakar Nevenka B. Vučić Milan Jokanović 《Mikrochimica acta》2000,135(3-4):173-178
In this work it was established that, in the presence of ammonium carbonate, traces of manganese(II) catalyse the oxidation
of Nile Blue A by hydrogen peroxide, which enables its kinetic determination in the concentration range from 6.6 to 65.9 ng
cm−3, the detection limit being 8.0 × 10−2 ng cm−3. Antiviral/antitumour substances modify the catalytic activity of manganese(II): 1-β-D-ribofuranosyl-1,2,4-triazole-3-carboxamide,
ribavirin, increases the catalytic effect of manganese(II), while 2-β-D-ribofuranosyl-thiazole-4-carboxamide, tiazofurin,
acts as an inhibitor. On the basis of these effects, a kinetic method for determining ribavirin concentrations from 0.5 × 10−1 to 4.0 × 10−1 μg cm−3 and tiazofurin concentrations from 0.3 to 2.6 μg cm−3 is proposed. The kinetics of the indicator reaction were studied in the presence of the substances examined, the kinetic
equations established, and the constants of the corresponding reaction rates calculated. The effect of temperature on these
reactions was also investigated. The method was applied to the determination of manganese(II) in mineral water and ribavirin
in pharmaceutical preparations.
Received December 16, 1999. Revision June 6, 2000. 相似文献
8.
An anodic stripping voltammetric procedure for the determination of Cu(II) at an in situ-plated stannum film electrode (SnFE)
was described. The results indicated that the SnFE had an attractive electroanalytical performance, with two distinct voltammetric
stripping signals for copper and stannum, and showed the superior advantage for the determination of copper compared with
the bismuth film electrode. Several experimental parameters were optimized. The SnFE exhibited highly linear behavior in the
concentration range from 1.0 to 100.0 μg L−1 of Cu(II) (r = 0.994) with the detection limit of 0.61 μg L−1 (S/N = 3), and the relative standard deviation for a solution containing 40.0 μg L−1 Cu(II) was 2.2% (n = 8). The procedure has been successfully applied for the determination of Cu(II) in lake water sample. 相似文献
9.
Constantine D. Stalikas Alexandros Ch. Pappas Miltiades I. Karayannis Panayotis G. Veltsistas 《Mikrochimica acta》2003,142(1-2):43-48
Squaric acid (1,2-dihydroxy-3,4-diketo-cyclobutene) is used in a specific reaction with Fe(III) for the spectrophotometric
determination of Fe(III) and total iron content. The optimization of the experimental parameters leads to the establishment
of a simple, fast and accurate analytical method. The analytical procedure includes mixing ammonium squarate (40 mM), prepared
in a phthalate buffer solution of pH 2.7, with the sample and measuring the absorbance at 515 nm. The molar absorptivity of
the colored product is 3.95×103 L·mol−1·cm−1, at 515 nm. Calibration graphs for Fe(III) are rectilinear for 0.5–20 mgL−1, with a detection limit of 0.3 mgL−1 and r.s.d. not exceeding 2.5%, for five replicates of a 3.0 mgL−1 standard solution. The method has been successfully applied to the determination of iron (III) and the total iron content
after quantitative oxidation of iron (II). The results for several analyzed samples when compared with those acquired by using
the FAAS technique, were found to be in satisfactory agreement.
Author for correspondence: University of Ioannina, Department of Chemistry, Laboratory of Analytical Chemistry, Ioannina 451
10, Greece. E-mail: panavelt@cc.uoi.gr
Received July 27, 2002; accepted December 20, 2002
Published online April 11, 2003 相似文献
10.
Jamshid L. Manzoori Hossein Abdolmohammad-Zadeh Mohammad Amjadi 《Mikrochimica acta》2007,159(1-2):71-78
A simple and sensitive cloud point extraction method has been developed for the preconcentration of ultra-trace amounts of
gold as a prior step to its determination by electrothermal atomic absorption spectrometry. It is based on the extraction
of gold in hydrochloric acid medium using the non-ionic surfactant polyethyleneglycolmono-p-nonylphenylether (PONPE 7.5) without adding a chelating agent. The preconcentration of a 50 mL sample solution was thus enhanced
by a factor of 200. The resulting calibration graph was linear in the range of 10–200 ng L−1 with a correlation coefficient of 0.9993. The limit of detection (3s) obtained under optimal conditions was 2.0 ng L−1. The relative standard deviation for 10 replicate determinations at a 100 ng L−1 Au level was 3.6%. The method was applied to the ultra-trace determination of gold in water and copper samples. 相似文献
11.
Y. Zhao 《Chromatographia》2000,51(3-4):231-234
Summary A new chelating reagent 2-thiophenaldehyde-4-phenyl-3-thiosemicarbazone (TAPT) has been examined for high performance liquid
chromatographic (HPLC) separations of cobalt (II), copper(II) and iron (II) or cobalt (II), nickel (II), iron (II), copper
(II) and mercury (II) as metal chelates on a C18, 5μm column (250×4 mm i.d.) The chelates were eluted isocratically with methanol: acetonitrile: water containing sodium acetate
and tetrabutylammonium bromide (TBA), and detected at 254 nm. A solvent extraction procedure was developed for simultaneous
determination of the metals with detection limits within 0.02–2.5 μ g.mL−1. The method was applied to the determination of copper, cobalt and iron in natural waters. 相似文献
12.
Determination of haloanisoles in paper samples for food packaging by solid-phase microextraction and gas chromatography 总被引:1,自引:0,他引:1
Edmar Martendal Dilma Budziak Rafael Debastiani Eduardo Carasek 《Mikrochimica acta》2007,159(3-4):229-234
A method was developed for the determination of trichloroanisole, tribromoanisole and pentachloroanisol by solid-phase microextraction
and gas chromatography in paper samples (Kraft liner, Test liner and Miolo). Four commercial SPME fibers were evaluated: Polydimethylsiloxane
(PDMS), Polyacrylate (PA), Carbowax/Divinylbenzene (CW/DVB) and Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS).
DVB/CAR/PDMS gave the best results and was therefore selected. Other variables involved in the extraction procedure were studied
and optimized, such as: sample volume, salting-out effect, temperature and extraction time, effect of organic solvent and
previous sample preparation. Optimum conditions were obtained using 20 mL of sample with 5 mol L−1 NaCl in a 40 mL vial, extraction temperature of 70 °C and sonication and extraction time of 30 and 40 min, respectively.
Detection limits ranged from 0.43 to 1.32 ng g−1 for all analytes. Recoveries between 70 and 100% were obtained and relative standard deviation was below 10% for all compounds. 相似文献
13.
Grabarczyk M 《Analytical and bioanalytical chemistry》2008,390(3):979-986
A simple and fast catalytic adsorptive stripping voltammetric procedure for trace determination of Cr(VI) in natural samples
containing high concentrations of humic substances has been developed. The procedure for chromium determination in the presence
of DTPA and nitrates was employed as the initial method. In order to enhance the selectivity vs. Cr(III) the measurements
were performed at 40°C. Interference from dissolved organic matter such as humic and fulvic acids was drastically decreased
by adding Amberlite XAD-7 resin to the voltammetric cell before the deaeration step. The whole procedure was applied to a
single cell, which allowed monitoring of the voltammetric scan. Optimum conditions for removing humic and fulvic acids due
to their adsorption on XAD-7 resin were evaluated. The use of XAD-7 resin also minimize interferences from various cationic,
anionic, and nonionic surfactants. The calibration graph for Cr(VI) for an accumulation time of 30 s was linear in the range
5 × 10−10 to 5 × 10−8 mol L−1. The relative standard deviation for determination of Cr(VI) at a concentration of 1 × 10−8 mol L−1 was 3.5% (n = 5). The detection limit estimated from 3 times the standard deviation for low Cr(VI) concentrations and an accumulation
time of 30 s was about 1.3 × 10−10 mol L−1. The proposed method was successfully applied to Cr(VI) determination at trace levels in soil samples. 相似文献
14.
Hadla S. Ferreira Walter N.L. dos Santos Raigenis P. Fiuza Joaquim A. Nbrega Sergio L.C. Ferreira 《Microchemical Journal》2007,87(2):128-131
The present work proposes a direct method based on slurry sampling for the determination of zinc and copper in human hair samples by multi-element sequential flame atomic absorption spectrometry. The slurries were prepared by cryogenic grinding and sonication of the samples. The optimization step was performed using univariate methodology and the factors studied were: nature and concentration of the acid solution, amount sample/slurry volume, sonication time, and particle size. The established experimental conditions are the use of a sample mass of 50 mg, 2 mol L− 1 nitric acid solution, sonication time of 20 min and slurry volume of 10 mL. Adopting the optimized conditions, this method allows the determination of zinc and copper with detection limits of 88.3 and 53.3 ng g− 1, respectively, and precision expressed as relative standard deviation (RSD) of 1.7% and 1.6% (both, n = 10) for contents of zinc and copper of 100.0 and 33.3 μg g− 1, respectively. The accuracy was checked and confirmed by analysis of two certified reference materials of human hair. The procedure was applied for the determination of zinc and copper in two human hair samples. The zinc and copper contents varied from 100.0 to 175.6 and from 3.2 to 32.8 μg g− 1, respectively. These samples were also analyzed after complete digestion in a closed system and determination by FAAS. The statistical comparison by t-test (95% confidence level) showed no significant difference between these results. 相似文献
15.
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
16.
Lopes IC De Souza D Machado SA Tanaka AA 《Analytical and bioanalytical chemistry》2007,388(8):1907-1914
This work describes the application of an ordinary pyrolitic graphite electrode modified by metallophthalocyanine allied to
square wave voltammetry for the study of the electrochemical behavior of the herbicide paraquat and the development of a method
for its analytical determination in natural water samples. Preliminary experiments indicated that the best responses, considering
the intensities of the current and voltammetric profile for the paraquat reduction process, were obtained when the electrode
modified by cobalt phthalocyanine was employed, which had a better catalytic activity as a result of this modification compared
with that for an unmodified electrode and electrodes modified by iron, manganese and the acid form of the phthalocyanines.
Studies of the concentration of cobalt phthalocyanine and the adsorption time showed that 1.0 × 10−4 mol L−1 cobalt phthalocyanine with an adsorption time of 10 min was sufficient to obtain reliability and stability of modification
for employment in the development of the electroanalytical procedure for paraquat determination in natural water samples.
The variation in pH of a 0.10 mol L−1 Britton–Robinson buffer solution and the square wave parameters indicated that the best conditions to reduce paraquat were
pH 7.0, a frequency of 100 s−1, a scan increment of 2 mV and a square wave amplitude of 50 mV. Under such conditions, the variation of paraquat concentrations
from 5.00 × 10−7 to 2.91 × 10−5 mol L−1 showed a linear relation, with detection and quantification limits of 26.53 and 88.23 μg L−1; those values were lower than the maximum limits for drinking water permitted by the Brazilian Environmental Council (100 μg
L−1), indicating that the method could be employed to analyze paraquat in drinking water samples. 相似文献
17.
The electrooxidative behaviour and determination of quetiapine (QTP), a dibenzothiazepine derivative and antipsychotic agent,
on a glassy carbon disc electrode was investigated using cyclic (CV), linear sweep (LSV), differential pulse (DPV) and Osteryoung
square wave voltammetry (OSWV). Fully validated DP and SW voltammetric procedures are described for the determination of QTP.
QTP in pH 3.5 acetate buffer solution presents a well-defined anodic response, studied by the proposed methods. This main
response was due to the irreversible, diffusion-controlled, one-electron and one-proton oxidation of the aliphatic nitrogen
of the piperazine ring. Under optimal conditions, a detection limit of 4.0 × 10−8 mol L−1 for DPV and 1.33 × 10−7 mol L−1 for OSWV, and a linear calibration graph in the range from 4.0 × 10−6 to 2.0 × 10−4 mol L−1 were obtained for both methods. The procedure was successfully applied to the determination of the drug in tablets, human
serum and human urine with good recoveries. The detection limits were 6.20 × 10−7 mol L−1 and 5.92 × 10−7 mol L−1 in human serum and 1.44 × 10−7 mol L−1 and 1.31 × 10−6 mol L−1 in human urine, for the DPV and OSWV method, respectively. 相似文献
18.
A novel molecularly imprinted polymer solid-phase extraction (MISPE) with flow-injection chemiluminescence (CL) was developed
for the determination of pazufloxacin mesilate (PZFX). The molecularly imprinted polymer (MIP) was synthesized by using PZFX
as the imprinting molecule. A glass tube packed the particles of the MIP was employed as MISPE micro-column, which was connected
into the sampling loop of the eight-way injection valve for on-line selective preconcentration and extraction of PZFX. The
eluent of acetonitrile:acetic acid (9:1, v:v) was used as carrier for eluting the adsorbed PZFX to react with the mixture
of cerium(IV) and sodium sulfite in the flow cell to produce strong CL. The relative intensity of CL was linear to PZFX concentration
in the range from 2.5 × 10−9 to 2.5 × 10−7 g mL−1. The limit of detection was 7 × 10−10 g mL−1 (3 σ) and the relative standard deviation for 5 × 10−8 g mL−1of PZFX solution was 3.7% (n = 7). This method has been applied to the determination of PZFX in human urine. 相似文献
19.
Tyszczuk K 《Analytical and bioanalytical chemistry》2008,390(7):1951-1956
Adsorptive stripping voltammetry is a very sensitive and selective method for determination of drugs and organic substances
in biological fluids. We have shown that determination of testosterone by adsorptive stripping voltammetry is possible using
a lead film electrode. The lead film plating process and accumulation of testosterone were performed simultaneously from an
acetate buffer solution of pH = 5.2 at a potential of −1.1 V. The measurements were carried out in undeaerated solutions.
The detection limit was 9 × 10−9 mol L−1 for an accumulation time of 120 s; the relative standard deviation for 1 × 10−7 mol L−1 testosterone was 3.8%. The proposed voltammetric procedure for determination of testosterone could be applied to its determination
in a pharmaceutical preparation and human urine samples directly without any separation steps. 相似文献
20.
A novel procedure was developed for the determination of trace cerium on the basis of anodic adsorption voltammetry of the
Ce(III)–alizarin complexon (ALC) complex at a carbon paste electrode (CPE). The procedure is convenient to determine cerium
individually in the presence of other rare earths because there is a 100 mV difference between the peak potentials of Ce(III)–ALC
and other rare earth(III)–ALC complexes in a supporting electrolyte of 0.08 M HAc–NaAc and 0.012 M potassium biphthalate (pH
4.7) when performing linear-scanning from −0.2 to 0.8 V (vs. SCE) at 100 mV/s. The second-order derivative peak currents are directly proportional to the Ce(III) concentration over
a range of 6.0 × 10−9–3.0 × 10−7 M. The detection limit is as low as 2.0 × 10−9 M (S/N = 3) for a 120 s preconcentration. An RSD of 3.5% was obtained for 15 determinations of Ce(III) at a concentration of 4.0
× 10−8 M on the same CPE surface. The method was applied successfully to the determination of cerium in samples of rare earth nodular
graphite cast iron. 相似文献