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1.
A new chemiluminescence (CL) method combined with flow injection technique is described for the determination of Cr(III) and
total Cr. It is found that a strong CL signal is generated from the reaction of Cr(III), lucigenin and KIO4 in alkaline condition. The determination of total Cr is performed by pre-reduction of Cr(VI) to Cr(III) by using H2SO3. The CL intensity is linearly related to the concentration of Cr in the range 4.0 × 10−10–1.0 × 10−6 g mL−1. The detection limit (3s
b) is 1 × 10−10 g mL−1 Cr and the relative standard deviation is 1.9% (5.0 × 10−8 g mL−1 of Cr(III) solution, n = 11). The method was applied to the determination of Cr(III) and total Cr in water samples and compared satisfactorily with
the official method. 相似文献
2.
Ashraf A. Mohamed 《Monatshefte für Chemie / Chemical Monthly》2001,132(8):919-928
Summary. A new selective, sensitive, and simple kinetic method is developed for the determination of trace amounts of iodide. The
method is based on the catalytic effect of iodide on the reaction of triflupromazine (TFP) with H2O2. The reaction is followed spectrophotometrically by tracing the oxidation product at 498 nm within 1 min after addition of
H2O2. The optimum reaction conditions are TFP (0.4 × 10−3
M), H2SO4 (1.0M), H3PO4 (2.0M), and H2O2 (1.6M) at 30°C. Following this procedure, iodide can be determined with a linear calibration graph up to 4.5 ng ċ cm−3 and a detection limit of 0.04 ng ċ cm−3, based on the 3 Sb criterion. The method can also be applied to the determination of iodate and periodate ions. Determination of as little as
0.2, 1.0, 2.0, and 4.0 ng ċ cm−3 of I−, IO3
-, or IO4
- in aqueous solutions gave an average recovery of 98% with relative standard deviations below 1.6% (n = 5). The method was applied to the determination of iodide in Nile river water and ground waters as well as in various food
samples after alkaline ashing treatment. The method is compared with other catalytic spectrophotometric procedures for iodide
determination.
Received January 19, 2001. Accepted (revised) March 12, 2001 相似文献
3.
Abdel-Aziz Youssef El-Sayed Ebtesam Ahmad Saad Basheer Mohamed Mohamed Ibrahime Mohamed Tarek Mohamed Zaki 《Mikrochimica acta》2000,135(1-2):19-27
Simple, rapid, sensitive and selective methods for the determination of Cr(III) and W(VI) with flavonol derivatives in the
presence of surface-active agents are proposed. In the pH ranges 3.4–4.2 and 1.9–2.5, the molar absorptivities of Cr(III)-morin-emulsifier
S (EFA) and W(VI)-morin-polyvinylpyrrolidone (PVP) systems are 1.13×105 and 2.13×104 L mol−1 cm−1 at 435 and 415 nm, respectively. The Cr(III)-quercetin-PVP and W(VI)-quercetin-cetylpyridinium bromide (CPB) systems are
formed in the pH ranges 4–4.6 and 2.2–2.8 with molar absorptivities 1.02×105 and 9.02×104 L. mol−1 cm−1 at 441 and 419 nm, respectively. The linear dynamic ranges for the determination of Cr(III) and W(VI) with morin in the presence
of EFA and PVP are 0.03–0.46 and 0.71–8.1 μg mL−1, respectively. The corresponding ranges with quercetin are 0.04–0.54 and 0.14–2.1 μg mL−1 of Cr(III) and W(VI), respectively. The r.s.d (n = 10) for the determination of 0.25 and 3.7 μg mL−1 of Cr(III) and W(VI) with morin and their detection limits are 0.88 and 0.99% and 0.016 and 0.63 μg mL−1, respectively. Using quercetin, the r.s.d (n = 10) for 0.22 and 1.2 μg mL−1 of Cr(III) and W(VI) and their detection limits are 0.92 and 0.91% and 0.015 and 0.08 μg mL−1, respectively. The critical evaluation of the proposed methods is performed by statistical analysis of the experimental data.
The proposed methods are applied to determine Cr in steel, non-ferrous alloys, wastewater and mud filtrate and to the determination
of W in steel.
Received March 8, 1999. Revision January 21, 2000. 相似文献
4.
Silica gel was prepared by the sol–gel method, modified with nanometer-sized zirconium oxide, and this material was characterized
by X-ray diffraction. A micro-column packed with silica gel modified with nanometer zirconium oxide as sorbent has been developed
for the quantitative separation and preconcentration of trace amounts of chromium(III) prior to their determination by electrothermal
atomic absorption spectrometry. Total chromium was determined after the reduction of chromium(VI) to chromium(III) by 10%
(m/v) of aqueous ascorbic acid as reducing reagent. The adsorption capacity for chromium(III) was found to be 2.36 mg g−1. The detection limit for chromium(III) was 15 ng L−1 with an enrichment factor of 100. The relative standard deviation was 3.2% (n = 7, c = 2.0 ng mL−1). 相似文献
5.
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
6.
Ashraf A. Mohamed 《Monatshefte für Chemie / Chemical Monthly》2001,56(2):919-928
A new selective, sensitive, and simple kinetic method is developed for the determination of trace amounts of iodide. The method is based on the catalytic effect of iodide on the reaction of triflupromazine (TFP) with H2O2. The reaction is followed spectrophotometrically by tracing the oxidation product at 498 nm within 1 min after addition of H2O2. The optimum reaction conditions are TFP (0.4 × 10−3 M), H2SO4 (1.0M), H3PO4 (2.0M), and H2O2 (1.6M) at 30°C. Following this procedure, iodide can be determined with a linear calibration graph up to 4.5 ng ċ cm−3 and a detection limit of 0.04 ng ċ cm−3, based on the 3 Sb criterion. The method can also be applied to the determination of iodate and periodate ions. Determination of as little as 0.2, 1.0, 2.0, and 4.0 ng ċ cm−3 of I−, IO3 -, or IO4 - in aqueous solutions gave an average recovery of 98% with relative standard deviations below 1.6% (n = 5). The method was applied to the determination of iodide in Nile river water and ground waters as well as in various food samples after alkaline ashing treatment. The method is compared with other catalytic spectrophotometric procedures for iodide determination. 相似文献
7.
Gisele B. Tonietto José M. Godoy Ana Cristina Oliveira Marcia V. de Souza 《Analytical and bioanalytical chemistry》2010,397(5):1755-1761
High-performance liquid chromatography (HPLC) coupled to an ICP-MS with an octapole reaction system (ORS) has been used to
carry out quantitative speciation of selenium (Se) and arsenic (As) in the stream waters of a refining process. The argon
dimers interfering with the 78Se and 80Se isotopes were suppressed by pressurizing the octapole chamber with 3.1 mL min−1 H2 and 0.5 mL min−1 He. Four arsenic species arsenite—As(III), arsenate (As(V)), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)—and
three inorganic Se species—selenite Se(IV), selenate Se(VI), and selenocyanate (SeCN−)—were separated in a single run by ion chromatography (IC) using gradient elution with 100 mmol L−1 NH4NO3, pH 8.5, adjusted by addition of NH3, as eluent. Repeatabilities of peak position and of peak area evaluation were better than 1% and about 3%, respectively.
Detection limits (as 3σ of the baseline noise) were 81, 56, and 75 ng L−1 for Se(IV), Se(VI), and SeCN−, respectively, and 22, 19, 25, and 16 ng L−1 for As(III), As(V), MMA, and DMA, respectively. Calibration curve R
2 values ranged between 0.996 and 0.999 for the arsenic and selenium species. Column recovery for ion chromatography was calculated
to be 97 ± 6% for combined arsenic species and 98 ± 3% for combined selenium species. Because certified reference materials
for As and Se speciation studies are still not commercially available, in order to check accuracy and precision the method
was applied to certified reference materials, BCR 714, BCR 1714, and BCR 715 and to two different refinery samples—inlet and
outlet wastewater. The method was successfully used to study the quantitative speciation of selenium and arsenic in petroleum
refinery wastewaters. 相似文献
8.
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
9.
Summary. A new selective, sensitive, and simple kinetic method is developed for the determination of trace amounts of chromium (VI). The method is based on the catalytic effect of Cr(VI) on the reaction of sodium pyrogallol-5-sulphonate (PS) with hydrogen peroxide. The reaction is followed spectrophotometrically by tracing the oxidation product at 437nm within 1min after addition of H2O2. The optimum reaction conditions are PS (1.32·10–3mol·dm–3), H2O2 (0.32mol·dm–3), HClO4 (2.6·10–3mol·dm–3) at 25°C. Following this procedure, chromium (VI) can be determined with a linear calibration graph up to 0.25ng·cm–3 and a detection limit of 0.024ng·cm–3, based on the 3 criterion. The interference effect of several species was also investigated and it was found that the most common cations and anions do not interfere with the determination. The developed procedure was successfully applied to the determination of Cr(VI) and total Cr in river waters and total Cr in herbal samples. 相似文献
10.
Zirconium (IV) was determined spectrophotometrically by reaction with quercetin as primary ligand and oxalate as secondary
ligand. Polyvinylpyrrolidone (PVP) was used as protective colloid to solubilize the formed zirconium quercetin oxalate ternary
complex. The molar absorptivity of the 1:3:1 (zirconium–quercetin–oxalate) complex is 7.31 × 104 L·mol−1 cm−1 at 430 nm with a stability constant of 8.2 × 1020 and its detection limit is 0.16 mg/L. Beer’s law is rectilinear up to 1.46 mg/L of zirconium (IV). The sensitivity index
is 1.25 ng cm−2.
The reaction of aluminium (III) with quercetin in presence of PVP as a surfactant has been studied spectrophotometrically.
The molar absorptivity of the 1:3 (aluminium–quercetin) complex is 8.09 × 104 × L·mol−1·cm−1 at 433 nm, its stability constant is 2.6 × 1013 with sensitivity index of 0.33 ng·cm−2 and its detection limit is 0.08 mg/L. The optimal conditions for the quantitative determination of zirconium and aluminium
were studied. The proposed methods are examined by statistical analysis of the experimental data. The methods are free from
interference of most cations and anions. The proposed methods have been used to determine zirconium and aluminium in industrial
waste water.
Received May 30, 2001; accepted November 2, 2001; published online July 15, 2002 相似文献
11.
A simple and selective method using ammonium pyrrolidinedithiocarbamate modified activated carbon (APDC-AC) as solid phase
extractant has been developed for speciation of As(III) in water samples. At pH 1.8–3.0, As(III) could be adsorbed quantitatively
by APDC-AC, and then eluted completely with 2.0 mL of 0.1 mol L−1 HNO3, while As(V) could almost not be retained at pH 1–7. Effects of acidity, sample flow rate, concentration of elution solution
and interfering ions on the recovery of As(III) have been systematically investigated. Under the optimal conditions, the adsorption
capacity of APDC-AC for As(III) is 7.3 mg g−1. The detection limit (3σ) of As(III) is 0.05 ng mL−1 for graphite furnace atomic absorption spectrometry (GFAAS) with enrichment factor of 50, and the relative standard deviation
(RSD) is 4.1% (n = 9, C = 5 ng mL−1). The method has been applied to the determination of trace As(III) in water, and the recoveries of As(III) are 100 ± 10%.
Correspondence: Yiwei Wu, Department of Chemistry and Environmental Engineering, Hubei Normal University, Huangshi 435002,
P.R. China 相似文献
12.
Akhmad Sabarudin Osamu Noguchi Mitsuko Oshima Keiro Higuchi Shoji Motomizu 《Mikrochimica acta》2007,159(3-4):341-348
Chitosan resin functionalized with 3,4-dihydroxy benzoic acid (CCTS-DHBA resin) was used as a packing material for flow injection
(FI) on-line mini-column preconcentration in combination with inductively coupled plasma-atomic emission spectrometry (ICP-AES)
for the determination of trace elements such as silver, bismuth, copper, gallium, indium, molybdenum, nickel, uranium, and
vanadium in environmental waters. A 5-mL aliquot of sample (pH 5.5) was introduced to the minicolumn for the adsorption/preconcentration
of the metal ions, and the collected analytes on the mini-column were eluted with 2 M HNO3, and the eluates was subsequently transported via direct injection to the nebulizer of ICP-AES for quantification. The parameters
affecting on the sensitivity, such as sample pH, sample flow rate, eluent concentration, and eluent flow rate, were carefully
examined. Alkali and alkaline earth metal ions commonly existing in river water and seawater did not affect the analysis of
metals. Under the optimum conditions, the method allowed the determination of metal ions with detection limits of 0.08 ng mL−1 (Ag), 0.9 ng mL−1 (Bi), 0.07 ng mL−1 (Cu), 0.9 ng mL−1 (Ga), 0.9 ng mL−1 (In), 0.08 ng mL−1 (Mo), 0.09 ng mL−1 (Ni), 0.9 ng mL−1 (U), and 0.08 ng mL−1 (V). By using 5 mL of sample solution, the enrichment factor and collection efficiency were 8–12 fold and 96–102%, respectively,
whereas the sample throughput was 7 samples/hour. The method was validated by determining metal ions in certified reference
material of river water (SLRS-4) and nearshore seawater (CASS-4), and its applicability was further demonstrated to river
water and seawater samples. 相似文献
13.
Summary. A new simple, rapid, sensitive, and selective method is proposed for the microdetermination of mercury. Mercury(II) forms
insoluble complexes with 2,3-dichloro-6-(2-hydroxy-3,5-dinitrophenylazo)-quinoxaline (1), 2,3-dichloro-6-(5-amino-3-carboxy-2-hydroxy-phenylazo)-quinoxaline (2), 2,3-dichloro-6-(2,7-dihydroxynaphth-1-ylazo)-quinoxaline (3), and 2,3-dichloro-6-(3-carboxy-2-hydroxy-naphth-1-ylazo)-quinoxaline (4) in aqueous acidic medium; the complexes can be made soluble by the action of an anionic surfactant. The solution of the
pink coloured compounds is stable for at least 24 h. Beer’s law is obeyed over the concentration range from 0.1 to 2.8 μg · cm−3 of mercury. For a more accurate analysis, Ringbom optimum concentration ranges were found to be 0.25–2.5 μg · cm−3. The molar absorpitivity, Sandell sensitivity, and relative standard deviations were also calculated. A slight interference from Pd2+ and Cd2+ is exhibited by the first three ligands, whereas the last one is only negligibly affected by these metal ions. Strong interference
from Ag(I) is evident for all ligands, whereas alkali, alkaline earth, and other transition metals tested posed negligible
interference. 15 μg · cm−3 of Cd2+ and Pd2+ or 10 μg · cm−3 of Ag+ can be tolerated if 1.0 mg of potassium bromide and 2.0 mg of citrate as masking agents are added for the determination of
1.5 μg · cm−3 of mercury(II). The method was applied to the determination of methyl- and ethylmercury chloride and the analysis of environmental
water samples.
Received August 7, 2000. Accepted (revised) October 18, 2000 相似文献
14.
Roseli M. de Souza Bárbara M. Mathias Ieda S. Scarminio Carmem Lúcia P. da Silveira Ricardo Q. Aucélio 《Mikrochimica acta》2006,153(3-4):219-225
Inductively coupled plasma optical emission spectrometry (ICP OES) was used to determine Mo, Cr, V and Ti, in diesel and in
used fuel oil. Samples were introduced into the ICP as emulsions to reduce interferences and allow the use of inorganic standards
for quantification. A comparative study between one Triton X-100 emulsion and one detergentless emulsion was made. A 23 factorial design was applied to elucidate and establish the relationship between three experimental variables: presence of
HNO3, amount of diesel fuel oil (between 5 and 25%) and the presence or O2 into the Ar plasma gas flow rate. Results indicated that best performance were achieved using 10% sample (w/w) together with
concentrated HNO3 (0.5 mL) and using O2 as auxiliary gas (0.047 L min−1). The use of O2 minimized both carbon deposits at the injector tip and plasma background. The addition of HNO3 resulted in good correlation between inorganic standards used for calibration, and metallo-organic standards used for sample
enrichment. Analyte enriched diesel and SRM 1634b were analyzed using the optimized conditions. Recoveries from 90.1 to 106.5%
were achieved, with better results for detergent emulsions which enabled limits of detection at the ng g−1 range for Mo, Cr, V and Ti and at smaller background. 相似文献
15.
Dhanpat Rai Dean A. Moore Nancy J. Hess Kevin M. Rosso Linfeng Rao Steve M. Heald 《Journal of solution chemistry》2007,36(10):1261-1285
Chromium(III)-carbonate reactions are expected to be important in managing high-level radioactive wastes. Extensive studies
on the solubility of amorphous Cr(III) hydroxide solid in a wide range of pH (3–13) at two different fixed partial pressures
of CO2(g) (0.003 or 0.03 atm.), and as functions of K2CO3 concentrations (0.01 to 5.8 mol⋅kg−1) in the presence of 0.01 mol⋅dm−3 KOH and KHCO3 concentrations (0.001 to 0.826 mol⋅kg−1) at room temperature (22±2 °C) were carried out to obtain reliable thermodynamic data for important Cr(III)-carbonate reactions.
A combination of techniques (XRD, XANES, EXAFS, UV-Vis-NIR spectroscopy, thermodynamic analyses of solubility data, and quantum
mechanical calculations) was used to characterize the solid and aqueous species. The Pitzer ion-interaction approach was used
to interpret the solubility data. Only two aqueous species [Cr(OH)(CO3)22− and Cr(OH)4CO33−] are required to explain Cr(III)-carbonate reactions in a wide range of pH, CO2(g) partial pressures, and bicarbonate and carbonate concentrations. Calculations based on density functional theory support
the existence of these species. The log 10
K° values of reactions involving these species [{Cr(OH)3(am) + 2CO2(g)⇌Cr(OH)(CO3)22−+2H+} and {Cr(OH)3(am) + OH−+CO32−
⇌Cr(OH)4CO33−}] were found to be −(19.07±0.41) and −(4.19±0.19), respectively. No other data on any Cr(III)-carbonato complexes are available
for comparisons. 相似文献
16.
Krzysztof Miecznikowski James A. Cox Adam Lewera Pawel J. Kulesza 《Journal of Solid State Electrochemistry》2000,4(4):199-204
We describe a sol-gel approach by which iron hexacyanoferrate is immobilized in silica in a manner suited to investigation
by electrochemistry in the absence of a contacting liquid phase. Such physicochemical parameters as concentration of redox
sites (C
o) and apparent (effective) diffusion coefficient (D
app) are estimated by performing cyclic voltammetric and potential step experiments in two time regimes, which are characterized
by linear and spherical diffusional patterns, respectively. Values of D
app and C
o thereby obtained are 2.0 × 10−6 cm2 s−1 and 1.4 × 10−2 mol dm−3. The D
app value is larger than expected for a typical solid redox-conducting material. Analogous measurements done in iron(III) hexacyanoferrate(III)
solutions of comparable concentrations, 1.0 × 10−2 and 5.0 × 10−3 mol dm−3, yield D
app on the level of 5–6 × 10−6 cm2 s−1. Thus, the dynamics of charge propagation in this sol-gel material is almost as high as in the liquid phase. The residual
water in the silica, along with the pore structure, are important to the overall mechanism of charge transport, which apparently
is limited by physical diffusion rather than electron self-exchange. Under conditions of a solid state voltammetric experiment
which utilizes an ultramicroelectrode, encapsulated iron hexacyanoferrate redox centers seem to be in the dispersed colloidal
state rather than in a form of the rigid polymeric film.
Received: 8 April 1999 / Accepted: 13 August 1999 相似文献
17.
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
18.
Samuel Melaku Ilse Gelaude Frank Vanhaecke Luc Moens Richard Dams 《Mikrochimica acta》2003,142(1-2):7-12
Microwave digestion reduction-aeration and pyrolysis combined with cold vapour atomic absorption and cold vapour atomic fluorescence
are compared for the determination of total mercury in several biological and environmental matrices. The biological samples
were digested in a mixture of HNO3/H2O2, the environmental samples in a mixture of HNO3/HClO4. After reduction with SnCl2, the mercury was collected by two-stage gold amalgamation. After microwave digestion reduction-aeration, detection limits
of 1.4 ng g−1 and 0.6 ng g−1 were obtained for cold vapour atomic absorption spectrometry (CVAAS) and cold vapour atomic fluorescence spectrometry (CVAFS),
respectively, for 250 mg of environmental samples. For biological samples (500 mg) the detection limits were 0.7 ng g−1 (CVAAS) and 0.4 ng g−1 (CVAFS). After pyrolysis, detection limits of 3.5 ng g−1 and 1.6 ng g−1 for CVAAS and CVAFS, respectively, were obtained for a 10 mg sample. Pyrolysis can only be applied when the organic content
of the sample is not too high. Accurate results were obtained for 8 certified reference materials of both environmental and
biological origin. In addition, a real sludge sample was analysed.
Author for correspondence. E-mail: richard.dams@rug.ac.be
Received September 18, 2002; accepted December 3, 2002
Published online May 5, 2003 相似文献
19.
Raúl A. Sánchez-Moreno M. Jesús Gismera M. Teresa Sevilla Jesús R. Procopio 《Analytical and bioanalytical chemistry》2010,397(1):331-338
A disposable screen-printed electrode was designed and evaluated for direct detection of chromium(VI) in batch and flow analysis.
The carbon screen-printed electrode was modified with a graphite–epoxy composite. The optimal graphite–epoxy matrix contains
37.5% graphite powder, 12.5% diphenylcarbohydrazide, a selective compound for chromium(VI), and 50% epoxy resin. The principal
analytical parameters of the potentiometric response in batch and flow analysis were optimized and calculated. The screen-printed
sensor exhibits a response time of 20 ± 1 s. In flow analysis, the analytical frequency of sampling is 70 injections per hour
using 0.1 M NaNO3 solution at pH 3 as the carrier, a flow rate of 2.5 mL·min−1, and an injection sample volume of 0.50 mL. The sensor shows potentiometric responses that are very selective for chromium(VI)
ions and optimal detection limits in both static mode (2.1 × 10−7 M) and online analysis (9.4 × 10−7 M). The disposable potentiometric sensor was employed to determine toxicity levels of chromium(VI) in mineral, tap, and river
waters by flow-injection potentiometry and batch potentiometry. Chromium(VI) determination was also carried out with successful
results in leachates from municipal solid waste landfills. 相似文献
20.
Crosslinked chitosan-bound FeC nanoparticles (CCBFeCNP) were prepared, and the adsorptive behavior of Cr(III) and Cr(VI) on
CCBFeCNP were assessed. At pH 6.0–10.0, CCBFeCNP is selective towards Cr(III) but hardly selective towards Cr(VI). The retained
Cr(III) is subsequently eluted with 0.5 mol L−1 HCl. Total chromium is determined after reduction of Cr(VI) to Cr(III) by ascorbic acid. A new method of flow injection using
a micro-column packed with CCBFeCNP as solid phase extractant has been developed for speciation of Cr(III) and Cr(VI) in water
samples, followed by flame atomic absorption spectrometry. The effects of pH, sample flow rate and volume, elution solution
and interfering ions on the recoveries of Cr(III) were systematically investigated. Under optimum conditions, the adsorption
capacity of CCBFeCNP for Cr(III) is 10.5 mg g−1 at pH 7.5. The procedure presented was applied to chromium speciation in water samples, and the results were satisfactory. 相似文献