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1.
V. N. Losev S. I. Metelitsa E. V. Elsuf’ev A. K. Trofimchuk 《Journal of Analytical Chemistry》2009,64(9):903-909
Silica gel chemically modified with N-(1,3,4-thiodiazole-2-thiol)-N′-propylurea extracted gold(III) from solutions in the range of 6 M HCl-pH 8 and silver(I) from nitric acid solutions in the
range of 6 M HNO3-pH 8 and 1–2 M HCl at 20°C with 99.0–99.9% recovery and a sorption equilibration time of 5 min. Platinum(II) was quantitatively
extracted at room temperature from solutions in the range of 4 M HCl-pH 8; the sorption equilibration time was 20 min. For
the quantitative extraction of platinum(IV), it should be reduced to platinum(II). The intense yellowish orange luminescence
(λmax (Au) = 575 nm, λmax (Ag) = 550 nm, and λmax(Pt) = 620 nm) of surface complexes at 77 K under UV irradiation was used in the development of procedures for the low-temperature
sorption-luminescence determination of gold, silver, and platinum. The detection limits were 0.15 (Au), 0.1 (Ag), and 0.05
μg (Pt) per 0.1 g sorbent. The calibration function was linear to 50 (Au, Ag) or 80 μg (Pt) per 0.1 g sorbent. The relative
standard deviation in the determination of more than 5 μg of a metal was no higher than 6%. The sorption-luminescence determination
procedures were tested in the determination of gold in gold-containing concentrates and their processing products and platinum
in alumina-platinum catalysts. 相似文献
2.
Galia Gentscheva Penka Tzvetkova Paunka Vassileva Lako Lakov Ognyan Peshev Elisaveta Ivanova 《Mikrochimica acta》2006,156(3-4):303-306
The sorption behavior of a newly synthesized silica gel sorbent with thioetheric sites (STS) towards microgram levels of Au(III),
Pt(IV) and Pd(II) was studied. Au(III) is quantitatively (>95%) sorbed in the pH region of 1–9. The sorption of Pt(IV) starts
at pH 1 and does not exceed 25% in the entire pH region examined. The sorption of Pd(II) starts at pH 7 and reaches 80% at
pH 9. The sorption of Au(III) on STS at pH 1 is not affected by milligram amounts of Ni(II), Zn(II), Fe(III), Cu(II), Pb(II),
Cd(II) or Co(II). Au(III) is quantitatively eluted with a 5% aqueous solution of thiourea. The adsorption capacity of STS
towards Au(III) is 195 mg g−1. The detection limit (DL) of Au(III) (3σ, n = 9) is 25 ng mL−1. The RSD at a level of 10 × DL is about 2%. Solid-phase extraction of trace amounts of Au(III) on the STS sorbent, followed
by its flame AAS determination in the eluate was applied to the determination of gold in geological samples. The results obtained
for the gold content in the samples were in good agreement with those of the ICP-AES analysis. 相似文献
3.
V. G. Amelin N. S. Aleshin O. I. Abramenkova Yu. N. Nikolaev I. A. Lomonosov 《Journal of Analytical Chemistry》2011,66(8):709-713
A fluorimeter is developed, which provides sample pretreatment, preconcentration of analytes from natural waters on the surface
of indicator cellulose matrices, and the simultaneous measurement of their fluorescence. The device employs a L-711UVC ultraviolet
light diode and a Digital color sensor S9706 photodiode, which registers simultaneously in the red (615 nm), green (540 nm),
and blue (465 nm) spectrum regions. The opportunities of the application of this fluorimeter have been shown by an example
of determination of 1–100 μg/L Al(III) and 0.1–10 μg/L Be(II) and Ga(III). 相似文献
4.
M. Ya. Kamentsev Ya. S. Kamentsev L. N. Moskvin N. M. Yakimova 《Journal of Analytical Chemistry》2011,66(2):212-214
A new version of online preconcentration employing the pH-stacking mechanism has been proposed; it has been implemented by
the example of a procedure for the capillary electrophoretic determination of trace zinc(II) and cadmium(II) with photometric
detection in the visible spectrum region as complexes with Xylenol Orange. The analytical range is 2–400 μg/L for zinc(II)
and 1–500 μg/L for cadmium(II). 相似文献
5.
E. Morosanova A. Velikorodny Y. Zolotov 《Fresenius' Journal of Analytical Chemistry》1998,361(3):305-308
Two approaches to immobilize complex-forming analytical reagents (PAN, PAR, Xylenol orange, Brombenzothiazo, Crystal violet,
Cadion, and Sulfochlorophenolazorhodanine) for the preparation of new sorbents and indicator powders are suggested: on-line
coating of reversed-phase silica gel by reagents or doping of porous sol-gel silica with reagents. The retention of Ag, Cd,
Cu(II), Co(II), Fe(III), Mn(II), Ni, Pb, and Zn on the sorbents developed was investigated. Quantitative sorption and desorption
conditions were optimized. Procedures for the determination of Cd, Cu(II), Fe(III), Pb, and Zn with flame atomic absorption,
spectrophotometric, and diffusion scattering spectrometric detection were elaborated. Detection limits for Cd, Cu(II), Fe(III),
Pb, and Zn were 3 μg/L, 6 μg/L, 5 μg/L, 40 μg/L, and 1 μg/L, respectively. The procedures were used for the analysis of various
real samples, e.g., natural and waste waters, and food.
Received: 17 July 1997 / Revised: 20 January 1998 / Accepted: 5 February 1998 相似文献
6.
Summary A reversed-phase ion-pair chromatographic (RPIPC) method withN,N,N′, N′-ethylenediaminetetrakis(methylenephosphonic acid) (EDTMP) as coordinating agent has been developed for simultaneous separation
and detection of Cu(II), Fe(III), and Pb(II) ions. Response is linearly dependent on amount of sample over the range 9.52–50.8
μg mL−1 for Cu(II), 8.31–41.8 μg mL−1 for Fe(III), and 37.3–51.8 μg mL−1 for Pb(II). The method has been applied successfully to an artificial mixed-ore sample. 相似文献
7.
Summary Capillary GC of metal chelates of diethyl dithiocarbamate (DDTC) was examined on a methylsilicone DB-1 column, (25 meter,
0.2 mm. i.d) with a film thickness of 0.25 μm. Elution was carried out at the initial column temperature of 180°C and programmed
at 5°C min−1 to 260°C. Detection was by FID or ECD. Symmetrical peaks with base line separation were obtained with the metal chelates
of copper(II), nickel(II), cobalt(III), manganese(II) and chromium(III). The ECD gave better sensitivity than the FID with
a linear calibration range of 5–50 μg mL−1 and detection limits 2.0–6.0 μg mL−1, corresponding to 111–333 pg of metal ion reaching the detector. The method was applied to the determination of metal ions
in water and pharmaceutical preparations with a coefficient of variation (CV) within 4.0%. When compared with a standard flame
AAS method the results revealed no significant difference. 相似文献
8.
This paper reports silica gel loaded with p-tert-butylcalix[8]arene as a new solid phase extractor for determination of trace level of uranium. Effective extraction conditions
were optimized in column methods prior to determination by spectrophotometry using arsenazo(III). The results showed that
U(VI) ions can be sorbed at pH 6 in a mini-column and quantitative recovery of U(VI) (>95–98%) was achieved by stripping 0.4 mol L−1 HCl. The sorption capacity of the functionalized sorbent is 0.072 mmol uranium(VI) g−1 modified silica gel. The relative standard deviation and detection limit were 1.2% (n = 10) for 1 μg uranium(VI) mL−1 solution and 0.038 μg L−1, respectively. The method was employed to the preconcentration of U(VI) ions from spiked ground water samples. 相似文献
9.
A simple and fast flow injection fluorescence quenching method for the determination of iron in water has been developed.
Fluorimetric determination is based on the measurement of the quenching effect of iron on salicylic acid fluorescence. An
emission peak of salicylic acid in aqueous solution occurs at 409 nm with excitation at 299 nm. The carrier solution used
was 2 × 10−6 mol L−1 salicylic acid in 0.1 mol L−1 NH4+/NH3 buffer solution at pH 8.5. Linear calibration was obtained for 5–100 μg L−1 iron(III) and the relative standard deviation was 1.25 % (n = 5) for a 20 μL injection volume iron(III). The limit of detection
was 0.3 μg L−1 and the sampling rate was 60 h−1. The effect of interferences from various metals and anions commonly present in water was also studied. The method was successfully
applied to the determination of low levels of iron in real samples (river, sea, and spring waters). 相似文献
10.
Various silica gel materials were chemically modified with imidazole, diaza-18-crown-6 (DA18C6) and dibenzod-18-crown-6 (DB18C6). The degree of functionalization of the covalently attached molecule was calculated from C, H, N analysis and ranged between 0.270 and 0.552 mmol/g (for sorbents with imidazole) and between 0.043 and 0.062 mmol/g (for sorbents with DA18C6 and DB18C6). The degree of functionalization depends on the reflux time and silica gel matrix used. Experimental sorption capacity ranged between 0.038 and 0.228 mmol/g (for sorbents with imidazole) and between 0.019 and 0.050 mmol/g (for sorbents with DA18C6 and DB18C6). Synthesized hexagonal mesoporous silica matrix MCM-41 with uniform pore diameter <40 Å was used too. Change of pore diameters of silica gel support to larger pores should have a positive influence on access of cobalt ion to sorption centers to increase of sorption capacity of sorbents. The sorption kinetics of cobalt and the influence of cobalt concentration, pH of various kinds of silica gel matrix with immobilized imidazole group in static conditions on sorption were measured. The sorption of cobalt in various conditions (pH, contact time of phases) with constant liquid-solid ratio (V/m = 50 ml/g) was studied. The distribution coefficients ranged between 200 and 50 000 ml/g (for imidazole), 85 and 120 ml/g (for DB18C6) and between 230 and 500 ml/g (for DA18C6) according to silica gel matrix used and according to the method of sorbent preparation. pH plays important role in the sorption of cobalt on prepared sorbents with immobilized crown ethers due to protonization of crown ethers. Protons significantly competes to sorption of cobalt in acidic solutions. The influence of presence of other heavy or toxic metals (Hg(II), Cd(II), Mn(II), Zn(II), Cu(II), Fe(III), Cr(III), Al(III) and the influence of sodium and potassium on sorption Co(II) from aqueous solutions was investigated. Sorption of cobalt decreases in order Hg > Cu > Cd > Zn, Fe > Mn > Al, Cr. The presence of sodium and potassium ions at concentration 0.05 mol/l significantly influences on the sorption of cobalt with sorbent with immobilized DB18C6 functional group. 相似文献
11.
This paper describes a novel method to determine methimazole by spectrophotometry using a potassium ferricyanide-Fe(III) reaction.
The study indicates that at pH 4.0 Fe(III) is reduced to Fe(II) by methimazole and in situ formed Fe(II) reacts with potassium
ferricyanide to give soluble Prussian Blue which is characterized by means of XRD analysis. The absorbance of Prussian Blue
is measured at the absorption maximum of 735 nm, and the amount of methimazole can be determined based on this absorbance.
Beer’s law is obeyed in the range of methimazole concentrations of 0.02–6.00 μg/mL. The equation of the linear regression
is A = −0.0058 + 0.49988c (μg/mL), with a correlation coefficient of 0.9998 and RSD of 0.80%. The detection limit (3σ/k) is 0.015 μg/mL, and the apparent
molar absorption coefficient of indirect determination of methimazole is 5.7 ± 104 L/mol cm. This method has been successfully applied to the determination of methimazole in pharmaceutical, serum and urine
samples, and average recoveries are in the range of 98.6–102.4%. Analytical results obtained with this novel method are satisfactory. 相似文献
12.
A. V. Pestov S. Yu. Bratskaya A. B. Slobodyuk V. A. Avramenko Yu. G. Yatluk 《Russian Chemical Bulletin》2010,59(7):1303-1306
Thiocarbamoyl chitosan (TCC) was synthesized by grafting thiourea on chitosan backbone in eutectic composition of ammonium
thiocyanate—thiourea. Insoluble products with the amno group functionalization degree of 0.3–1.1 can be prepared by varying
the conditions of polymer-analogous (synthesis in a gel) transformation. Structure of the synthesized chitosan derivatives
was characterized by elemental analysis, diffuse reflectance infrared spectroscopy, and the solid state 13C NMR. Study of sorption properties of TCC shows high sorption capacity and selectivity for the ions of gold(III), platinum(IV),
and palladium(II) as evidenced by results obtained at pH 2 in the presence of 100–1000-fold excess of iron(III), copper(II),
zinc(II), and nickel(II). Sorption capacity of TCC for all ions increases with the increase in the degree of substitution
and changes in the series: AuIII > PdII > PtIV. 相似文献
13.
M. A. Campanero A. M. Zamarreño M. Simón M. C. Dios J. R. Azanza 《Chromatographia》1997,46(7-8):374-380
Summary A simple and rapid liquid chromatographic method has been developed for the determination of therapeutic levels of piperacillin
(I) and ceftazidime (II) in human plasma. Plasma and p-propionamidophenol (internal standard) were precipitated with methanol
(I) or 20% trichloroacetic acid (II). The supernatant was analysed on a 5 μm Spherisorb ODS C18 column with acetonitrile-0.05 M phosphate buffer pH 3.8 as mobile phase and ultraviolet detection at 254 nm. The calibration
graph was linear from 10 to 250 μg mL−1, for (I), and from 5 to 200 μg mL−1 for (II). Intra and inter-day CV did no exceed 2.29% for (I), and were 10.76–11.13%–2.00–5.62 for (II) at concentrations
of 10 μg mL−1 and 250 μg mL−1. 相似文献
14.
Jaw-Cherng Hsu Chin-Hung Chang C.-Y. Liu 《Analytical and bioanalytical chemistry》1998,362(6):514-521
A silica based sorbent with an anion complexone polymer coating, [24]ane-N6 macrocycle, was prepared. The chelation properties of this material were investigated by elemental analysis, infrared spectra
and Voige’s method. The polymer-coated silica column (25– 40 μm, 100 × 4.6 mm i.d.) was employed for trace metal analyses.
Oxalic acid, malonic acid, succinic acid, citric acid, phthalic acid and acetic acid were used as mobile phases. Their retention
characteristics were elucidated. Oxalic acid was found to be the most effective eluent. With a mobile phase consisting of
oxalic acid (25 mM) and sodium nitrate (25 mM) at pH 4.2, the separation of copper(II), cadmium(II), cobalt(II) and zinc(II)
in sea water could be achieved. The identification of metal ions was performed at 510 nm using 4(2-pyridylazo)resorcinol (1
× 10–4 M) as post column reagent. The limits of detection were 5 × 10–7 M, 1 × 10–5 M, 3 × 10–5 M and 2 × 10–6 M for copper(II), cadmium(II), cobalt(II) and zinc(II) based on three times the standard deviation of the response for the
lowest concentration (n = 5) in the chromatogram with a sample volume of 50 μL. For evaluation of data reliability, oyster
tissue (NIST SRM 1566 a) was studied with the proposed system.
Received: 9 February 1998 / Revised: 15 May 1998 / Accepted: 16 June 1998 相似文献
15.
A simple, rapid, accurate and sensitive spectrophotometric method for the microdetermination of some pharmaceutically important
aminoquinoline antimalarials, namely amodiaquine dihydrochloride (I), chloroquine phosphate (II) and primaquine phosphate
(III) is described. The method is based on the interaction of these drugs with calmagite indicator to give highly coloured
ion-pair complexes which exhibit maximum absorption at 663, 665 and 666 nm, respectively, Beer’s law is obeyed in the concentration
ranges 1.0–25.0, 1.0–28.0 and 1.0–33.0 μg/ml for the drugs I, II and III, respectively. For more accurate analysis, the Ringbom
optimum concentration ranges are 2.5–22.5, 2.0–26.0 and 3.0–30.0 μg/ml, respectively. The apparent molar absorptivities were
calculated. Statistical treatment of the experimental results indicates that the method is sufficiently accurate and precise.
The accuracy of the method is indicated by the recovery (99.8±1.4%) and the precision by the relative standard deviation (>1.5%).
The proposed method has been applied to the determination of these drugs in certain formulations, with results that compared
favourably with those obtained by the official methods.
Received November 2, 1998. Revision February 29, 2000. 相似文献
16.
Halil İbrahim Ulusoy Ramazan Gürkan Öznur Yılmaz Mehmet Akçay 《Journal of Analytical Chemistry》2012,67(2):131-139
A sensitive and selective method has been developed for the determination of chromium in water samples based on using cloud
point extraction (CPE) preconcentration and determination by flame atomic absorption spectrometry (FAAS). The method is based on the complexation of Cr(III) ions with Brilliant Cresyl Blue (BCB) in the presence of non-ionic surfactant Triton X-114. Under the optimum conditions, the preconcentration of 50 mL of water
sample in the presence of 0.5 g/L Triton X-114 and 1.2 × 10−5 M BCB permitted the detection of 0.42 μg/L chromium(III). The calibration graph was linear in the range of 1.5–70 μg/L, and
the recovery of more than 99% was achieved. The proposed method was used in FAAS determination of Cr(III) in water samples
and certified water samples. In addition, the developed CPE-FAAS method was also used for speciation of the inorganic chromium
species after reduction of Cr(VI) to Cr(III) using a thiosulphate solution of 120 mg/L in the presence of Hg(II) ion as a
stabilizer. 相似文献
17.
A continuous flow atomic absorption spectrometric system was used to develop an efficient on-line preconcentration-elution
procedure for the determination of iodide traces. Chromium (VI) is introduced into the flow system and is reduced to chromium
(III) in acid medium proportionally to the iodide present in the sample. The Cr(III) reduced by iodide is retained on a minicolumn
packed with a poly(aminophosphonic acid) chelating resin, while unreduced Cr(VI) is not retained. Reduced Cr(III) is preconcentrated
by passing the sample containing iodide through the system during 3 min, and is then eluted with 0.5 mol L–1 hydrochloric acid and determined by flame atomic absorption spectrometry (FAAS). The detection limit (3σ) obtained is 2.5
μg L–1. Other ions typically present in waters do not interfere. The proposed method allows the determination of iodide in the range
6–220 μg L–1 with a relative standard deviation of 2.7% at a rate of 17 samples h–1. The method has been applied to the determination of iodide in tap and sea waters.
Received: 16 September 1999 / Revised: 15 November 1999 / Accepted: 19 November 1999 相似文献
18.
Sorption of copper on filter-paper with chemically attached hexamethylenediamino-groups (HMDA-filter) allows to obtain the
sorbent (Cu/HMDA-filter) stable in respect to desorption of copper. A nitrogen-containing herbicide imazapyr (imaz) is retained on Cu/HMDA-filters at pH 5.5–7.0 forming a relatively stable complex. Imazapyr is determined directly on the
sorbent by its activating effect in the oxidation of hydroquinone with H2O2 catalyzed by Cu(II) with the formation of a product absorbing at 490 nm. The copper ions serve both to preconcentrate imazapyr
and to catalyze the indicator reaction. The use of 1-μL sample aliquots pipetted onto the Cu/HMDA-filters allows to determine
1 × 10−3–0.03 μmol of imazapyr, whereas preconcentration of the analyte by pumping of its solution through the same sorbent expands
the linear range to 1 × 10−4–1 × 10−1 μmol of imazapyr. When the indicator reaction is carried out in solution, the range of activating action of imazapyr is narrower
(0.06–0.1 μmol a for a solution volume of 10 mL). The determination is selective: 5–100-fold amounts of amines, aminoacids,
carboxylic acid derivatives and other model compounds do not interfere. Soil extracts and carrot juice samples spiked with
imazapyr have been analyzed.
Received January 10, 2000. Revision July 28, 2000. 相似文献
19.
Summary HPLC determination of pheophytinatonicke(II) (Pheo-Ni) prepared by the replacement of magnesium(II) in chlorophyll with nicke(II)
is described. The good separation of PheoNi was obtained by using chemically bonded C18 as the stationary phase and acetone-methanol (50∶50, vol/vol) as the mobile phase. Conventional spectrophotometric method
was also used for the determination of PheoNi. For the synthetic samples prepared by mixing (pheophytinato a) nicke(II) [(Pheo-a)
Ni] and (pheophytinato b) nicke(II) [(Pheo-b) Ni], analytical values obtained by the spectrophotometric method were very high
compared to those obtained by HPLC. In the proposed HPLC method, (Pheo-a) Ni and (Pheo-b). Ni could be determined in the concentration
range of 0.028–30μg/ml and 0.038–30μg/ml with relative standard deviations (n=10) of 3.1% and 0.8%, respectively. 相似文献
20.
Elif Ant Bursali Melek Merdivan Muruvvet Yurdakoc 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):471-476
Olive cake as low-cost abundantly available sorbent has been characterized by N2 at 77 K adsorption, porosity analysis, elemental analysis and IR spectra and has been used for preconcentrating of uranium(VI)
and thorium(IV) ions prior to their determination spectrophotometrically. The optimum pH values for quantitative sorption
of U(VI) and Th(IV) are 4–7 and 3–7, respectively. The enrichment factor for the preconcentration of U(VI) and Th(IV) were
found to be 125 and 75 in the given order. The sorption capacity of olive cake is in the range of 2,260–15,000 μg g−1 for Th(IV) and in the range of 1,090–17,000 μg g−1 for U(VI) at pH 3–7. The sorbent exhibits good reusability and the uptake and stripping of the studied ions were fairly rapid.
The elution of U(VI) and Th(IV) was performed with 0.3–1 M HCl/1–2 M HNO3 and 0.3–0.8 M HCl/1 M HNO3, respectively. The precision of the method was 1.8 RSD% for U(VI) and 2.5 RSD% for Th(IV) in a concentration of 1.00 μg mL−1 for 10 replicate analysis. The influence of some electrolytes and cations as interferents was discussed. Separation of U(VI)
and Th(IV) from other metal ions in synthetic solution was achieved. 相似文献