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1.
Scandium can be extracted from 5.0 × 10−2 mol/1 sodium salicylate solution, adjusted to pH 4.0–5.0 with 0.5% triphenylphosphine oxide dissolved in toluene as an extractant.
After stripping from the organic phase with 0.5 mol/1 HCl it can be subsequently determined spectrophotometrically with Alizarin
Red S. The method permits a separation of Sc(III) from Ti(IV), V(V), Cr(VI), Fe(III), Y(III), La(III), Ce(III), Nd(III) and
Sm(III) in synthetic mixtures. The method is fast, simple and selective. 相似文献
2.
A spectrophotometric method for the selective determination of antimony (III) and (V) in antileishmanial drugs is described.
The procedure is based on the reaction of Sb(III) with bromopyrogallol red (BPR) in neutral solution. As a consequence of
the Sb-BPR complex formed, the absorbance of BPR, at 560 nm, decreases proportionally to the amount of Sb(III) in the analyte
solution. The calculated apparent molar absorptivity and determination limits are 3.67 × 104 L · cm–1 · mol–1 and 1.65 × 10–6 mol/L, respectively. Sb(V) is determined after reduction to Sb(III) by iodide. The Sb(V) content determined in ten samples
of Glucantime varied from 75.40 ± 0.97 to 94.47 ± 1.0 mg/mL. Sb(III) was detected in all samples analyzed, and mean values
ranged from 5.19 ± 0.16 to 10.52 ± 0.15 mg/mL. The method is suitable for the routine quality control of pharmaceutical formulations.
Received: 26 July 1996 / Revised: 17 October 1996 / Accepted: 11 December 1996 相似文献
3.
A square wave voltammetric method whith a static mercury drop electrode (SMDE) was developed for the quantitative determination
of iron (III) in Zn-Fe alloy galvanic baths. Real alloy bath samples were analyzed by the standard addition method and recovery
tests were carried out. 0.50 mol L–1 sodium citrate (pH 6.0) or 0.20 mol L–1 oxalic acid (pH 4.0) were applied as supporting electrolytes resulting in both cases in a peak potential of about –0.20 V
vs. Ag|AgCl (saturated KCl). The iron (III) concentration in the alloy bath was 9.0 × 10–4 mol L–1. A good correlation (r = 0.9999) was achieved between the iron (III) concentration and the peak current in the electrolytes
studied, with linear response ranges from 1.0 × 10–6 to 1.2 × 10–4 mol L–1. Interference levels for some metals such as copper (II), lead (II), chromium (III) and manganese (II) that can hinder the
Zn-Fe alloy deposition were evaluated; only copper (II) interferes seriously.
Received: 4 April 2000 / Revised: 19 June 2000 / Accepted: 22 June 2000 相似文献
4.
H. Seco-Lago J. Pérez-Iglesias J. M. Fernández-Solís J. M. Castro-Romero V. González-Rodríguez 《Analytical and bioanalytical chemistry》1997,357(4):464-466
The application of derivative spectrophotometry to the simultaneous determination of chromium (III) and copper (II) with
MEDTA is described. The procedure is suitable for concentrations of 0.40–2.60 mg ml–1 of chromium (III) and 0.15–0.60 mg ml–1 of copper (II). The main interferences, both anionic and cationic, are easily eliminated. The method was applied to different
aqueous matrices. It was compared with an atomic absorption method and good results were obtained.
Received: 12 June 1996 / Revised: 30 July 1996 / Accepted: 2 August 1996 相似文献
5.
An automated procedure for correcting the interference due to mixing the reagents in the determination of ATP by a bioluminescent
technique is described. The measurements were performed by an in-house interfaced PC photometer. An automated procedure based
on a robust regression method and outliers detection was applied to exclude the time of the mixing of the reagents from the
global time of reaction. In fact the mixing of the reagents is responsible of the poor analytical precision (RSD%>25) and
low sensitivity (limit of detection≈2×10-8 mol/l). By this procedure, the precision (RSD%<7) and sensitivity (limit of detection≈8×10-10 mol/l) were improved. The method was applied to the determination of ATP in marine sediments and good recovery within 90–108%
was obtained. For non-polluted samples the measurement can be carried out by direct comparison with standard solutions. The
standard addition procedure is recommended for polluted samples.
Received: 25 April 1996/Revised: 28 June 1996/Accepted: 3 July 1996 相似文献
6.
M. Mecozzi Marina Amici Giovanni Visco 《Fresenius' Journal of Analytical Chemistry》1997,357(6):747-751
An automated procedure for correcting the interference due to mixing the reagents in the determination of ATP by a bioluminescent
technique is described. The measurements were performed by an in-house interfaced PC photometer. An automated procedure based
on a robust regression method and outliers detection was applied to exclude the time of the mixing of the reagents from the
global time of reaction. In fact the mixing of the reagents is responsible of the poor analytical precision (RSD%>25) and
low sensitivity (limit of detection≈2×10-8 mol/l). By this procedure, the precision (RSD%<7) and sensitivity (limit of detection≈8×10-10 mol/l) were improved. The method was applied to the determination of ATP in marine sediments and good recovery within 90–108%
was obtained. For non-polluted samples the measurement can be carried out by direct comparison with standard solutions. The
standard addition procedure is recommended for polluted samples.
Received: 25 April 1996/Revised: 28 June 1996/Accepted: 3 July 1996 相似文献
7.
A flow injection method for the sequential determination of iron(II) and iron(III) was developed. It is based on the differential
reaction kinetics of iron(II) and iron(III) with Tiron in a double-injection FI system. The proposed method employs the accelerating
action of copper(II) for the oxidation of iron(II) in the presence of Tiron. A linear calibration graph is obtained for iron
(II) and iron(III) in the concentration range 1.8 × 10–5– 1.8 × 10–4 mol/L; the throughput of samples is 30 injections/h.
Received: 22 October 1996 / Revised: 4 December 1996 / Accepted: 10 December 1996 相似文献
8.
Sérgio L. C. Ferreira Marcus L. S. F. Bandeira Valfredo A. Lemos Hilda C. dos Santos A. C. Spinola Costa Djane S. de Jesus 《Analytical and bioanalytical chemistry》1997,357(8):1174-1178
A simple and very sensitive method has been developed for the determination of ascorbic acid based on the oxidation of ascorbic
acid to dehydroascorbic acid by iron(III), followed by a complexation of iron(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol(Br-PADAP).
The iron(II) complex is formed immediately, with absorption maxima at 560 and 748 nm and a molar absorptivity of 1.31 × 105 l mole–1cm–1 and 5.69 × 104 l mole–1cm–1, respectively. The ascorbic acid determination is possible with a linear range up to 2.4 μg ml–1, a calibration sensitivity of 0.744 ml μg–1 at 560 nm and 0.323 ml μg–1 at 748 nm, and a detection limit of 15 ng ml–1 and 44 ng ml–1, respectively. The procedure was used for the ascorbic acid determination in several fruit juices and pharmaceutical formulations.
The results demonstrated a good precision (R.S.D. < 1%) and are in agreement with those obtained with others methods. The
Br-PADAP method proposed is six times more sensitive than the method using the iron(II)-1,10-phenanthroline system.
Received: 7 May 1996 / Revised: 1 July 1996 / Accepted: 8 August 1996 相似文献
9.
Sérgio L. C. Ferreira Marcus L. S. F. Bandeira Valfredo A. Lemos Hilda C. dos Santos A. C. Spinola Costa Djane S. de Jesus 《Fresenius' Journal of Analytical Chemistry》1997,357(8):1174-1178
A simple and very sensitive method has been developed for the determination of ascorbic acid based on the oxidation of ascorbic
acid to dehydroascorbic acid by iron(III), followed by a complexation of iron(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol(Br-PADAP).
The iron(II) complex is formed immediately, with absorption maxima at 560 and 748 nm and a molar absorptivity of 1.31 × 105 l mole–1cm–1 and 5.69 × 104 l mole–1cm–1, respectively. The ascorbic acid determination is possible with a linear range up to 2.4 μg ml–1, a calibration sensitivity of 0.744 ml μg–1 at 560 nm and 0.323 ml μg–1 at 748 nm, and a detection limit of 15 ng ml–1 and 44 ng ml–1, respectively. The procedure was used for the ascorbic acid determination in several fruit juices and pharmaceutical formulations.
The results demonstrated a good precision (R.S.D. < 1%) and are in agreement with those obtained with others methods. The
Br-PADAP method proposed is six times more sensitive than the method using the iron(II)-1,10-phenanthroline system.
Received: 7 May 1996 / Revised: 1 July 1996 / Accepted: 8 August 1996 相似文献
10.
A new simple, rapid and sensitive spectrophotometric flow injection method for the determination of trace iodide is described
based on an ion associate of iodate (IO3
–) with 2- (3,5-dibromo-2-pyridylazo)-5-diethylamino-phenol (3,5-Br2-PADAP) and thiocyanate (SCN–). In a strongly acidic medium, this unstable violet product was formed with an absorption maximum at 605 nm. Flow injection
is an ideal method to reproducibly monitor the transient signal. Various parameters were optimized using the Super Modified
Controlled Weighted Centroid Simplex Method (SMCWC). Under the optimum experimental conditions, iodide could be determined
in the range of 1.00 × 10–6 and 2.4 × 10–5 mol l–1. The correlation coefficient of the calibration curve is 0.9991. With a sampling frequency of 80 h–1, the detection limit for iodide is 5.0 × 10–7 mol l–1. The proposed method has been applied to the determination of trace iodide after oxidizing I– in table salt or laver to IO3
–. In addition, the mechanisms of the ion association reaction was studied.
Received: 15 August 1996 / Revised: 10 October 1996 / Accepted: 16 October 1996 相似文献
11.
A new procedure for the field characterization of the available amount of molybdenum in soil extract is described. It is
based on the preconcentration of the Mo(V)-SCN– complex into toluene solution of N-octylacetamide (OAA) and subsequent heating of the extract for ≈ 10 min at 60° C over
a water bath. The molar absorptivity of the complex is (3.50) × 104 1 mole–1 cm–1 at λmax 470 nm. The detection limit of the method is 4 ppb Mo. It provides a significantly increased tolerance limit for iron (up
to 1000 ppm) and is applicable to the field characterization of Mo in soil extracts.
Received: 29 May 1996 / Revised: 17 July 1996 / Accepted: 19 July 1996 相似文献
12.
A compact system for remote and non intrusive in situ analysis of fluorescent tracers using a newly developed pulsed microchip
laser coupled to fiber optics was used for in situ rhodamine determinations. By using a crystal doubling in front of the microchip
Nd-YAG laser, it is possible to obtain 532 nm at 5 kHz with an energy of 0.6 μJ in a 0.5 ns pulse. Using fiber optics and
a passive optode, it was possible to analyze remotely the fluorescence of rhodamine with a compact detection system (monochromator
and photomultiplier). Limits of detection down to 10–10–10–11 mol/L can be reached depending on the rhodamine studied. Such a laser can be directly implanted in the optode avoiding laser
losses when exciting in the U.V.
Received: 30 July 1997 / Revised: 6 October 1997 / Accepted: 10 October 1997 相似文献
13.
Electrocatalytic oxidation of thiosulfate on a modified nickel hexacyanoferrate film electrode 总被引:1,自引:0,他引:1
Xingyao Zhou Shengfu Wang Zhengpin Wang Mian Jiang 《Fresenius' Journal of Analytical Chemistry》1993,345(6):424-427
Summary A modified nickel hexacyanoferrate film glassy carbon electrode is prepared by the electrochemical deposition technique. The film is very stable upon voltammetric scanning in the potential range of 1.0 to –0.5 V (vs. SCE) and an oxidation peak occurs at 0.35 V (vs. SCE) (1 mol/l NaNO3). The effects of electrolyte, solvent, coexisting ions and other variables on the voltammetric behaviour of the modified film have been studied. The thickness of the resulting film can be controlled by changing the number of voltammetric cycles and the concentrations of nickel(II) and hexacyanoferrate(III) ions. The film shows catalytic activity towards electrooxidation of thiosulfate with a peak potential +0.5 V (K–-containing media). This oxidation potential of thiosulfate on the modified electrode is shifted negatively by about 550 mV as compared to the naked glassy carbon electrode. For practical application, the modified electrode can be used for the determination of thiosulfate in concentrations from 5.0×10–5 to 1.0×10–1 mol/l. This method has been successfully applied to the determination of thiosulfate in photographic waste effluents. 相似文献
14.
A compact system for remote and non intrusive in situ analysis of fluorescent tracers using a newly developed pulsed microchip
laser coupled to fiber optics was used for in situ rhodamine determinations. By using a crystal doubling in front of the microchip
Nd-YAG laser, it is possible to obtain 532 nm at 5 kHz with an energy of 0.6 μJ in a 0.5 ns pulse. Using fiber optics and
a passive optode, it was possible to analyze remotely the fluorescence of rhodamine with a compact detection system (monochromator
and photomultiplier). Limits of detection down to 10–10–10–11 mol/L can be reached depending on the rhodamine studied. Such a laser can be directly implanted in the optode avoiding laser
losses when exciting in the U.V.
Received: 30 July 1997 / Revised: 6 October 1997 / Accepted: 10 October 1997 相似文献
15.
S. Z. Qureshi M. I. H. Helaleh N. Rahman R. M. A. Q. Jamhour 《Analytical and bioanalytical chemistry》1997,357(7):1005-1007
A spectrophotometric determination of trimethoprim is described based on the reaction of its amine group with persulfate
which acts as a strong oxidizing agent in alkaline media. The reaction produces a stable yellow colored compound after heating
in a boiling water bath for 30 min. At λmax 355 nm, Beer’s law is obeyed in the concentration range 10–60 μg ml–1 with a molar absorptivity of 2.7 × 103 l mol–1cm–1. The method is applied to formulations with sulfamethoxazole.
Received: 30 July 1996 / Revised: 16 October 1996 / Accepted: 22 October 1996 相似文献
16.
Seven rain and 2 snow samples collected in October and November 1993 were analyzed by GFAAS. Manganese concentrations ranging
from 0.3 to 11.3 μg/L were found. pH-values (4.04–4.89, mean 4.52) and redox potentials (528–665 mV, mean 581 mV) were additionally
determined. This is important with respect to a qualified specification of Mn in atmospheric samples. A 0.45 μm-filtration
of the samples prior to GFAAS-analysis showed the same manganese concentrations in the filtrate as in the unfiltered samples.
Hence, the amount of solid Mn species in the investigated samples is negligible. For an examination of the oxidation state
of Mn some investigations concerning the stability of Mn(III) were carried out. They indicated that Mn(III) is unstable under
atmospheric conditions. For checking whether all the manganese in rainwater exists as Mn(II), a sensitive IC method for the
detection of Mn(II) was developed. By adapting a photometric procedure based on the oxidation of Leucomalachite Green (LMG)
to Malachite Green (MG) by permanganate (MnO-
4) to the IC-flow-through-system, a limit of determination of 1 μg/L Mn(II) could be achieved. A comparison of the IC measurements
with GFAAS-results of the filtered samples showed agreeing results. Thus, manganese in rainwater and snow exists entirely
as soluble Mn(II).
Received: 24 May 1996/Revised: 7 July 1996/Accepted: 14 July 1996 相似文献
17.
Seven rain and 2 snow samples collected in October and November 1993 were analyzed by GFAAS. Manganese concentrations ranging
from 0.3 to 11.3 μg/L were found. pH-values (4.04–4.89, mean 4.52) and redox potentials (528–665 mV, mean 581 mV) were additionally
determined. This is important with respect to a qualified specification of Mn in atmospheric samples. A 0.45 μm-filtration
of the samples prior to GFAAS-analysis showed the same manganese concentrations in the filtrate as in the unfiltered samples.
Hence, the amount of solid Mn species in the investigated samples is negligible. For an examination of the oxidation state
of Mn some investigations concerning the stability of Mn(III) were carried out. They indicated that Mn(III) is unstable under
atmospheric conditions. For checking whether all the manganese in rainwater exists as Mn(II), a sensitive IC method for the
detection of Mn(II) was developed. By adapting a photometric procedure based on the oxidation of Leucomalachite Green (LMG)
to Malachite Green (MG) by permanganate (MnO-
4) to the IC-flow-through-system, a limit of determination of 1 μg/L Mn(II) could be achieved. A comparison of the IC measurements
with GFAAS-results of the filtered samples showed agreeing results. Thus, manganese in rainwater and snow exists entirely
as soluble Mn(II).
Received: 24 May 1996/Revised: 7 July 1996/Accepted: 14 July 1996 相似文献
18.
The well-known method for the determination of selenium(IV), which is based on the cathodic stripping voltammetry of copper(I)
selenide, has been adapted for application at the thin-film mercury electrode on glassy carbon (TFME). Insufficient reproducibility
and sensitivity have been overcome by using a 0.1 mol/L HClO4 electrolyte solution containing 0.02 mol/L thiocyanate ions. Thiocyanate ions have been found to increase the peak height
of the selenium response and shift it to more positive potentials. This behaviour is explained by an adsorption of SCN– at the interface glassy carbon/Cu2Se and its action as an electron transfer catalyst between glassy carbon and copper(I) selenide. A 3σ-detection limit of 75
ng/L Se(IV) has been achieved. The relative standard deviation is 5.2% at 5 μg/L selenium(IV). The influence of cadmium(II), arsenic(III),
zinc(II), iron(III) and lead(II) ions on the selenium response has been studied. In case of lead ions, a new signal occurred
at more negative potentials than the reduction of Cu2Se. This signal, which is probably due to the reduction of PbSe, can also be used for the determination of selenium(IV).
Received: 13 November 1996 / Revised: 19 December 1996 / Accepted: 24 December 1996 相似文献
19.
A fluorescence quenching method for the determination of vanadium (V) based on the vanadium- catalyzed oxidation of rhodamine
6G (R6G) with periodate in the presence of ethylenediaminetetraacetic acid disodium salt (EDTA) in sulfuric acid medium is
described. The fluorescence was measured with excitation and emission wavelengths of 525 and 555 nm, respectively. The calibration
graph for vanadium (V) had linear ranges of 3.0 × 10−9–1.5 × 10−8 mol/l and 1.5 × 10−8–4.0 × 10−8 mol/l, respectively. The detection limit was 1.7 × 10−9 mol/l. The proposed method was successfully applied to the determination of vanadium (V) in river water, rain water and cast
iron samples.
Received June 29, 2001 Revision October 9, 2001 相似文献
20.
M N Matos Reyes M L Cervera M de la Guardia 《Analytical and bioanalytical chemistry》2009,394(6):1557-1562
A sensitive and simple analytical method has been developed for determination of Sb(III), Sb(V), Se(IV), Se(VI), Te(IV), Te(VI),
and Bi(III) in garlic samples by using hydride-generation–atomic-fluorescence spectrometry (HG–AFS). The method is based on
a single extraction of the inorganic species by sonication at room temperature with 1 mol L−1 H2SO4 and washing of the solid phase with 0.1% (w/v) EDTA, followed by measurement of the corresponding hydrides generated under two different experimental conditions directly
and after a pre-reduction step. The limit of detection of the method was 0.7 ng g−1 for Sb(III), 1.0 ng g−1 for Sb(V), 1.3 ng g−1 for Se(IV), 1.0 ng g−1 for Se(VI), 1.1 ng g−1 for Te(IV), 0.5 ng g−1 for Te(VI), and 0.9 ng g−1 for Bi(III), in all cases expressed in terms of sample dry weight. 相似文献