共查询到20条相似文献,搜索用时 15 毫秒
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Paolo Rumori 《Analytica chimica acta》2003,486(2):227-235
Two new flow methods, flow injection analysis (FIA) and sequential injection analysis (SIA), for the spectrophotometric determination of Cu(II) in water at trace levels have been developed and optimised. Both methods are based on the reaction with oxalic acid bis(cyclohexylidene hydrazide) (cuprizone) in alkaline media. The two procedures have been developed for the final aim to compare their performances and to offer new rapid heavy metals analysis tools, avoiding the use of extraction steps. A detailed study of the physico-chemical parameters affecting the systems performances has been carried out. The reversed FIA and sandwich SIA approaches offered the best sensitivity. In both cases, an extremely good linearity has been obtained within the range 0.06-4 μg ml−1 (correlation coefficient r=0.9999), whereas the observed detection limits were 0.013 and 0.004 μg ml−1, for FIA and SIA, respectively. Furthermore, due to the great similarity of the diffusion zones in the reaction slugs, our approach offers the opportunity to compare the two methods in analogous conditions. This SIA method, besides keeping its typical reagent saving features, offered analytical performances equivalent to those of FIA. To obtain these results, an original “stop-flow like” method was successfully employed in the SIA approach. Both methods were validated by analysis of real water samples, after copper addition, and certified reference samples of fortified and waste waters. 相似文献
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Titanium(III) and iron(II) are shown to stimulate luminol chemiluminescence in the absence of added oxidant. Down to 10?9 M titanium can be determined. Both metal ions also produce chemiluminescence when injected into 0.1 M carbonate buffer (pH 10.4), allowing >10?6 M of each to be determined. The intensities are greater when the solutions have been deoxygenated by a stream of nitrogen, and when rhodamine B is used as a sensitizer. 相似文献
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A direct, simple and rapid flow-injection method is described for determining buprenorphine hydrochloride (10?8–10?4 M) based on its chemiluminescent oxidation with potassium permanganate in polyphosphoric acid. The limit of detection is 1 × 10?8 M (0.5 pmol per injection) and the log-log calibration is linear up to 1 × 10?4 M; the r.s.d. is 0.7% for a 10 μg ml?1 solution (n = 10). The method is directly applicable to aqueous solutions of tablets containing the drug (0.2 mg/tablet). 相似文献
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A procedure is reported for the simultaneous determination of binary mixtures of cobalt(III)-copper(II) and cobalt(III)-nickel(II) by differential kinetic methods based on complex formation reactions with 3-(1H-1,2,4-triazolyl-3-azo)-2,6-diaminotoluene. The single-point method is used in both cases. The simultaneous determination of Co-Cu and Co-Ni is possible in the concentration range from 10/1 to 1/1. The interference caused by various ions is also studied. The method has been used to determine cobalt-copper and cobalt-nickel mixtures in synthetic samples, hydrofining catalysts and low alloy steels. 相似文献
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A novel chemiluminescence (CL) flow system has been developed for the sequential determination of Fe(II) and Fe(III) in water.
Fe(II) was detected by its catalytic effect on the CL reaction between luminol immobilized on an anion exchange resin column
and dissolved oxygen; Fe(III) was determined by difference measurement after on-line conversion to Fe(II) in a reducing mini-column
packed with Cu plated Zn granules. For both ions, the calibration graph was linear in the range 1 × 10–9 to 1 × 10–6 g/mL, and the detection limit was 4 × 10–10 g/mL. A complete analysis could be performed in 1.5 min with a relative standard deviation of less than 5%. The system could
be reused for over 200 times and has been applied successfully to the determination of Fe(II) and Fe(III) in natural water
samples.
Received: 13 March 1997 / Revised: 3 June 1997 / Accepted: 6 June 1997 相似文献
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A novel chemiluminescence (CL) flow system has been developed for the sequential determination of Fe(II) and Fe(III) in water. Fe(II) was detected by its catalytic effect on the CL reaction between luminol immobilized on an anion exchange resin column and dissolved oxygen; Fe(III) was determined by difference measurement after on-line conversion to Fe(II) in a reducing mini-column packed with Cu plated Zn granules. For both ions, the calibration graph was linear in the range 1 × 10–9 to 1 × 10–6 g/mL, and the detection limit was 4 × 10–10 g/mL. A complete analysis could be performed in 1.5 min with a relative standard deviation of less than 5%. The system could be reused for over 200 times and has been applied successfully to the determination of Fe(II) and Fe(III) in natural water samples. 相似文献
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Takeshi Yamane 《Mikrochimica acta》1984,82(5-6):425-433
Summary A catalytic method in a flow injection system is proposed for the simple, rapid and sensitive determination of trace amounts of cobalt; the method is based on the cobalt-catalyzed oxidation of protocatechuic acid by hydrogen peroxide. The reported method has a limit of detection of 0.2 ppb by injecting 75l of sample, corresponding to 15 pg cobalt, and permitsca. 50 determinations per hour with a relative standard deviation of 1.5%. Relatively good selectivity is also obtained.
Katalytische Bestimmung von Kobalt-Spuren mit der Protocatechusäure-Wasserstoffperoxid-Reaktion in einer Flie-Injektions-Vorrichtung
Zusammenfassung Eine einfache, schnelle und empfindliche Bestimmung von Kobaltspuren wurde beschrieben. Sie beruht auf der durch Kobalt katalysierbaren Oxydation von Protocatechusäure durch Wasserstoffperoxid. Bei Injektion von 75l Probe (entsprechend 15 pg Co) beträgt die Erfassungsgrenze des Verfahrens 0,2 ppb. 50 Bestimmungen sind pro Stunde durchführbar; die relative Standardabweichung beträgt 1,5%. Die Selektivität ist relativ gut.相似文献
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Voltammetric determination of traces of cobalt(II) with a chemically modified carbon paste electrode
Summary A new preconcentration and voltammetric determination method for cobalt(II) in aqueous solution with a chemically modified electrode is proposed. The accumulation behaviour and voltammetry of cobalt(II) has been investigated with a carbon paste electrode modified with cationexchanger and 1,10-phenanthroline. The electrochemical response is characterized with respect to carbon paste composition, pH, preconcentration time, cobalt(II) concentration and other variables. For a 3-min preconcentration time, the electrode gives good linearity for 1×10–7 to 4×10–6 mol/l Co(II), a detection limit of 8×10–8 mol/l. The response can be reproduced with a 4.0% relative standard deviation. The method is fairly free from many coexisting ions interferences. A rapid and convenient renewal procedure allows the use of a single electrode in multiple analytical determinations over several days. Satisfactory results are obtained for the determination of cobalt in a variety of certified standard reference materials. 相似文献
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A rapid and inexpensive gas-diffusion (GD) flow injection method for the on-line determination of Hg(II) in aqueous samples is described. The analytical procedure involves the injection of a Hg(II) sample into a 1.5 M H2SO4 carrier stream which is merged with a reagent stream containing 0.6% SnCl2 and 1.5 M H2SO4. Under these conditions Hg(II) is reduced to metallic mercury which partially evaporates through a Teflon membrane into an acceptor stream containing 1.75×10−4 M KMnO4 in 0.3 M H2SO4. The decrease in the absorbance of the acceptor stream at 528 nm corresponding to the absorption maximum of the permanganate anion can be related to the original concentration of Hg(II) in the sample. The method is characterized by a detection limit of 4 μg l−1 and a sampling frequency of 8 h−1. The flow system was successfully applied to the analysis of river samples spiked with Hg(II). 相似文献
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Alberto Chisvert A. Salvador M.-C. Pascual-Martí Joan G. March 《Analytical and bioanalytical chemistry》2001,369(7-8):684-689
Spectrophotometric determination of a widely used UV-filter, such as oxybenzone, is proposed. The method is based on the complexation reaction between oxybenzone and Ni(II) in ammoniacal medium. The stoichiometry of the reaction, established by the Job method, was 1:1. Reaction conditions were studied and the experimental parameters were optimized, for both flow injection (FI) and sequential injection (SI) determinations, with comparative purposes. Sunscreen formulations containing oxybenzone were analyzed by the proposed methods and results compared with those obtained by HPLC. Data show that both FI and SI procedures provide accurate and precise results. The ruggedness, sensitivity and LOD are adequate to the analysis requirements. The sample frequency obtained by FI is three-fold higher than that of SI analysis. SI is less reagent-consuming than FI. 相似文献
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Chisvert A Salvador A Pascual-Martí MC March JG 《Fresenius' Journal of Analytical Chemistry》2001,369(7-8):684-689
Spectrophotometric determination of a widely used UV-filter, such as oxybenzone, is proposed. The method is based on the complexation reaction between oxybenzone and Ni(II) in ammoniacal medium. The stoichiometry of the reaction, established by the Job method, was 1:1. Reaction conditions were studied and the experimental parameters were optimized, for both flow injection (FI) and sequential injection (SI) determinations, with comparative purposes. Sunscreen formulations containing oxybenzone were analyzed by the proposed methods and results compared with those obtained by HPLC. Data show that both FI and SI procedures provide accurate and precise results. The ruggedness, sensitivity and LOD are adequate to the analysis requirements. The sample frequency obtained by FI is three-fold higher than that of SI analysis. SI is less reagent-consuming than FI. 相似文献
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流动注射化学发光法快速测定化学需氧量 总被引:5,自引:0,他引:5
基于酸性K2 Cr2 O7在消解水体中的有机污染物时被还原为Cr(Ⅲ ) ,而Cr(Ⅲ )可以催化Luminol H2 O2 体系产生强的化学发光 ,建立了一种测定COD的流动注射化学发光法。本方法不需要催化剂 ,不需要长的消解时间 ,可以采用较低的酸度 ,适合于在线连续检测水体COD。本方法检测COD的线性范围为 2 0~1 0 0 0 0mg L ,检出限为 1 0mg L ,对 1 0mg LCOD的 1 1次平行测定的RSD小于5 %。方法已用于地表水样COD的测定。 相似文献
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Chemiluminescence determination of sodium 2-mercaptoethane sulfonate by flow injection analysis using cerium(IV) sensitized by quinine 总被引:1,自引:0,他引:1
A flow injection method with chemiluminescence (CL) detection is proposed for the determination of sodium 2-mercaptoethane sulfonate (MESNA), a drug often used to reduce the urotoxic effects of antineoplastic alkylating agents. The procedure is based on the reaction of the thiol with Ce(IV) in a sulfuric acid medium and measurement of the CL intensity produced by quinine used as a sensitizer. The optimum conditions for CL emission were investigated. Using the CL peak height as the analytical parameter, MESNA was determined over the concentration range 0.29–2.21 ng (1.97–9.85 μg·l−1) with a detection limit of 0.21 ng (1.38 μg·l−1) and a relative standard deviation (R.S.D.) of 4.1%. The method was applied satisfactorily to the determination of MESNA in pharmaceutical preparations with percentages of recovery between 94 and 105. 相似文献
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A simple method for the selective and sensitive kinetic spectrophotometric determination of iron (II) is described. The method
is based on the oxidation reaction of reduced phenolphthalein by periodate in alkaline media. The change in absorbance was
measured using the fixed time method. The effect of different variables on the reaction was investigated and optimum conditions
were obtained. The calibration curve was linear in the range 50–3000 ng/mL, and a detection limit of 17 ng/mL was obtained.
The relative standard deviation of ten replicate determinations of 200 ng/mL of Fe(II) was 1.2%. The determination of Fe(II)
in the presence of a 50-fold amount of Fe(III) could be carried out.
This article was submitted by the authors in English. 相似文献
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A highly sensitive potentiometric flow injection analysis method for the determination of manganese(II), utilizing a redox reaction with hexacyanoferrate(III) in near neutral media containing ammonium citrate is described. The analytical method is based on the detection of the change in potential of a flow-through type redox electrode detector, resulting from the composition change of an [Fe(CN)6]3−-[Fe(CN)6]4− potential buffer solution. A linear relationship between the potential change (peak height) and the concentration of manganese(II) was found. Manganese(II) in a wide concentration range from 10−4 to 10−7 M could be determined by appropriately altering the concentration of the potential buffer from 10−3 to 10−5 M. The lower detection limit of manganese(II) was determined to be 1×10−7 M. The sampling rate and relative standard deviation were 20 h−1 and 1.9% (n=8) for 6×10−6 M manganese(II), respectively. The proposed method was successfully applied to the determination of manganese(II) in actual soil samples obtained from tea fields. Analytical results obtained by the proposed method were in good agreement with those obtained by an atomic absorption spectrophotometric method. 相似文献