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This paper describes the application of the well-known Molybdenum Blue method for selective determination of arsenite in a flow injection system. Selectivity is achieved by on-line separation of the main interferents phosphate, arsenate and silicate using a strong anion-exchange microcolumn located in the aspiration line of injection valve. Arsenite passing through the microcolumn unretained is determined using Molybdenum Blue method following in-line oxidation to arsenate by permanganate. A thorough investigation of optimal experimental conditions for both, the separation of interferents and sensitive detection of arsenite is presented. The method developed permits arsenite to be determined in the concentration range 5-500 microg/l with high precision and reliability. A sample throughput of 20 hr(-1) is achieved. Phosphate, arsenate and silicate do not interfere at concentration levels significantly higher than that of arsenite. The application to real water samples reveals excellent recovery of spiked samples and the absence of matrix interferences. 相似文献
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Gallium can be determined fluorunetrically, with linear response in the range 2.2 × 10-5 M–1.08 × 10-4 M, by means of chelate formation with lumogallion ; fluorescence is enhanced by mixing with a polyethylene glycol monolauryl ether solution. Up to 10-fold molar amounts of aluminum can be tolerated, because of the slow formation rate of the aluminum—lumogallion chelate. 相似文献
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Gong A Zhu X Huang X Zhang Y 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,69(1):189-192
In this work, a new flow injection analysis (FIA) for the determination of Pb(2+) in Chinese medicinal herbs was developed. In the buffer solution of borax-NaOH (pH 10.5), Pb(2+) reacted with 2-[(5-bromo-2-pyridyl)-azo]-5-(diethyl-amino)phenol (5-Br-PADAP) to form a complex. The experimental results showed that the sensitivity was enhanced in the presence of polyethyleneglycol-800 (PG-800). The main factors affecting the determination were investigated in detail. Under the optimum conditions, the linear range and detection limit is 0.0-0.3microg/mL and 1.5ng/mL (correlation coefficient r=0.9996), respectively. The linear regression equation is A=-0.005+0.60c (microg/mL). The sample throughout is 10h(-1). Foreign substrates effects were also investigated. The proposed method has been successfully applied to the determination of lead in reference material, goldthread and lepidium seed. 相似文献
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A sensitive catalytic kinetic spectrofluorimetric method for determining ng ml(-1) of selenium by flow injection analysis has been developed. The method, based on the catalytic effect of Se (IV) on the reduction of resorufin by sulphide, in the presence of cetylpyridinium chloride, is monitored spectrofluorimetrically (lambda(ex)=480 nm; lambda(em)=583 nm). The linearity range of the calibration graph is dependent on the concentration of sulphide. The variables affecting the rate of the reaction were investigated. The method is simple, rapid, precise, sensitive, and widely applicable. The limit of detection is 1 ng ml(-1) Se (IV), and the calibration range is 5-1000 ng ml(-1). Sampling rate is 60 samples h(-1), and the relative standard deviation of 12 determinations of 100 ng ml(-1) Se was 0.76%. The determination of Se (IV) in the presence of Se (VI) and total selenium is described. The method was applied to the determination of Se in selenium tablets, and several synthetic samples. 相似文献
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Chromium(II) and vanadium(II) in acidic medium are applied as powerful reducing agents in flow injection analysis. Detection is done amperometrically. For the determination of nitrite with chromium(II), the limit of determination is 5 × 10?6 mol l?1 with a linear range up to 7.5 × 10?5 mol l?1, similar to the case of uranium(III). Vanadium(II) is less suitable for the determination of nitrite. Nitrate, hydroxylamine and hydrazine could not be determined with these reagents. 相似文献
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Copper(II) ions (1–20 mg l?1) are determined at 385 nm by injection into an aqueous carrier solution containing EDTA (0.05 M), carbon disulphide (0.03%) and diethanolamine (0.1%) in aqueous ammonia solution (0.5%) adjusted to pH 8.0. Chromium(VI) and, to a minor extent, iron(III) interfere. In the absence of EDTA, cobalt, iron(II), nickel, and manganese ions interfere but the sensitivity to copper is higher. 相似文献
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Jason W Costin 《Analytica chimica acta》2003,480(1):67-77
The determination of the amino acids proline, histidine, tyrosine, arginine, phenylalanine and tryptophan using flow injection analysis (FIA) with chemiluminescence detection is described. Proline was the only amino acid to exhibit chemiluminescence with the tris(2,2-bipyridyl)ruthenium(III) reaction at pH 10. While, histidine was found to selectively enhance the reaction of luminol with Mn(II) salts in a basic medium. Acidic potassium permanganate chemiluminescence was able to selectively determine tyrosine at pH 6.75. Low pressure separations using a C18 guard column allowed the simultaneous determination of tyrosine and tryptophan or phenylalanine and tryptophan with acidic potassium permanganate and copper(II)-amino acid-hydrogen peroxide chemiluminescence, respectively. Precision for each method was less than 3.9% (R.S.D.) for five replicates of a standard (1×10−5 M) and the detection limits ranged between 4×10−9 and 7×10−6 M. Preliminary investigations revealed that the methodology developed was able to selectively determine the individual amino acids in an equimolar mixture of the 20 naturally occurring amino acids. 相似文献
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Spectrophotometric determination of nitrite in foodstuffs by flow injection analysis 总被引:1,自引:0,他引:1
A simple method for the determination of nitrite in foodstuffs by flow injection analysis is described. Nitrite samples are prepared in a microwave oven, treated with a 1 mol/lNH4Cl solution at a pH of 9 (all under nitrogen atmosphere) and are immediately analysed. Nitrite is diazotised in the FIA system with N-(1-naphthyl) ethylenediammonium dichloride to form the highly coloured azo dye, which is measured at 540 nm. The detection limit is 0.036 mg/kg for sample injections of 400 l. The sampling rate is about 50 samples per hour and the relative standard deviation is 0.67%. 相似文献
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The proposed method is based on the reduction of blue tetrazolium by the steroid in an alkaline medium to form a highly colored formazan. The effects of reagent concentration, temperature, flow rate, and manifold design on the reaction are discussed for a typical steroid, methylprednisolone acetate. Analytical readout is obtained within 30 s after sample introduction and up to 100 samples/h can be processed with baseline resolution between peaks. Typical relative standard deviations of 0.5% are obtained with 10-μ1 injection volumes. Results obtained by flow injection analysis are similar to those obtained with the AutoAnalyzer technique. 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 simple and sensitive flow injection analysis-atomic absorption spectrometric procedure is described for the determination of cobalt. The method is based upon on-line preconcentration of cobalt on a microcolumn of 2-nitroso-1-naphthol immobilized on surfactant coated alumina. The trapped cobalt is then eluted with ethanol (250 μl) and determined by flame atomic absorption spectrometry. The analytical figures of merit for the determination of cobalt are as follows: detection limit (3 S), 0.02 ng ml−1; precision (RSD), 2.8% for 20 ng ml−1 and 1.7% for 70 ng ml−1 of cobalt; enrichment factor, 125 (using 25 ml of sample). The method has been applied to the determination of cobalt in water samples, vitamin B12 and B-complex ampoules and accuracy was assessed through recovery experiment and independent analysis by furnace AAS. 相似文献
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A. Fernández M. D. Luque de Castro M. Valcárcel 《Fresenius' Journal of Analytical Chemistry》1987,327(5-6):552-554
Summary Two automatic methods are proposed for the voltammetric determination of ethanol in whole blood. They are based on the use of the enzymatic systems alcohol dehydrogenase/ nicotinamide adenine dinucleotide (method A) and alcohol dehydrogenase/nicotinamide adenine dinucleotide/ diaphorase/2,6-dichlorophenolindophenol (method B). The determination ranges are 2.5–30.0 g/ml and 0.5–30.0 g/ml with sampling rates of 60 and 30 samples/h, respectively. The coefficients of variation are about ±4%.
Voltammetrisch-enzymatische Bestimmung von Ethanol in Vollblut durch Fließinjektionsanalyse相似文献
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利用肼类化合物在酸性介质中与香草醛反应形成黄色腙类化合物,在波长410nm处具有最大的光度吸收,建立了流动注射分析(FIA)技术与分光光度法联用直接测定环境水样中的微量肼的在线分析方法.结果表明,在最佳检测条件下,肼在2~1500μg/L范围内有良好的线性关系,相关系数R<'2>=0.9998,检测限为0.7μg/L,每小时进样20次,100μg/L的肼样品相对标准偏差(RSD)为0.92%(n=11).利用该方法分析河水、井水、池塘水、污水中的肼,回收率为97.3%~106.1%,结果与国家标准法一致. 相似文献
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Bromide can occur in well waters as a result of sea water intrusion. The phenol red method is adapted to a flow-injection system and interferences are studied by using a two-channel valve. Standards are injected from one loop of the valve while the possible interferent is injected from the other loop; this provides a fast means of evaluating interferences. Ammonia, cyanide and humic substances interfere. Bromide can be determined down to 2 μM at a rate of 80 samples per hour 相似文献