Indirect ultraviolet determination of silver with nickelocyanide ion by flow injection analysis

A flow-injection method for the ultraviolet spectrophotometric determination of silver, based on its reaction with nickelocyanide ion, Ni(CN)²⁻₄, in ammoniacal buffer medium (pH 10) and subsequent measurement of the decrease in the absorption of the Ni(CN)²⁻₄ complex at 275 nm is described. The calibration graph is linear in the range 10–400 μm silver. At a sampling rate of about 60 samples h⁻¹ with 35 μl sample injections, precision was about 1% relative standard deviation. The proposed method was successfully applied to the determination of silver in some common silver minerals.     

Carbon paste electrode modified with silver thimerosal for the potentiometric flow injection analysis of silver(I)

The utility of carbon paste electrode modified with silver ethylmercurythiosalicylate (silver thimerosal) in both static mode and flow injection analysis (FIA) is demonstrated. The electrode was fully characterized in terms of composition, response time, thermal stability, usable pH and ionic strength ranges. It has been shown that diisononyl phthalate (DINP) acts as more suitable solvent mediator for preparation of the electrode, which exhibits linear response range to Ag(I) extending from 5.0 × 10⁻⁷ to 1.0 × 10⁻³ M with detection limit of 2.5 × 10⁻⁷ M and Nernstian slope of 59.3 ± 1.0 mV/decade. The proposed chemically modified carbon paste electrode shows a very good selectivity for Ag(I) over a wide variety of metal ions and successfully used for the determination of the silver content of silver sulphadiazine (burning cream) and developed radiological films. The electrode was also used as an indicator electrode in the potentiometric titration of thiopental and thimerosal with AgNO₃.     

Catalytic kinetic simultaneous determination of iron, silver and manganese with the Kalman filter by using flow injection analysis stopped-flow spectrophotometry

A catalytic differential kinetic method with Kalman filter for the simultaneous determination of multi-component is described. The oxidization of Rhodamine B (RB) by potassium periodate in a slightly acid solution is a slow reaction. But iron(III), silver(I) or manganese(II) has a differential catalytic effect on the oxidation reaction of RB in the presence of 1,10-phenanthroline as the activator. So iron, silver and manganese can be simultaneously determined by measuring the decreasing absorbance of the dye (RB) at 555 nm. A flow injection analysis stopped-flow spectrophotometric system with a microcomputer performs the determinations. This method has been applied to determining iron, silver and manganese of alloy samples with satisfactory results.     

On-line determination of mercury(II) by membrane separation flow injection analysis

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).     

Catalytic-fluorimetric determination of EDTA and iron(III) by flow injection analysis

Summary In this paper the authors report on several methods for the direct determination of EDTA and indirect determination of iron(III), based on the inhibition effect of EDTA on the catalytic action of copper (II) on the oxidation of 2,2-dipyridyl ketone hydrazone by hydrogen peroxide and on the decrease of this inhibition effect in the presence of Fe(III), respectively. These methods allow the determination of EDTA in the ranges of 0.4–2.0 g · ml^–1 and 0.2–1.0 g · ml^–1 for the normal and reversed FIA modes, respectively, and of 40–240 ng · ml^–1 for Fe(III) by reversed FIA.

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Katalytisch-fluorimetrische Bestimmung von EDTA und Eisen(III) durch FließinjektionsanalyseInhibitionsmethoden

Zusammenfassung Verfahren zur direkten Bestimmung von EDTA sowie zur indirekten Bestimmung von Eisen(III) werden beschrieben. Sie beruhen auf der Inhibitorwirkung von EDTA auf den katalytischen Effekt von Kupfer(II) bei der Oxidation von 2,2-Dipyridylketonhydrazon mit Wasserstoffperoxid bzw. auf der Schwächung dieser Inhibitorwirkung in Gegenwart von Eisen(III). Es ist mit diesen Methoden möglich, EDTA im Bereich von 0,4–2,0 g/ml (normale FIA) bzw. 0,2–1,0 g/ml (umgekehrte FIA) und Eisen im Bereich von 40–240 ng/ml (umgekehrte FIA) zu bestimmen.

     

流动注射化学发光法测定佐米曲谱坦

在碱性条件下,佐米曲谱坦对鲁米诺-K3[Fe(CN)6]化学发光体系有较强的抑制作用,据此建立了佐米曲谱坦的流动注射化学发光分析法。该法的化学发光抑制值ΔI与佐米曲谱坦质量浓度在2.0×10-6~1.2×10-4g/mL范围内,呈良好的线性关系,检出限为7.6×10-7g/mL。对2.5×10-5g/mL佐米曲谱坦测定的相对标准偏差为1.2%(n=11)。方法适用于佐米曲谱坦片中佐米曲谱坦的测定。     

流动注射化学发光法测定司帕沙星的研究

在酸性介质中,司帕沙星对NaNO2-H2O2发光体系有很强的增强作用,并且其增强化学发光强度与司帕沙星的物质的量浓度在一定范围内呈线性关系。基于此,采用流动注射技术,建立了一种简单、快速测定司帕沙星的方法。线性范围为1.0×10-7~8.5×10-4mol/L,检出限为6.5×10-8mol/L。利用该法测定了司帕沙星片剂中的司帕沙星,回收率在98.8%~104.4%之间。     

流动注射化学发光法测定那格列奈

在碱性介质中,那格列奈对Luminol-H2O2体系的化学发光有很强的抑制作用,据此建立了流动注射化学发光抑制法测定那格列奈的新方法.该法的化学发光抑制值△I与那格列奈的质量浓度在2.0×10-8～1.0×10-6 g/mL范围内,呈良好的线性关系,检出限为1.4×10-8 g/mL;对4.0×10-7 g/mL那格列奈连续进行11次平行测定,相对标准偏差为1.0%;通过对荧光光谱的研究,对机理进行了初步探讨.     

流动注射分光光度法同时测定Fe(Ⅱ)和Fe(Ⅲ)

将流动注射技术引入邻菲罗啉分光光度法测定Fe2+分析体系,采用单阀双带镀镉锌片还原柱带隔离的阀体流路,建立了同时测定微量Fe2+和Fe3+的分析方法。Fe2+的测定范围为0~10 mg/L,检出限为1.2×10-6mg/L;Fe3+的测定范围为0~12 mg/L,检出限为1.8×10-6mg/L。方法用于水中Fe2+和Fe3+的同时测定。     

Simultaneous spectrofluorimetric determination of cerium(III) and cerium(IV) by flow injection analysis

Cerium(III) (1–100 μg l^?1) is determined by injection into a carrier stream of hydrochloric, perchloric or sulphuric acid, and monitoring its native fluorescence. Cerium(IV) can be determined similarly by incorporating a zinc reductor minicolumn into the system. Splitting the injection sample so that only part passes through the reductor, and the remainder by-passes it, allows total cerium and cerium(III) to be detected from the two sequential fluorescence peaks obtained.     

Catalytic determination of silver

Summary Ethylenediamine is proposed as activator for the oxidation of sulphanilic acid with persulphate, catalysed by traces of silver(I). The kinetic equations of the uncatalysed and the catalytic reactions were studied, as well as the influence of the acidity, the temperature and the activator concentration. On that basis a catalytic method is developed for determination of 1–35 ng of Ag⁺ per ml with 2.3% relative error. The influence of 17 ions which usually accompany silver was also studied.

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Zusammenfassung Äthylendiamin wurde als Aktivator für die durch Silber katalysierte Oxydation von Sulfanilsäure mit Persulfat vorgeschlagen. Die kinetischen Reaktionsgleichungen der unkatalysierten und der katalysierten Reaktion wurden geprüft, der Einfluß der Acidität, der Temperatur und der Aktivatorkonzentration untersucht. Auf dieser Grundlage wurde eine katalytische Bestimmungsmethode für 1 bis 35 ng Ag/ml ausgearbeitet, deren relative Fehlerbreite 2,3% beträgt. Der Einfluß von 17 üblichen Begleitionen des Silbers wurde ebenfalls untersucht.

     

流动注射化学发光法测定氨苄西林的研究

氨苄西林在NaOH溶液中降解后,其产物可在酸性条件下与KMnO4发生化学发光反应,甲醛的存在可使发光强度增强。据此,采用流动注射技术,建立了一种测定氨苄西林的化学发光分析法。方法的检出限为9.1×10-9g/mL,相对标准偏差为1.8%(n=11,ρ=3.4×10-6g/mL),线性范围为4.0×10-8~2.0×10-5g/mL。利用该法测定了氨苄西林胶囊中的氨苄西林,其回收率在87%~106%。     

Chemiluminescence determination of bufrenorphine hydrochloride by flow injection analysis

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).     

Continuous flow and flow injection stripping voltammetric determination of silver(I), mercury(II), and bismuth(III) at a bulk modified graphite tube electrode

The epoxy-impregnated graphite tube electrode bulk modified with 2-mercaptobenzoxazole, employed in a wall-jet configuration, was found to be useful for the continuous flow and flow injection stripping voltammetric determinations of Ag^I, Hg^II and Bi^III. For continuous flow, detection limits for Ag^I, Hg^II and Bi^III were 1.8 × 10⁻¹⁰ M, 1.9 × 10⁻⁹ M and 9.5 × 10⁻⁹ M, respectively (10 min accumulation, S/N = 3). Precisions for 5.00 × 10⁻⁹ M Ag^I, 1.00 × 10⁻⁸ M Hg^II and 1.00 × 10⁻⁷ M Bi^III were 10.5%, 5.77 % and 7.90% (relative standard deviations, n = 6), respectively. In the case of flow injection stripping, with a 500 μL injection loop, detection limits of 0.59 ng, 2.0 ng and 120 ng were obtained for Ag^I, Hg^II and Bi^III, respectively (S/N = 3). Selected metal ions, inorganic and organic substances were investigated for interferences. The electrode was tested with a certified sample and then applied to the determinations of the metal ions in a urine and a sea-water sample.     

顺序注射催化动力学光度法测定织物和室内空气中痕量甲醛

在磷酸介质中 ,甲醛可以催化溴酸钾氧化　花青的反应使其退色 ,据此建立了顺序注射催化动力学光度法测定织物和室内空气中痕量甲醛的新方法。方法的线性范围 0 .5～ 7.0 μg mL ,检出限 0 .1 μg mL。用于树脂整理特殊织物和室内空气中痕量甲醛的测定 ,回收率在 97.0 %～ 1 0 5 .0 %之间。     

Spectrofluorimetric kinetic determination of selenium (IV) by flow injection analysis in cationic micellar medium

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.     

Catalytic determination of traces of silver(I) using the oxidation of Janus Green with peroxodisulfate.

A method for sensitive and selective determination of silver based on the catalytic effect of silver(I) ion on the oxidation of Janus Green by peroxodisulfate is described. o-Phenanthroline is used as an activator. The rate of the decrease in absorbance of Janus Green (at 615 nm) is proportional to the concentration of silver in the range of 0.3-4.0 ng mL(-1) and 4.0-500.0 ng mL(-1). The theoretical limit of detection was 0.25 ng mL(-1). The method is free from most interferences. The method was applied to the determination of silver in plants (the uptake of silver by plants), in photographic solutions, lake water and several synthetic samples.     

Ultrasensitive determination of DNA sequences by flow injection chemiluminescence using silver ions as labels

We presented a new strategy for ultrasensitive detection of DNA sequences based on the novel detection probe which was labeled with Ag⁺ using metallothionein (MT) as a bridge. The assay relied on a sandwich-type DNA hybridization in which the DNA targets were first hybridized to the captured oligonucleotide probes immobilized on Fe₃O₄@Au composite magnetic nanoparticles (MNPs), and then the Ag⁺-modified detection probes were used to monitor the presence of the specific DNA targets. After being anchored on the hybrids, Ag⁺ was released down through acidic treatment and sensitively determined by a coupling flow injection–chemiluminescent reaction system (Ag⁺–Mn²⁺–K₂S₂O₈–H₃PO₄–luminol) (FI–CL). The experiment results showed that the CL intensities increased linearly with the concentrations of DNA targets in the range from 10 to 500 pmol L⁻¹ with a detection limit of 3.3 pmol L⁻¹. The high sensitivity in this work may be ascribed to the high molar ratio of Ag⁺–MT, the sensitive determination of Ag⁺ by the coupling FI–CL reaction system and the perfect magnetic separation based on Fe₃O₄@Au composite MNPs. Moreover, the proposed strategy exhibited excellent selectivity against the mismatched DNA sequences and could be applied to real samples analysis.