An improved flow-injection system for spectrophotometric determination of molybdenum and tungsten in tool steels

A flow-injection procedure for simultaneous spectrophotometric determination of tungsten and molybdenum in steel alloys is proposed. The method exploits the catalytic effects of Mo(VI) and W(VI) on the rate of iodide oxidation by hydrogen peroxide under acidic conditions. A novel strategy for ion-ex...

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Published inTalanta (Oxford) Vol. 69; no. 4; pp. 927 - 931
Main Authors Gervasio, Ana P.G., Fortes, Paula R., Meneses, Silvia R.P., Miranda, Carlos E.S., Zagatto, Elias A.G.
Format Journal Article
LanguageEnglish
Published Amsterdam Elsevier B.V 15.06.2006
Oxford Elsevier
Subjects
Analytical chemistry
Catalytic determination
Chemistry
Exact sciences and technology
Flow analysis
In-line ion exchange
Molybdenum
Sample injection
Spectrometric and optical methods
Spectrophotometry
Tungsten
Sample injection
Tungsten
In-line ion exchange
Spectrophotometry
Molybdenum
Flow analysis
Catalytic determination
Hydrogen peroxide
Atomic emission spectrometry
Citrate
Inductive coupling plasma spectrometry
Alloy steel
Accuracy
Tungsten VI
Oxidation
Ion exchange
Flow injection
Catalytic reaction
Cationic resin
Iodides
Coupled method
Molybdenum alloy
Simultaneous measurement
Molybdenum VI
Reference material
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Summary:A flow-injection procedure for simultaneous spectrophotometric determination of tungsten and molybdenum in steel alloys is proposed. The method exploits the catalytic effects of Mo(VI) and W(VI) on the rate of iodide oxidation by hydrogen peroxide under acidic conditions. A novel strategy for ion-exchange separation of the potential interfering species is proposed, and an AG50W-X8 cationic resin mini-column is used. The sample is injected twice, originating two sequential plugs, citrate being added to one of them in order to suppress the W(VI) catalytic activity thus providing the kinetic discrimination. The system handles 70 samples per hour and requires 1.6 mg KI per determination. A linear response is verified up to 10 mg l −1 Mo (or W) in the injectate, and signal additivity is 98–103%. Results are precise (R.S.D. < 0.04) and in agreement with ICP-OES. Running a standard reference material (IPT-50) assessed also accuracy.
Bibliography:ObjectType-Article-1
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ISSN:0039-9140
1873-3573
DOI:10.1016/j.talanta.2005.11.042