Simultaneous determination of titanium and molybdenum in natural waters by catalytic cathodic stripping voltammetry

✍ Scribed by Kunihiko Yokoi; Constant M.G. van den Berg

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 578 KB
• Volume: 257
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(92)85182-6

✦ Synopsis

A procedure 1s set out by which t&umun and molybdenum can be detenmned simultaneously m freshwater using cathodtc stnppmg voltammetry preceded by adsorpttve collectton of then complexes wtth mandehc acrd The ~lt~rnet~c procedure to dete~e molybdenum m natural waters IS optmuzed The optunal sohrtton ~rn~s~tmn mcludes 4 mM mandeltc actd, 45 mM chlorate, and a pH of 19 The reactton IS characterized by a peak at -0 48 V vs Ag/AgCl owmg to the electrochemrcal reductron of M(VI)-mandelate to Ma(V), the re-oxtdatlon of MO(V) by the added chlorate to Mo(VI) and the re-reductton of the thus generated Mo(VI) to MO(V) at the electrode surface Thus the reduchon current IS catalytrcally enhanced by the chlorate The hnut of detecuon of the procedure IS 14 pM with an adsorptlon trme of 60 s usmg a 10 ml ahquot of sample, thus analyttcal hmrt can be lowered further If reqmred by extendmg the depositron tune Tttanmm (peak at -0 95 V) and molybdenum can be determmed sunultaneously at pH 3 1 Measurements in lake waters reveal subnanomolar levels of these elements The data Illustrate the extraordmary sensmvny of cathodtc stnppmg voitammetry for certam smgle-electron reductron steps which can be enhanced catalyttcally