Spectrophotometric flow injection determination of dissolved titanium in seawater exploiting in-line nitrilotriacetic acid resin preconcentration and a long path length liquid waveguide capillary cell

Sichao Feng, Jingfeng Wu, Dongxing Yuan, Yongming Huang, Kunning Lin, Yaojin Chen

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Abstract

A sensitive spectrophotometric method for the determination of dissolved titanium (Ti) in seawater is developed. It involves in-line preconcentration and a long path length liquid waveguide capillary cell (LWCC). Nitrilotriacetic acid (NTA) resin is used to preconcentrate Ti from ∼25 mL seawater sample at pH 1.7, and elution is accomplished with 0.8 mol L−1 hydrochloride acid. The eluted Ti solution is buffered to pH 6.0 with 1.0 mol L−1 ammonium acetate and mixed with 1.5 mmol L−1 Tiron solution. The mixture is then injected into LWCC and measured by spectrophotometry at 420 nm. Before the preconcentration step, the sample is treated with 7 mmol L−1 ascorbic acid to reduce Fe(III) to Fe(II), in order to eliminate the Fe interference. The method is not interfered by Fe(III) and Cu(II) present in seawater samples at concentrations 50-fold higher in relation to Ti, and by Cd(II), Pb(II), Cr(VI), Mn(II), Al(III), Zn(II), and Ni(II) at concentrations 100-fold higher in relation to Ti. It is time efficient (7.5 minutes per sample), sensitive (0.10 nmol L−1 detection limit), precise (1.40% measurement RSD at 1.00 nmol L−1 Ti) and is characterized by a linear range of 0.50–5.00 nmol L−1 Ti. The method was applied to analysis of natural water samples collected from the Jiulongjiang Estuary, Fujian, China.

Original languageEnglish (US)
JournalAnalytica Chimica Acta
DOIs
StateAccepted/In press - Jan 1 2018

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Keywords

  • Dissolved titanium in seawater
  • Flow analysis
  • Liquid waveguide capillary cell
  • Nitrilotriacetic acid resin
  • Spectrophotometry
  • Tiron

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Environmental Chemistry
  • Spectroscopy

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