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.

Journal: Analytica chimica acta
Published Date: Nov 19, 2018

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 hydrochloride acid. The eluted Ti solution is buffered to pH 6.0 with 1.0 mol L ammonium acetate and mixed with 1.5 mmol L 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 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 detection limit), precise (1.40% measurement RSD at 1.00 nmol L Ti) and is characterized by a linear range of 0.50-5.00 nmol L Ti. The method was applied to analysis of natural water samples collected from the Jiulongjiang Estuary, Fujian, China.

Authors

  • Sichao Feng
    College of Life Science and Oceanography, Shenzhen University, Shenzhen, 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China; Rosenstiel School of Marine and Atmospheric Science, University of Miami, Coral Gables, 33149, FL, USA.
  • Jingfeng Wu
    College of Life Science and Oceanography, Shenzhen University, Shenzhen, 518060, China; Rosenstiel School of Marine and Atmospheric Science, University of Miami, Coral Gables, 33149, FL, USA. Electronic address: jwu@rsmas.miami.edu.
  • Dongxing Yuan
    State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China; College of the Environment and Ecology, Xiamen University, Xiamen, 361102, China.
  • Yongming Huang
    State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China; College of the Environment and Ecology, Xiamen University, Xiamen, 361102, China.
  • Kunning Lin
    State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China; College of the Environment and Ecology, Xiamen University, Xiamen, 361102, China.
  • Yaojin Chen
    State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China; College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361102, China.

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