Sains Malaysiana 41(2)(2012): 213–218

Spectrophotometric Determination of Mercury with Iodide and Rhodamine B

(Penentuan Spektrofotometri untuk Merkuri dengan menggunakan Rhodamine B dan Iodida)

Au Yoong Yow Loo*, Yap Pei Lay, Muralithran G. Kutty & Sharifah Bee Abd Hamid

COMBICAT Laboratory, Nanotechnology & Catalysis Research Centre (NANOCEN)

University of Malaya, 50603 Lembah Pantai, Kuala Lumpur, Malaysia

Received: 18 March 2011 / Accepted: 19 August 2011

ABSTRACT

Spectrophotometric methods for the trace amount determination of Hg(II) via extraction and polyvinylalcohol (PVAl) water stabilization was explored. The methods are based on the formation of ion-association complex of Hg(II) with Rhodamine B, [(HgI4)2-][(Rhodamine B)+]2 in highly acidic solution. Extraction using benzene showed the Beer’s law was obeyed for mercury(II) in the range of 5 to 27 μg Hg(II) / 20 mL of sample and molar absorptivity, ε = 17.68 × 104 L mole-1cm-1. For polyvinylalcohol (PVAl) stabilization method, Beer’s law showed the validity range of 10 to 120 μg Hg(II) / 10 mL of sample and molar absorptivity, ε = 16.84 × 103 L mole-1cm-1. The benzene-extraction method has been applied in assessing the performance of copper sulfide ion-exchanger in removing Hg(II). The result was comparable to the result obtained using cold vapor atomic absorption spectrometry (CVAAS).

Keywords: Aqueous mercury analysis; Hg complexation; Rhodamine B; UV-Visible spectrophotometry

ABSTRAK

Kaedah spektrofotometri untuk menentukan Hg(II) melalui pengekstrakan dan penstabilan di dalam air dengan menggunakan polivinilalkohol (PVAl) telah dikaji. Kaedah tersebut berdasarkan pada pembentukan kompleks gabungan ion Hg(II) dengan Rhodamine B, [(HgI4)2-][(Rhodamine B)+]2 dalam larutan berasid. Pengekstrakan dengan menggunakan benzen mematuhi hukum Beer dalam lingkungan Hg(II) antara 5 hingga 27 μg Hg(II) / 20 mL sampel dengan pemalar serapan, ε = 17.68 × 104 l moL-1cm-1. Untuk kaedah penyetabilan dengan meggunakan polivinilalkohol (PVAl), hukum Beer's menunjukkan julat kesahihan antara 10 hingga 120 μg Hg(II) / 10 mL sampel dengan pemalar serapan, ε = 16.84 × 103 L mol-1cm-1. Kaedah pengekstrakan menggunakan benzen telah dilakukan untuk mengkaji prestasi penukar ion kuprum sulfida untuk mengekstrak Hg(II). Keputusannya adalah setanding dengan keputusan yang diperoleh menggunakan spektrometri serapan atom wap sejuk (CVAAS).

Kata kunci: Analisis merkuri akueus; Hg pengkompleksan; Rhodamine B; UV-Visible spektrofotometri

REFERENCES

Elderfield, R.C. 1950. Heterocyclic Compounds: Polycyclic Five- and Six-membered Compounds Containing One O or S Atom. Vol. 2. New York: Wiley.

Gahlmann, A., Kester, K.D. & Mayer, S.G. 2005. Investigating the effect of the zwitterion/lactone equilibrium of Rhodamine B on the cybotactic region of the acetonitrile/scCO₂ cosolvent. J. Phys. Chem. A 109: 1753-1757.

Golkowska, A. & Pszonicki, L. 1973. A study of the composition and properties of the ion-association complex of Rhodamine B with silicomolybdic acid, with a view to its analytical application. Talanta 20: 749-754.

Hasanin, T.H.A., Tsukahara, S. & Fujiwara, T. 2010. Acid-base behavior of Rhodamine B in a reversed micellar medium of cetyltrimethylammonium chloride in 1-hexanol-cyclohexane/water. Anal. Sci. 26: 1247-1254.

Hasegawa, Y., Inagake, T., Karasawa, Y. & Fujita, A. 1983. Spectrophotometric determination of gallium (III) after solvent extraction of its chloro-complex with Rhodamine B. Talanta 30: 721-723.

Hernandez-Córdoba, M., López-Garcia, I. & Sánchez-Pedreño, C. 1984. Spectrophotometric determination of mercury with thiocyanate and Rhodamine B. Microchim. Acta 84: 467-475.

Hosseini, M.S. & Naseri, Y. 2003. Determination of thallium(I) by flotation-spectrophotometric method using iodide and Rhodamine B. Anal. Sci. 19: 1505-1508.

Lopez-Garcia, I., Martinez-Aviles, J. & Hernandez-Cordoba, M. 1986. Determination of palladium with thiocyanate and Rhodamine B by a solvent-extraction method. Talanta 33: 411-414.

Marczenko, Z. & Balcerzak, M. 2000. Separation, Preconcentration, and Spectrophotometry in Inorganic Analysis. Amsterdam: Elsevier Science B.V.

Moeken, H.H.P. & Van-Neste, W.A.H. 1967. Absorptiometric determination of microgram amounts of uranium with Rhodamine B. Anal. Chim. Acta 37: 480-483.

Moreno-Villoslada, I., Jofre, M., Miranda, V., Gonzalez, R., Sotelo, T., Hess, S. & Rivas, B.L. 2006. pH dependence of the interaction between Rhodamine B and the water-soluble poly(sodium 4-styrenesulfonate). J. Phys. Chem. B 110: 11809-11812.

Phillips, H.O. & Kraus, K.A. 1965. Adsorption on inorganic materials : VI. Reaction of insoluble sulfides with metal ions in aqueous media. J. Chromatogr., A 17: 549-557.

Ramakrishna, T.V., Aravamudan, G. & Vijayakumar, M. 1976. Spectrophotometric determination of mercury(II) as the ternary complex with Rhodamine 6G and iodide. Anal. Chim. Acta 84: 369-375.

Ramette, R.W. & Sandell, E.B. 1956. Rhodamine B equilibria. J. Am. Chem. Soc. 78: 4872-4878.

Wu, C.-C. & Yang, M.-H. 1976. The retention behavior of radionuclides on copper(II) sulfide. Anal. Chim. Acta 84: 335-345.

*Corresponding author; email: yowloo@yahoo.com