International Journal of Research and Scientific Innovation (IJRSI) |Volume III, Issue VIII, August 2016|ISSN 2321–2705 www.rsisinternational.org Page 30 The Complexation of Glycoside Surfactants with Divalent Metal Ions: An Electrospray Ionization Mass Spectrometric Study Khaled Edbey 1 , Grainne Moran 2 , Gary Willett 2 1 Department of Chemistry, Faculty of Science, University of Garyounis, Benghazi-Libya 2 Department of Chemistry, Faculty of Science, University of New South Wales, Sydney, Australia Abstract: -The analytical potential of the complexation of non ionic surfactants such as 1-octyl-β-D-glucopyranoside and Tween-20 with Zn(II), Cd(II), and Cu(II) was investigated by positive-ion electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. The most favorable M(II)/ 1-octyl-β-D-glucopyranoside association involves the metal attached to the deprotonated hydroxymethyl group and the hemiacetal oxygen. The binding efficiencies for 1- octyl-β-D-glucopyranoside and Tween-20 with Zn(II), Cd(II), and Cu(II) are studied.The metal binding order for 1-octyl-β-1- octyl-β-D-glucopyranosideis Cu(II) > Zn(II) > Cd(II). Keywords: glycosides, surfactants, heavy metals, mass spectrometry, environment. I. INTRODUCTION n the environment, the toxicity and bioavailability of metals are governed by the ability of natural organic molecules to bind metal ions. Among these molecules carbohydrates and carbohydrate derivatives are the most abundant biomolecules in nature. These macromolecules may be easily converted to a large variety of oligo and monosaccharides, which in turn, may complex metal ions due to their numerous hydroxyl groups. 1 Glycoside Surfactants, in particular polysorbates, are commonly utilized excipients in the pharmaceutical industry. Polysorbates are classified as nonionic surfactants and have wide range of applications in formulations. They may be utilized as wetting, emulsifiers, or solubilizers. 2-5 Mass spectrometry has become an important analytical technique for Glycoside Surfactants, particularly when small quantities are involved.1-octyl-β-D-glucopyranoside (OGP) can be used as a model system and tween as a surfactant. The reactivity between glycoside and metal ions has been widely studied in solution because of the involvement of metal ion- glucopyranosides interactions in key biological processes. Several groups have also reported the gas phase mass spectrometric study of the complexation by glycosides of alkali, alkaline earth and transition metal ions. 6-10 All these studies showed that gas-phase metal ion chemistry is a powerful tool to determine the binding strengths of metal ion- glucopyranosides. ESI-FTICR mass spectrometry has been used to examine how divalent metal ions chelate to the oxygen. FTICR mass spectrometry is used to identify the reaction products of the complexation of OGP and the commercial surfactant Tween- 20 with divalent metal ions. The selectivity of OGP binding with Zn(II), Cd(II), and Cu(II) is also studied. CID on the complexes of OGP with the Zn (II) and Cu (II) reveals structural information and is used to investigate the binding strengths of the metal ions with OGP. The reactions of divalent metal ions Cd(II), Zn(II) and Cu(II) with two different glycoside surfactants OGP and Tween-20 have been studied. As OGP and Tween-20 both contain oxygen and hydroxyl groups in sugar units, it is of interest to study how the divalent metal ions complex to these organic groups. II. EXPERIMENTAL 2.1 Raw Material The surfactants 1-O-octyl-β-D-glucopyranoside and Tween 20 were purchased from Sigma (St.Louis, Mo, USA). Cadmium nitrate, copper nitrate, and zinc nitrate were obtained from Sigma-Aldrich and were used without any further purification. 2.2 Sample Preparation The metal complexes were produced by mixing solutions of the appropriate metal salt [MX 2 whereM= Cu(II), Zn(II), Cd(II)], and X= (NO 3 ) 2 , the surfactants in a methanol (HPLC grade). The mole ratio is 1:1 for the surfactant–metal salt mixture and the concentration of each component before mixing is 1.5 x 10 -4 M. The metal ions were mixed with the surfactants as nitrate, acetate or chloride salts. Data acquisition and processing together with the comparison of the experimental isotope patterns and mass values observed and the theoretical patterns for all major product ions, are performed using Xmass version 6.2 Bruker software. A Bruker BioApex-II 7T FTICR mass spectrometer with an on- and off-axis Analytica ESI spray source was used in this study. Stronger signals were observed using the off-axis configuration. I