title: Tripodal chelating ligand-based sensor for selective determination of Zn(II) in biological and environmental samples.
abstract: Potassium hydrotris(N-tert-butyl-2-thioimidazolyl)borate [KTtt-Bu] and potassium hydrotris(3-tert-butyl-5-isopropyl-l-pyrazolyl)borate [KTpt-Bu,i-Pr] have been synthesized and evaluated as ionophores for preparation of a poly(vinyl chloride) (PVC) membrane sensor for Zn(II) ions. The effect of different plasticizers, viz. benzyl acetate (BA), dioctyl phthalate (DOP), dibutyl phthalate (DBP), tributyl phosphate (TBP), and o-nitrophenyl octyl ether (o-NPOE), and the anion excluders sodium tetraphenylborate (NaTPB), potassium tetrakis(p-chlorophenyl)borate (KTpClPB), and oleic acid (OA) were studied to improve the performance of the membrane sensor. The best performance was obtained from a sensor with a of [KTtt-Bu] membrane of composition (mg): [KTtt-Bu] (15), PVC (150), DBP (275), and NaTPB (4). This sensor had a Nernstian response (slope, 29.4+/-0.2 mV decade of activity) for Zn2+ ions over a wide concentration range (1.4x10(-7) to 1.0x10(-1) mol L(-1)) with a limit of detection of 9.5x10(-8) mol L(-1). It had a relatively fast response time (12 s) and could be used for 3 months without substantial change of the potential. The membrane sensor had very good selectivity for Zn2+ ions over a wide variety of other cations and could be used in a working pH range of 3.5-7.8. The sensor was also found to work satisfactorily in partially non-aqueous media and could be successfully used for estimation of zinc at trace levels in biological and environmental samples.
authors.affiliation: Department of Chemistry, Indian Institute of Technology-Roorkee, Roorkee, 247 667, India. akscyfcy@iitr.ernet.in
authors.forename: Ashok Kumar
authors.initials: AK
authors.lastname: Singh
authors.forename: Sameena
authors.initials: S
authors.lastname: Mehtab
authors.forename: Udai P
authors.initials: UP
authors.lastname: Singh
authors.forename: Vaibhave
authors.initials: V
authors.lastname: Aggarwal
mesh_terms: D002614:Chelating Agents; D004867:Equipment Design; D007476:Ionophores; D008024:Ligands; D008567:Membranes, Artificial; D011143:Polyvinyl Chloride; D015032:Zinc / Q000032:analysis*
chemical_list: D002614:Chelating Agents; D007476:Ionophores; D008024:Ligands; D008567:Membranes, Artificial; D011143:Polyvinyl Chloride; D015032:Zinc