Talanta 72 (2007) 1088–1092 A novel Mn 2+ PVC membrane electrode based on a recently synthesized Schiff base Mohammad Hossein Mashhadizadeh a,∗ , Ehsan Pour Taheri b , Iran Sheikhshoaie b a Faculty of Chemistry, Tarbiat Moallem University, Tehran, Iran b Chemistry Department, Shahid Bahonar University of Kerman, Kerman, Iran Received 7 September 2006; received in revised form 2 January 2007; accepted 3 January 2007 Available online 18 January 2007 Abstract A new PVC membrane electrode for manganese(II) ion based on a recently synthesized Schiff base of 5-[(4-nitrophenylazo)-N- hexylamine]salicylaldimine is reported. The electrode exhibits a Nernstian response for Mn 2+ ions over a wide concentration range (4.0 × 10 −7 to 1.8 × 10 −2 mol L −1 ) with a slope of 30.1 (±1.0). The limit of detection is 1.0 × 10 −7 mol L −1 . The electrode has a fast response time (∼10 s), a satisfactory reproducibility and relatively long life time. The proposed sensor revealed good selectivities over a wide variety of other cations include hard and soft metals. This electrode could be used in a pH range of 4.5–7.5. It was used as an indicator electrode in potentiometric titration of manganese(II) ions with EDTA solution. © 2007 Elsevier B.V. All rights reserved. Keywords: Manganese(II)-selective electrode; Schiff base; PVC membrane electrode; Potentiometry 1. Introduction Manganese is a pinkish-gray and chemically active element. It is a hard and very brittle metal. Manganese is an abundant metallic element that can exist in a variety of oxidation states. Among them Mn 2+ and Mn 3+ are very important biologically. The level of manganese in drinking water ranges from 0.001 to 0.1 mg/L, but is mostly around 0.01 mg/L [1]. Manganese has low acute toxicity but neurotoxic effects have been observed in animals chronically fed high concentrations of manganese salts in the diet. High doses of manganese have also resulted in anaemia as a result of iron sequestration. Fertility is reduced by high doses of manganese but other reproductive parameters are unaffected [2]. The uptake of manganese by humans mainly takes place through food, such as spinach, tea and herbs. After absorption in the human body manganese will be transported through the blood to the liver, the kidneys, the pancreas and the endocrine glands [3]. Hence, the need for manganese ion deter- mination in clinical analysis and environmental monitoring has led to a number of methods for the measurements of this ana- ∗ Corresponding author. Fax: +98 21 88848949. E-mail address: mashhadizadeh@tmu.ac.ir (M.H. Mashhadizadeh). lyte [4–8]. Many conventional methods, such as flame atomic absorption after cloud point extraction [4], are time consuming and may require use of reagents. The use of ion-selective elec- trodes, on the other hand, is simple and can be used for in vivo measurement [9]. Even though the interest for manganese anal- ysis for various applications, such as in industrial and clinical chemistry is large, only a few reports on manganese-selective electrodes are available in literature [10–16]. Moreover, most of these electrodes have some problems, such as high detection limit, narrow working concentration range with a near- or non- Nernstian response, poor selectivity, and significant interfering cations and exhibit long response time and short lifetime. It is known that the Schiff bases derived from salicylalde- hyde (salens) polydentate ligands form very stable complexes with transition metal ions. The resulting salen complexes have attracted increasing attention, mainly due to their peculiar prop- erties and their reactivity mainly in the area of binding small molecules. However, very little is known about their complex formation equilibria in solution and also the use of salens and their complexes as carrier in ion-selective electrodes [17–20]. In recent years, we have used a variety of ligands as ion carrier in separation of some transition and heavy metal ions via solid phase extraction [21–23] and in the preparation of some new ion-selective membrane electrodes [24–27]. 0039-9140/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.talanta.2007.01.021