Response characteristics of new perchlorate selective PVC membrane electrode based on a tripodal benzimidazole derivative as a neutral carrier

The potentiometric response characteristics of a new perchlorate selective poly(vinyl chloride) membrane electrode based on a tripodal benzimidazole derivative - tris[2-(1-ethylbenzimidazolyl)]methylamine as ionophore was investigated. The electrode exhibited a Nernstian response to perchlorate ions over the activity range of 1.5 x 10(-7) to 1.0 x 10(-1) M with a limit of detection of 5.2 x 10(-8) M between pH range of 2.0-10.0, giving a relatively fast response and reversibility within 5 s. The selectivity coefficient was calculated using fixed interference method (FIM). The electrode worked well for nearly 3 months. The electrode can also be used in partially non-aqueous media having up to 25% (v/v) methanol, ethanol or acetone contents with no significant change in the value of slope or working concentration range. It was successfully applied for the direct determination of perchlorate content in water and human urine samples with satisfactory results.