New PVC Nitrate-Selective Electrode:  Application to Vegetables and Mineral Waters P. Kong Thoo Lin A. N. Araujo M. C. B. S. M. Montenegro R. Pérez-Olmos 10.1021/jf049227u.s001 https://acs.figshare.com/articles/journal_contribution/New_PVC_Nitrate_Selective_Electrode_Application_to_Vegetables_and_Mineral_Waters/3303337 The paper refers the analytical potentialities of the oxa-azamacrocycles as potentiometric ionophores for the construction of electrodes selective to nitrate. Afterward, the membrane selective to nitrate is designed and optimized using a [3.3.3.3]oxazane as an ionophore. The membrane was prepared using dibutylphthalate as a solvent mediator, tetraoctylammonium as a lipophilic membrane additive, and poly(vinyl chloride (PVC) as a polymeric matrix, applied directly onto a conductive graphite/epoxy resin support. The electrodes presented a slope of 60 ± 0.1 mV log<sup>-1</sup>, a low limit of linear response of 4.2 × 10<sup>-6</sup> mol L<sup>-1</sup>, a useful lifetime of 1 year, and improved selectivity characteristics when compared with other nitrate electrodes. The good working characteristics of this electrode, constructed without inner-reference solution, made possible its application to the determination of nitrate in different types of vegetables and bottled mineral waters without the use of a conditioning solution. The application of a significant <i>F</i> test proved that the results obtained were similar to those attained by application of the brucine spectrophotometric method adopted as a reference technique. Linear regression analysis also showed good agreement between the results obtained by the proposed method and the reference one. Keywords: Oxa-azamacrocycles; ionophore; nitrate-selective electrode; vegetables; water 2005-01-26 00:00:00 nitrate electrodes selectivity characteristics conditioning solution method 1 year F test Mineral Waters mineral waters lipophilic membrane additive Linear regression analysis application reference technique potentiometric ionophores