title: Microfluidic polymer chip with an embedded ion-selective electrode detector for nitrate-ion assay in environmental samples.
abstract: A nitrate ion-selective electrode (NO(3)(-)-ISE) has been developed based on tetradodecylammonium bromide as an anion exchanger and 2-nitrophenyl octyl ether as a plasticizer. The NO(3)(-)-ISE shows an almost Nernstian response to nitrate ion over a concentration range between 1.0 x 10(-6) and 1.0 x 10(-1) M, with an anionic slope of -57.7 +/- 0.7 mV/decade. The selectivity coefficients of the NO(3)(-)-ISE for nitrate ion against chloride and sulfate (log k(NO(3)(-)Cl(-))(pot) = -2.42 and log k(NO(3)(-)SO(4)(2-))(pot) = -4.33) were obtained. A microfluidic polymer chip was fabricated using polystyrene plates and stainless-steel wires as a template for the channel. The microfluidic polymer chip is composed of a mixing chip and a NO(3)(-)-ISE detector chip. The microfluidic polymer chip, integrated with a NO(3)(-)-ISE detector consisting of the NO(3)(-)-ISE and a Na(+)-ISE as a reference electrode, showed an almost Nernstian response to nitrate ion over a concentration range between 1.0 x 10(-5) and 1.0 x 10(-1) M, with an anionic slope of -54.3 +/- 1.3 mV/decade. The microfluidic polymer chip was then applied to the determination of nitrate ion in environmental water samples, such as a tap water, a well-water sample and water for agricultural use.
authors.affiliation: Department of Applied Chemistry, Faculty of Engineering, Shibaura Institute of Technology, Toyosu, Koto, Tokyo 135-8548, Japan. masadome@sic.shibaura-it.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Masadome
authors.forename: Kazuki
authors.initials: K
authors.lastname: Nakamura
authors.forename: Daisuke
authors.initials: D
authors.lastname: Iijima
authors.forename: Osamu
authors.initials: O
authors.lastname: Horiuchi
authors.forename: Benjaporn
authors.initials: B
authors.lastname: Tossanaitada
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Wakida
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Imato
mesh_terms: D000383:Agriculture; D004566:Electrodes; D004777:Environment; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D009566:Nitrates / Q000032:analysis* / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D009566:Nitrates; D011108:Polymers; D000644:Quaternary Ammonium Compounds; D014867:Water