title: Tetrazine-based chemistry for nitrite determination in a paper microfluidic device.
abstract: We present a new chemistry to determine nitrites implemented in a microfluidic paper-based analytical device (µPAD). The device is fabricated in cellulose paper with a sample reception area and three replicate detection areas with recognition chemistry immobilized by adsorption. The method involves the use of nitrite in an acid medium reaction to generate nitrous acid, which produces the oxidation of s-dihydrotetrazine: 1,2-dihydro-3,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazine (DHBPTz), which change the detection zone from colorless to pink. We used a digital camera and smartphone for the quantitative analysis of nitrite with the color coordinate S of the HSV color space as the analytical parameter. Parameters such as concentration and volume of s-dihydrotetrazine, pH, sample volume and reaction time were studied. The detection limit for this method is 1.30µM nitrite. To estimate the selectivity of the method an interference study of common ions in water samples was performed. The procedure was applied to natural water and compared with reference procedures.
authors: Department of Analytical Chemistry, Campus Fuentenueva, Faculty of Sciences, University of Granada, 18071, Spain.
authors: Inmaculada
authors: I
authors: Ortiz-Gomez
authors: Department of Organic Chemistry, Campus Fuentenueva, Faculty of Sciences, University of Granada, 18071, Spain.
authors: Mariano
authors: M
authors: Ortega-Muñoz
authors: Department of Analytical Chemistry, Campus Fuentenueva, Faculty of Sciences, University of Granada, 18071, Spain.
authors: Alfonso
authors: A
authors: Salinas-Castillo
authors: Department of Information Technology, Cañada de San Urbano, University of Almería, 04120, Spain.
authors: José Antonio
authors: JA
authors: Álvarez-Bermejo
authors: Department of Analytical Chemistry, Campus Fuentenueva, Faculty of Sciences, University of Granada, 18071, Spain.
authors: Maria
authors: M
authors: Ariza-Avidad
authors: Department of Analytical Chemistry, Campus Fuentenueva, Faculty of Sciences, University of Granada, 18071, Spain.
authors: Ignacio
authors: I
authors: de Orbe-Payá
authors: Department of Organic Chemistry, Campus Fuentenueva, Faculty of Sciences, University of Granada, 18071, Spain.
authors: Francisco
authors: F
authors: Santoyo-Gonzalez
authors: Department of Analytical Chemistry, Campus Fuentenueva, Faculty of Sciences, University of Granada, 18071, Spain. Electronic address: lcapitan@ugr.es.
authors: Luis Fermin
authors: LF
authors: Capitan-Vallvey
keywords: Colorimetric assay; Microfluidic paper-based device; Nitrite determination; Photographic camera and smartphone; Tetrazine