TY - JOUR
T1 - Development of a sequential injection system for the determination of nitrite and nitrate in waters with different salinity
T2 - application to estuaries in NW Portugal
AU - Mesquita, Raquel Beatriz Ribeiro
AU - Ferreira, Maria Teresa Soares Oliveira Barbosa
AU - Segundo, Ricardo Luiz Alves
AU - Teixeira, Catarina Fernanda Carvalho Pinheiro
AU - Bordalo, Adriano Agostinho
AU - Rangel, António Osmaro Santos Silva
PY - 2009/12/1
Y1 - 2009/12/1
N2 - In this work, a sequential injection methodology for monitoring nitrite and nitrate in estuarine waters without any previous treatment is described. The developed system was applied to the measurement of nitrite and nitrate in estuarine waters of three rivers in the NW Portugal, allowing an automatic, fast (ca 60 h-1) and precise method (relative standard deviation lower than 2%). The procedure was based on the reaction between nitrite, sulfanilamide and N-(1-naphthyl)-ethylenediamine dihydrochloride (N1NED), whereas the determination of nitrate resulted from its reduction to nitrite, using an in-line cadmium column, followed by the same reaction. The samples were collected in three locations for each river (Douro, Cávado and Ave) covering the lower, middle and upper section of the estuaries. Despite the presence of a salinity gradient, this parameter showed no interference in the accuracy of the determinations. The results obtained for the described method for nitrite were statistically comparable to those obtained by the reference procedure. For the determination of nitrate, recovery tests confirmed that the sequential injection methodology provided good quality results.
AB - In this work, a sequential injection methodology for monitoring nitrite and nitrate in estuarine waters without any previous treatment is described. The developed system was applied to the measurement of nitrite and nitrate in estuarine waters of three rivers in the NW Portugal, allowing an automatic, fast (ca 60 h-1) and precise method (relative standard deviation lower than 2%). The procedure was based on the reaction between nitrite, sulfanilamide and N-(1-naphthyl)-ethylenediamine dihydrochloride (N1NED), whereas the determination of nitrate resulted from its reduction to nitrite, using an in-line cadmium column, followed by the same reaction. The samples were collected in three locations for each river (Douro, Cávado and Ave) covering the lower, middle and upper section of the estuaries. Despite the presence of a salinity gradient, this parameter showed no interference in the accuracy of the determinations. The results obtained for the described method for nitrite were statistically comparable to those obtained by the reference procedure. For the determination of nitrate, recovery tests confirmed that the sequential injection methodology provided good quality results.
UR - http://www.scopus.com/inward/record.url?scp=77953679012&partnerID=8YFLogxK
U2 - 10.1039/b9ay00101h
DO - 10.1039/b9ay00101h
M3 - Article
AN - SCOPUS:77953679012
VL - 1
SP - 195
EP - 202
JO - Analytical Methods
JF - Analytical Methods
SN - 1759-9660
IS - 3
ER -