Multiparametric automated system for sulfate, nitrite and nitrate monitoring in drinking water and wastewater based on sequential injection analysis

An automated monitoring system for sulfate, nitrite and nitrate based on sequential injection analysis (SIA) was developed. For nitrite determination the modified Griess-Ilosvay method was used, whereas nitrate was previously reduced to nitrite using a cadmium column followed by nitrite determination. A turbidimetric method was carried out in order to determine sulfate. The results showed that the proposed SIA monitoring system constitutes an effective approach for nitrite, nitrate and sulfate determination since it is able to determine levels required by international agencies that regulate these parameters in water. Detection limits of 0.0207 mg N L− 1, 0.0022 mg N L− 1 and 3 mg SO42− L− 1 were obtained for nitrate, nitrite and sulfate, respectively. The developed method offers also typical characteristics of the multicommutated systems, as portability, low reagents consumption and the subsequently minimization of waste generation. The proposed system was successfully applied to drinking water and wastewater samples and validated with a certified river water sample (ION-96.3, LGC Standards).