Direct determination of nitrite traces in high ionic-strength samples by electrostatic ion chromatography using diluted acid solutions as eluent

• Published in: Fresenius' journal of analytical chemistry 2001-12, Vol.371 (8), p.1109-1112
• Main Authors: WENZHI HU, HASEBE, Kiyoshi, DING, Ming-Yu, TANAKA, Kazuhiko
• Format: Article
• Language: English
• Subjects: Acids - chemistry; Analytical chemistry; Bromides - analysis; Chemistry; Chromatographic methods and physical methods associated with chromatography; Chromatography, High Pressure Liquid - methods; Exact sciences and technology; Nitrates - analysis; Nitrites - analysis; Osmolar Concentration; Other chromatographic methods; Seawater - chemistry; Solutions - chemistry; Static Electricity
• ISSN: 0937-0633; 1432-1130
• DOI: 10.1007/s002160101092

An ion-chromatographic (IC) system with high selectivity for separation of nitrite is described. It is analogous to the EIC (electrostatic IC) previously reported and was established using 3-(N,N-dimethylstearylammonio)propanesulfonate (C₂₃H₄₉NO₃S, a sulfobetaine type of zwitterionic surfactants) as the stationary phase and dilute aqueous HCl solutions as the mobile phase. Five inorganic anions, sulfate, chloride, bromide, nitrate, and nitrite were chosen as the model analytes and were analyzed using this EIC system. Sulfate was always eluted first, followed by chloride, bromide and nitrate. Nitrite, however, could be eluted either before or after nitrate, depending on the concentration of HCl in the eluent. An elution order nitrate3 mmol L–¹HCl as the eluent. For nitrite the detection limit was better than 2.1×10–⁷ mol L–¹ (100 µL sample injection volume, S/N=3, UV at 210 nm). Bromide and nitrate could also be separated under these HPLC conditions. The detection limit for bromide was 7.2×10–⁸ mol L–¹ and for nitrate 6.5×10–⁸ mol L–¹. Both nitrite and nitrate in real seawater samples were successfully determined with direct sample injection using this EIC system.