Analytical Sciences

Rapid Method for Simultaneous Determination of Nitrite and Nitrate in Water Samples Using Short-Column Ion-Pair Chromatographic Separation, Photochemical Reaction, and Chemiluminescence Detection

Hitoshi KODAMATANI,*1 Shigeo YAMAZAKI,*2 Keiitsu SAITO,*3 Yu KOMATSU,*4 and Takashi TOMIYASU*1

*1 Graduate School of Science and Engineering, Kagoshima University, 1-21-35 Korimoto, Kagoshima 890-0065, Japan
*2 Department of Applied Science, Okayama University of Science, 1-1 Ridaicho, Okayama 700-0005, Japan
*3 Division of Human Environment, Graduate School of Human Development and Environment, Kobe University, 3-11 Tsurukabuto, Nada, Kobe 657-8501, Japan
*4 Environmental Research Institute, Kanazawa Institute of Technology, 3-1 Yatsukaho, Hakusan 924-0838, Japan

A rapid method has been developed for the simultaneous determination of nitrite and nitrate. The separation of nitrite and nitrate was achieved using an octadecylsilane (ODS) short column (5 μm, 20 × 4.6 mm) with 10 mM of borate buffer–methanol (99.5:0.5, v/v; pH 10.0), containing 5 mM of lauryltrimethylammonium chloride and 50 mM of NaBr. These ions were detected by luminol chemiluminescence following online UV irradiation. The calibration curves of nitrite and nitrate were linear in the range of 1.0 × 10⁻⁷ to 2.0 × 10⁻⁵ M and 1.0 × 10⁻⁶ to 2.0 × 10⁻⁴ M, respectively. The detection limits for nitrite and nitrate were 0.05 and 0.4 μM, respectively (with a signal-to-noise ratio of 3). The precisions of peak heights for 7 identical injections of a standard mixture of 0.50 μM of nitrite and 5.0 μM of nitrate were 2.7 and 2.1%, respectively. Analysis time per sample was less than 2 min, and system pressure was low (2.1 MPa). The proposed method was successfully applied to water samples from various sources.

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