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Updated: Feb 20, 2026

Measuring Nitrite and Nitrate, Metabolites in the Nitric Oxide Pathway, in Biological Materials using the Chemiluminescence Method
Published on: December 25, 2016
Rapid visual and spectrophotometric nitrite detection by cyclometalated ruthenium complex
Hoi-Shing Lo1, Ka-Wai Lo2, Chi-Fung Yeung3
1Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong Special Administrative Region; Shenzhen Research Institute, City University of Hong Kong, Shenzhen, 518057, PR China.
Abstract:
Quantitative determination of nitrite ion (NO2-) is of great importance in environmental and clinical investigations. A rapid visual and spectrophotometric assay for NO2- detection was developed based on a newly designed ruthenium complex, [Ru(npy)([9]aneS3)(CO)](ClO4) (denoted as RuNPY; npy = 2-(1-naphthyl)pyridine, [9]aneS3 = 1,4,7-trithiacyclononane). This complex traps NO+ produced in acidified NO2- solution, and yields observable color change within 1 min at room temperature. The assay features excellent dynamic range (1-840 μmol L-1) and high selectivity, and its limit of detection (0.39 μmol L-1) is also well below the guideline values for drinking water recommended by WHO and U.S. EPA. Practical use of this assay in tap water and human urine was successfully demonstrated. Overall, the rapidity and selectivity of this assay overcome the problems suffered by the commonly used modified Griess assays for nitrite determination.
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