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A simple, azulene-based colorimetric probe for the detection of nitrite in water


We describe the synthesis and evaluation of an azulene-based chemodosimeter for nitrite. The probe was found to undergo two distinct color changes upon introduction of aqueous nitrite ion. A near-instant formation of a grey color provides a qualitative indication of the presence of nitrite, followed by the formation of a deep-yellow/ orange color, the endpoint from which quantitative data can be derived. The azulene probe exhibits 1:1 stoichiometry of reaction with nitrite in water, and is selective for nitrite over other anions. The azulene probe was applied to determine nitrite content in cured meat, and compared with the British Standard testing procedure (Griess test). The value obtained from the azulene-based probe agreed closely with the standard test. Our procedure only requires the preparation of one standard solution, instead of the three required for the standard Griess test.


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We are grateful for Ph.D. funding to C.M.L.-A. from the EU Horizon 2020 research and innovation programme under grant agreement H2020-MSCA-CO-FUND, #665992. The Centre for Sustainable Chemical Technologies is supported by EPSRC under grant EP/L016354/1. We also thank EPSRC for DTP Ph.D. funding to L.C.M. T.D.J. wishes to thank the Royal Society for a Wolfson Research Merit Award. NMR and MS facilities were provided through the Material and Chemical Characterisation Facility (MC2) at the University of Bath.

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Correspondence to Jannis Wenk or Tony D. James or Simon E. Lewis.

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Murfin, L.C., López-Alled, C.M., Sedgwick, A.C. et al. A simple, azulene-based colorimetric probe for the detection of nitrite in water. Front. Chem. Sci. Eng. 14, 90–96 (2020).

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  • azulene
  • nitrite
  • diazoquinone