Analysis of NO and its metabolites by mass spectrometry. Comment on ‘Detection of nitric oxide in tissue samples by ESI-MS’ by Z. Shen, A. Webster, K. J. Welham, C. E. Dyer, J. Greenman and S. J. Haswell

Abstract

Recently, Shen et al. (Analyst, 2010, 135, 302) reported on a flow injection analysis (FIA) ESI-MS/MS approach for the determination of the short-lived gaseous nitric oxide (NO) in biological samples. This method is based on the reaction of NO, and presumably of other NO-derived oxides such as N₂O₃, with the vicinal amino groups of methylpiperazinobenzendiamine to form a benzotriazole derivative. Under MS/MS conditions, the protonated derivative loses molecular nitrogen (N₂) from the triazole ring and the product ion formed is utilized for quantitative analyses. This seems to be the first ESI-MS/MS method for authentic NO detection and quantification. However, the ESI-MS/MS method reported by Shen et al. deserves some critical discussion.