Note that the observed ion species could also be generated upon electron ionization. However, mass spectrometry using innert buffer gas detected [TCNE] •-(a molecular mass of 128.09 g/mol) as the major adduct anion , but no 1,1,2,3,3,-pentacyanopropenide [C 3 (CN) 5 ] -(a molecular mass of 166.12 g/mol). This suggests that 1,1,2,3,3,-pentacyanopropenide was present in the measured THF solution of TCNE and the aqueous THF solution of TCNE and melamine. As water is in the mobile phase of the HPLC-MS system, TCNE should have reacted with water to yield 1,1,2,3,3,-pentacyanopropenide. The main UV-Vis absorption features observed for both aqueous THF solution of TCNE and aqueous THF solution of TCNE and melamine (Fig. and) should therefore correspond to 1,1,2,3,3,-pentacyanopropenide. Hence, 1,1,2,3,3,-pentacyanopropenide is likely the species that is embeded in the melamine crystals. For all solutions, no dependency on the concentration is observed. The spectra for the THF solutions of TCNE exhibit the intense doublet in the UV range with a sharp upper wavelength edge at 280 nm. The less intense absorption peaks are observed at longer wavelengths According to mass spectroscopy, TCNE reacts with water to yield 1,1,2,3,3,-pentacyanopropenide in a mixture of THF and water. Accordingly, the UV-Vis absorption spectra for the aqueous solutions of TCNE differ entirely from those for the THF solutions of TCNE. They exhibit two distinct absorption features, as shown in Fig. . The first peak is located at about 298 nm. The second one is the multiplet located in the wavelength range between 350 and 450 nm.