The dissolution of the synthesized samples was carried out by a modified method proposed by Horvarth-Bordon et al. 1.0 g of the Y-CNx or R-CNx samples was suspended in 50 mL of 1M aqueous KOH solution and transferred into a Teflon-lined stainless steel autoclave with a total volume of 100 mL. The autoclaves were heated at 100 °C for 16 h, then the obtained solution was filtered first through a paper filter and then through a 0.25 m PTFE syringe filter. Tri-potassium cyamelurate crystals were produced from the above-mentioned solutions by evaporation and precipitation. The needle shaped tri-potassium cyamelurate crystals formed in both cases were filtered, washed with ethanol and dried. In order to analyse the presence of minor products of dissolution in KOH of Y-CNx (Y-CNx-K) and R-CNx (R-CNx-K), the solutions were subjected to several cycles of evaporation, tri-potassium cyamelurate crystals separation and subsequent concentration of the supernatant. The supernatant was subsequently analyzed. The solid crystalline powder was obtained from the R-CNx-K solution (R-CNx-KS) by slow evaporation of water from the R-CNx-K solution, then it was washed with deionized water and dried overnight at 70 °C.