In the Figure In , a Raman study of cysteamine monolayers on silver had been proposed. The monolayers "were spontaneously formed on silver surfaces by chemisorption from cysteamine and cystamine solutions" . In their Table , we can find data regarding solid Cysteamine, that is 758, 938, and 1012 cm -1 , and the aqueous solution, that is 510, 666, 753, 936, and 1013 cm -1 . From the Figures and As observed by Xheng et al., the total detection time of the Hcy/OPA spectrum needs "more than 2 h, and it cannot be applied to human serum clinical samples" .