“…Consequently, it is important to monitor the concentrations of the 6-MP frequently and hence, the methods of analysis should be not only suitable for purpose, but also be inexpensive and easy to apply. At present, there are several methods of analysis of 6-MP, e.g., traditional fluorescence (FL) (Wang and Zhang, 2008), chemiluminescence (CL), (Yang et al, 2008), electrochemical (EC) (Sato et al, 2005;Lu et al, 2008), high performance liquid chromatography (HPLC) (Su et al, 1999), and fluorescence analysis based on quantum dots (Chen et al, 2013;Gao et al, 2013). However, these methods have some limitations including, e.g., reagents, time-consuming processes, relatively low sensitivity, and poor selectivity.…”