The proposed method was applied to the analysis of melamine leached from tableware. To avoid the uncertainty caused by different surface conditions, replicate analysis was carried out by using the same tableware. Samples studied in the first protocol could be analyzed directly with no concentration process because the method was sensitive enough to analyze the trace amount of melamine in the initial extract. For samples which could not be detected by direct derivatization, concentration steps were needed. Leaching of melamine was found in all the samples analyzed by the
first approach with concentrations ranging from 4.24 to 428 mg L1 (concentration was expressed as the concentration in the extracted solution). No leaching of melamine was found in the second approach though the extracts were concentrated by 20 times. The results obtained by the two different methods were listed in Table 3, and typical chromatograms of extracted samples were shown in Fig. 2.