An aliquot of 0.9 mL pyridine and 0.1 mL BSTFA with 1% TMS
were added to the sample extract, and incubated at 85 C for
30 min. Meanwhile, the each standard solution (0.1 mL, 0.2 mL,
0.4 mL, 0.8 mL, 1.6 mL) added with 0.5 mL internal standard solution
was also derivatized with the above method.