2.1. Chemical reagents
The chemical reagents used in this study (l-lysine
monohydrochloride, pyridine, and sodium hydroxide) were obtained from
Sigma-Aldrich (USA). The derivatization reagent, ethyl chloroformate
(ECF), was purchased from Fluka (Japan). NaHCO3 was
purchased from Samchun (Korea). Methanol and chloroform were obtained
from Fisher (Korea). Triton X-100 and sodium phosphate (Monobasic and
dibasic, anhydrous) were purchased from Biosesang (Korea).