Formic acid (purity 98–100% for analysis), pipecolic acid (purity 98%), and the methanol for LC eluent (purityP99.9%, Fluka-Analytical) were purchased from Sigma–Aldrich Co.
Formic acid (purity98–100% for analysis), pipecolic acid (purity 98%), and the methanolfor LC eluent (purityP99.9%, Fluka-Analytical) werepurchased from Sigma–Aldrich Co.