4-(Hydroxy(thiazol-2-yl)methyl

Quantitation of Cocaine, Benzoylecgonine, Ecgonine Methyl Ester, and Cocaethylene in Urine and Blood Using Gas Chromatography-Mass Spectrometry (GC-MS

under the stream of nitrogen. The residue is incubated with pentafluoropropionic acid anhydride and pentafluoropropanol to form pentafluoropropionyl derivatives of ecgonine methyl ester and benzoylecgonine. Cocaine and cocaethylene are refractory to derivatization

Enzymes Acting on d-Amino Acid Containing Peptides

aminopeptidase and endopeptidase activities. The enzyme was active toward (d -Phe) n , Boc-(d -Phe) n , (d -Phe) n methyl ester, d -Phe-NH2 , Boc-(d -Phe) n methyl ester, and Boc-(d -Phe) n tert -butyl ester, but not toward (d -Ala) n (n = 2–4), (d

Boronate Affinity Chromatography

bond strength has not been well studied and only a few dissociation constants for phenylboronic acid diesters have been reported. Those reported include adonitol, 2.2 � 10 -3 M; dulcitol, 1.1 � 10 -3 M (4); mannitol, 3.3 � 10 -3 M ( 5 ); and NADH, 5.9 �