Z-L-ASPARTIC ACID Β-TERT·BUTYL

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

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

Determination of Sulfur Amino Acids, Glutathione, and Related Aminothiols in Biological Samples by Gas Chromatography with Flame Photometric Detection

and lack sensitivity. GC methods based on the conversion into trimethylsilyl (4 ,5 ), neopentylidine (6 ), and N-trifluoroacetyl n -butyl ester (7 ) derivatives lack sensitivity, gives a tailing peak and requires anhydrous derivatization conditions