Cancer de la vessie – comptes rendus ACP des pièces d’exérèse pour carcinome invasif de vessie. Bilan d’une évaluation de l’AFAQAP sur 26 structures en 2011

During manufacturing processes and in the storage period of tea, amino acids may undergo enantiomeric isomerization, converting their l- to d-forms. To examine the hypothesis, a method was developed for the analysis of the enantiomers in tea leaves. After enriched by ion-exchange solid-phase extraction, the enantiomeric pairs were separated by a chiral high performance liquid chromatography (HPLC) and subsequently detected and identified by using a high resolution quadrupole time-of-flight mass spectrometry (QTOF MS). Only l-forms of amino acids were found in fresh tea leaves. A total of 11 d-amino acids were found in 19 tea samples, ranging from trace amount to 43 µg/g. The results indicated that the enantioisomerization of amino acids occurred in post-harvest tea leaves, and affected by process conditions and storage time.