Determination of dl-amino acids, derivatized with R(−)-4-(3-isothiocyanatopyrrolidin-1-yl)-7-(N,N-dimethylaminosulfonyl)-2,1,3-benzoxadiazole, in nail of diabetic patients by UPLC–ESI-TOF-MS

Derivatization-based High-throughput Bioanalysis by LC-MS

“…Therefore, the determination using LC-MS/MS is recommended in such cases, although the derivatives are a fluorescent. [72][73][74][75][76] As an example, the analysis of the racemization and isomerization of N-terminal Asp in amyloid-β (Aβ) peptides in the brain homogenates of Alzheimer's disease (AD) patients were accomplished by (R)-DBD-PyNCS labeling and LC-MS/MS analysis ( Table 2). 77 The post-translational racemization and isomerization might induce the density and localization of plaque desposition in the brain tissue, because AD is related to the formation and aggregation of Aβ peptide plaques in the human brain.…”

Development of Benzofurazan−bearing Fluorescence Labeling Reagents for Separation and Detection in High−performance Liquid Chromatography

“…The determination of DL−amino acids in the human nail of diabetes patients (age: 40−82; 3 men and age: 58−76; 3 women) and healthy persons (age: 69−83; 3 men and age: 47−78; 2 women) was tried by UPLC−FL and UPLC−ESI−TOF−MS after derivatization with R ( )−DBD−PyNCS [78,79]. Although a long time was required for the separation of the amino acid mixture by the conventional HPLC system, the high−throughput separation is currently carried out using an ultra−high pressure HPLC system.…”

First observation of N-acetyl leucine and N-acetyl isoleucine in diabetic patient hair and quantitative analysis by UPLC–ESI–MS/MS

“…Higher concentrations of branched chain amino acids (Leu, Ile, and Val) and aromatic amino acids (Trp, Tyr and Phe) have emerged as predictors of the future development of diabetes [7][8][9][10]. In previous studies, we recently identified the N-acetyl leucine (Ac-Leu) metabolite to be a potential biomarker candidate related to diabetes.…”