ABSTRACT
An analytical methodology based on an O-[2-(methacryloyloxy)-ethylcarbamoyl]-10,11-dihydroquinidine (MQD)-silica hybrid monolithic column was developed for the enantioseparation of 9-fluorenylmethoxycarbonyl (FMOC) derivatized amino acids by nano-liquid chromatography. The mo-bile phase was optimized including the apparent pH, content of ACN, and concentration of the buffer to obtain a satisfactory enantioresolution performance. 27 FMOC derivatized amino acids including 19 protein and 8 non-protein amino acids were tested, and 19 out of them were enantiomerically discriminated obtaining baseline separation for 11 of them. Analytical characteristics of the method were evaluated for norvaline and tryptophan in terms of linearity, precision, accuracy, limits of detection (LOD) and quantitation (LOQ) showing good performance to be applied to the enantiomeric determination of these amino acids in dietary supplements. LOD and LOQ values were 9.3 and 31μM for norvaline en-antiomers and 7.5 and 25μM for tryptophan enantiomers, respectively. The contents of D-norvaline and D-tryptophan were below their respective LODs in all the analyzed samples. Quantitation of L-tryptophan and L-norvaline showed good agreement with the labeled contents except for one sample which did not show presence of L-norvaline, contrary to the label indication.
ABSTRACT
Objective: To search for a new method for synthesis of 9 fluorenylmethoxycarbonyl amino acid tert-butyl ester. Methods: Glycine, L-Proline, and L-Phenylanaline were separately allowed to react with 9-fluorenylnmthylchloroformate to obtain the corresponding 9-fluorenylmethoxycarbonyl amino acids. With 4-(dimethylamine) pyridine (DMAP) used as catalyst, the 9-fluorenylmethoxycarbonyl amino acids were allowed to react with Tert butyl dicarbonate for the corresponding 9-fluorenylmethoxycarbonyl amino acid tert-butyl esters. Results: Three 9-fluorenylmethoxycarbonyI amino acid tert-butyl esters were successfully synthesized by this method and their structures were confirmed by 1 H NMR. Conclusion: Ours is a simple method with mild condition and high yielding rate for synthesis of 9-fluorenylmethoxycarbonyl amino acid tert-butyl esters.