NMR and MS analysis of decomposition compounds produced from N-acetyl-L-glutamine at low pH.
N-Acetyl-L-glutamine decomposition products glutamine, glutamic acid, pyroglutamic acid, N-acetylglutamic acid, and a novel compound, N-(2,6-dioxo-3-piperidinyl) acetamide, have been identified by NMR and MS techniques. N-Acetylglutamine, a modified amino acid, offers greater chemical stability than glutamine in conditions that are experienced during typical sterilization and shelf storage of liquid nutritionals. However, to support safety and stability studies, potential decomposition products of N-acetyl-L-glutamine needed to be identified. Therefore, atypically harsh conditions were used; an unbuffered (pH <3) 1 mg/mL water solution of N-acetyl-L-glutamine was heated to 100 degrees C for 3 h. One-dimensional proton and proton-decoupled carbon-13 NMR and electrospray LC-MS/MS techniques were employed to identify the molecular structures of the generated N-acetyl-L-glutamine decomposition products. Additionally, DEPT and two-dimensional NMR techniques TOCSY, GMQCOSY, GHSQC, and GHMBC were employed to derive the final structure of the acetamide.
Bergana
M M
MM
Ross Products Division, Abbott Laboratories, 625 Cleveland Avenue, Columbus Ohio 43215, USA. marti.bergana@rossnutrition.com
Holton
J D
JD
Reyzer
I L
IL
Snowden
M K
MK
Baxter
J H
JH
Pound
V L
VL
D002851:Chromatography, High Pressure Liquid; D005511:Food Handling; D005973:Glutamine / Q000031:analogs & derivatives / Q000032:analysis* / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015394:Molecular Structure; D013696:Temperature; D013997:Time Factors
C032007:aceglutamide; D005973:Glutamine