The sealed ampule was placed in a glass bead bed, within a 110deg. Our experience indicates that this freeze and thaw method, in general, increases the recovery of many amino acids. After hydrolysis, the ampule was opened and the sample was evaporated to dryness in a Savant Speed Vac system. This was then filtered through a 0.2 um filter and 50 u1 of the resulting amino acid solution was separated using the Beckman analyzer. Standard analysis conditions and chromatograms for the ABRF sample can be seen in Fig.
Cysteine determination tends to be a difficult and time consuming procedure.
This is due to the alternative methods that are required as a result of cysteine destruction during normal HCl hydrolysis. L-cysteine derivatized product is highly resistant to HCl destruction and is easily separated using our analyzer. After desalting the sample, the resulting solution was lyophilized and hydrolyzed as described above. Separate analyzer run conditions are required to resolve PE cysteine which coelutes with lysine under standard run conditions. Refer to Fig.