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Amino acid analyses with determination of the blind values (=enantiomeric purity after hydrolysis), SOP A.0.4.):
   

With this analysis (A400) the information of the enantiomeric purity of the amino acids after hydrolysis is determined. That is necessary for quantitative calculation because the enantiomers are used as internal standard.
For determination of the optical purity before hydrolysis estimation of the proportion due to racemization during hydrolysis is possible but the standard deviation is high. In consequence reliable determination of the enantiomeric purity the peptide constituting amino acids is not possible <0.5%-1%, for Cys and amino acids linked on Cys <5% using this method.

 
Reliable quantitation of racemate with LOQ of 0.1% involves sample preparation using deuterated reagents and GC-MS analysis:
Racemization during sample preparation is accompanied by deuterium exchange in the α-position (deuterium label). Racemised molecules are not detected using suitable fragments of amino acids in GC-MS analysis (A790).

 

Substance specific validations of the methods could be offered. In this case we would issue a validation plan to determine the items of validation.

 

  
Results:
Content of amino acids (mg/g, µmol/g)
Enantiomeric purity of amino acids after hydrolysis
Residues of amino acids
Peptide content 		 
 What we need:
1.5mg of the sample (for reliable peptide content).
The theoretical amino acids composition or better the sequence.
Protective groups if present.
Molecular weight of the peptide (This molecule will be determined as peptide content).
Expected content.		  
   
 

 

 
 
     

   © 2004 by Daniel Gerhardt •  daniel.gerhardt@cat-online.com