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FID-method (for amino acids and amino acid derivatives and, if high standard deviation is acceptable, peptides)
   
This methods involves hydrolysis with 6N hydrochloric acid (for peptides), derivatization of the free amino acids and gas chromatographic separation of the enantiomers on a chiral column. 

This method is 

  • sufficient for pure amino acids 
  • mostly sufficient for for amino acid derivatives 
  • suffcicient for screening of peptides 
    This method however suffers from one weakness: under the condition of hydrolysis, racemization occurs and the amount of racemate determined represents the sum of the amount originally present in the peptide plus the generated during hydrolysis. The last is determined using a standard peptide and will be subtracted from the determined values. However the standard deviation is high due to matrix and sequence influences.
    The standard deviation is 0.3-1%; for cysteine and the amino acids which are linked at cysteine >2%.
What we need:
1mg of the sample.
Protective groups if present.
Amino acids which are to determine or for peptides the sequence.
Expected peptide content.

This analysis can be offered for

  
 Amino acids (A430)  
 Amino acid derivatives (A440)  
 Peptides (A410)
If you need reliable results <1% respectively <2% for cysteine and the amino acid which is linked on cys, peptides are to be analyzed using the GC-MS method		  
 

 

 
 
     

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