CAA in the dissolved and particulate matter

Combined amino acids (CAA) in the dissolved and particulate matter 

Any of the previously described techniques for the determination of free amino acids (total, ion exchange, GC, HPLC) may be employed for estimation of CAA after a suitable hydrolysis procedure, measurement of the 

Peak identification I = cysteic acid 2 = aspartic acid 3 = glutamic acid 4 = S-carboxy-methyl cysteine 5 = asparagine 6 = serine 7 = glutamine 8 = histidine 9 = threonine fO = glycine 21= arginine 22 = 3-alanine 23 = tyrosine 24 = alanine 25 =a-amino butyric acid 26 = tryptophan 27 = methionine 28 = valine 29 = phenylalanine 20 = ammonia 22 = isoleucine 22 = leucine 23 = ornithine 24 = lysine. Chromatograms courtesy of P. Lindroth and K. Mopper. 

Whilst the conditions for the hydrolysis of protein material has been a subject of discussion in the clinical or analytical fields (see Blackburn, 1978), 

Hydrolysis with 5—6Af HCl at 100° C for 20—24 h under nitrogen (or slight modifications) appears to have been the most popular procedure. It has often been reported in the literature that hydrolysis of proteins with strong HCl results in the destructive loss of tryptophan and incomplete recoveries of methionine, threonine and serine (Blackburn, 1978). It is at present difficult to assess the extent of these losses and to evaluate the efficiency of hydrolysis when dealing with marine samples. Attempts to estimate recoveries often include the total analytical errors involved in other preconcentration desalting steps (e.g. Lee and Bada, 1975 Siezen and Mague, 1978). 

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