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Phenylalanine
Tyrosine
Tryptophan
Histidine
Actually there are 10 essential amino acids of which 2 are essentially only in children. The ten essential amino acids are:-
Of these, arginine and histidine are essential only in children.
Essential amino acids Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine
In Lowry spectrophotometric assay, tryosine, tryptophan, cysteine, histidine, and asparagine.
My information lists ten - lysine, tryptophan, valine, histidine, leucine, isoleucine, phenylalanine, threonine, methionine, and arginine.