In a Russian document I'm translating, an HPLC system is used to analyse the amino acid content of a substance.
The detector wavelength is set at 262 nm for "secondary amino acids" and 338 nm for "primary amino acids". But what are those?
I googled and found a lot of mentions with exactly these wavelengths being used, but I haven't been able to quickly understand how a "primary" amino acid differs from a "secondary" one. Is it that the secondary amino acids are the products of the destruction of the primary amino acids (those that initially existed in the substance)?
What is the difference between a "primary amino acid" and a "secondary amino acid"?