Definition
A glass vial tinted to block ultraviolet and short-wavelength visible light, protecting light-sensitive contents.
Amber vials are made from glass containing iron and sulfur compounds that absorb ultraviolet and blue light, typically below about 450 nm. They protect light-sensitive compounds from photodegradation. In peptides, residues such as tryptophan, tyrosine, cysteine and methionine can undergo light-induced oxidation, and some chromophores and metal complexes, including copper peptides, may also be sensitive. Amber glass reduces this risk but does not eliminate it, so storage in the dark remains good practice. Clear vials are common for lyophilised peptides because they allow visual inspection of the cake and are generally adequate when kept in a closed freezer. Borosilicate glass is preferred for its chemical resistance.