The lifespan of ink before it fades significantly varies greatly depending on the type of ink, the material on which it's applied, exposure to environmental factors, and whether it's stored properly. For example, high-quality archival inks can last 100 years or more without noticeable fading, especially if kept out of direct sunlight and in stable, low-humidity environments. Standard inks used for everyday writing and printing may begin to fade within 5-15 years, more rapidly if regularly exposed to harsh light, heat, or moisture. UV light is particularly detrimental to ink longevity. Consequently, the general range for ink fading is from a few years to over a century, guided largely by the specific circumstances of its storage and use.

Guanidine is not classified as an amino acid but rather as an organic compound with the formula HNC(NH2)2. It is known for its role as a strong base and presence in various biological molecules. While it shares similarities with amino acids, such as containing nitrogen and being integral to biological processes, guanidine itself does not possess the carboxyl and amino groups found in amino acids. Instead, guanidine is found within the side chain of arginine, an amino acid, indicating its involvement in biochemical functions without being an amino acid itself. Its strong basicity and structural importance underline its distinctiveness from amino acids, while highlighting its relevance in biological chemistry and research.

Depending on purity and supplier. titanium prices usually range from $0.20 to $1.50 per gram.