Phosphorus:
Not having a direct role in film development, it can be claimed that some compounds used in photography-related chemicals may contain phosphorus. For example, certain types of developers or toners may utilize phosphorus-based compounds to enhance specific properties or achieve desired effects, such as:
Sodium hexametaphosphate: Often referred to as Calgon
Sodium phosphate: Various forms of sodium phosphate, such as monosodium phosphate (NaH2PO4) or disodium phosphate (Na2HPO4), Phosphoric acid (H3PO4)
Phosphonium salts: Certain phosphonium salts, such as tetraphenylphosphonium bromide.
