Salicylaldoxime

Salicylaldoxime is a chemical compound described by the formula C6H4CH=NOH-2-OH. It is the oxime of salicylaldehyde. This crystalline solid is a chelator and sometimes used in the analysis of samples containing transition metal ions, with which it often forms brightly-coloured coordination complexes.

In the era when metals were analysed by spectrophotometry, many chelating ligands were developed that selectively formed brightly coloured complexes with particular metal ions. This methodology has been eclipsed with the introduction of inductively coupled plasma methodology. Salicylaldoxime can be used to selectively precipitate metal ions for gravimetric determination. It forms a greenish-yellow precipitate with copper at a pH of 2.6 in the presence of acetic acid. Under these conditions, this is the only metal that precipitates; at pH 3.3, nickel also precipitates. Iron (III) will interfere.

Adsorbed or chemically bonded to a solid support such as silica gel, it can be used to preconcentrate or extract metals from a dilute solution such as seawater. It has been used as an ionophore in ion selective electrodes, with good response to Pb2+ and Ni2+.

Salicylaldoxime has been used to probe ion channels in muscle tissue and as a probe in photosystem I.