Merck, 32745-50G, Malachite Green oxalate salt

General description
Malachite green is manufactured as a zinc-free oxalate salt (green crystals with a metallic sheen) or as a zinc chloride salt (yellow crystals). Malachite green comes under the triphenyl methane class of dyes and is one of the most effective agents traditionally known for treating water mold infections of fish and eggs. It has also been found to be effective against ectoparasites, protozoan and some myxozoan parasites. Though it has several disadvantages like it acts as respiratory poison, teratogen and suspected carcinogen. It generated free radicals, thereby making it highly toxic to mammalian cells in culture; it also causes malignant transformation. It has a long half-life and can persist in tissues for long periods. In water, malachite green exists in equilibrium between the colored, ionic form and the colorless, nonionic pseudobase (carbinol form). Only the colored ionic form has antimicrobial activity, whereas the carbinol form is lipid-soluble, hence allowing it to pass across membranes. The toxicity of malachite green is dependent on temperature and it increase with increase in temperature, whereas it is more toxic at low pH and low hardness. It is phyotoxic in nature, thereby it is inactivated (oxidised) by light.
Application
Malachite green oxalate salt was used in studying the photocatalytic degradation with TiO₂/WO₃. It was also used in preparing selective medium for isolating Verticillium fungicola from mushroom. It may be used for the determination of phosphate in serum. It may also be used to monitor the presence of free COOH on the solid-phase. It may be used as reference materials for in an analytical method to independently quantify malachite green oxalate and leucomalachite green in fish tissue. It may also be used in Rappaport broth for incubating the membrane filters used in detecting Salmonella sp.
Other Notes
The molecular mass of malachite green oxalate is expressed as either:
927.00 g/mol - the mass of 2 mol malachite green + 2 mol monohydrogen oxalate + 1 mol dihydrogen oxalate, or
463.50 g/mol - the mass of 1 mol malachite green + 1 mol monohydrogen oxalate + 0.5 mol dihydrogen oxalate