Sodium Dihydrogen Phosphate (MSP)

About This Product

Sodium dihydrogen phosphate, MSP or monosodium phosphate, has the formula NaH2PO4 and CAS number 7558-80-7, supplied anhydrous or hydrated as white crystals or powder. It results from neutralising only one of the three protons on phosphoric acid, so it retains two and dissolves to an acidic solution around pH 4.5. Its principal industrial role is as one half of a buffer pair. A buffer resists pH change because it contains both a weak acid and its conjugate base, and any acid or alkali added is consumed by one of them rather than shifting the pH. MSP supplies the acid component and DSP the base; blending the two in different ratios fixes the working pH anywhere from roughly 5 to 8, and the pair is used wherever a process must hold pH against a chemical reaction that would otherwise drive it. Beyond buffering it acts as a sequestrant for calcium and magnesium, a mild acidulant in cleaning and metal treatment, and a component of phosphate water treatment programmes. It is also used to acidify electroplating and anodising baths where a mineral acid would be too aggressive. It is used in buffer systems, boiler and cooling water treatment, metal finishing, detergents, textile processing and as an acidulant. Bio Green Chem supplies MSP to specification on assay, pH, loss on drying, water-insoluble matter, chlorides, fluoride and heavy metals.