Pharma, Food & Specialty Chemicals

Both are the same acid. Citric acid monohydrate (C6H8O7·H2O) holds one molecule of water of crystallisation, about 8.6% by weight, while citric acid anhydrous (C6H8O7) holds essentially none, so about 1.09 kg of monohydrate supplies the acid in 1 kg of anhydrous. Anhydrous is preferred in dry mixes, powdered drinks and effervescent tablets, where moisture causes caking or premature reaction; monohydrate suits beverages and syrups.

Both work mainly in their undissociated acid form, so product pH decides. Sodium benzoate is most effective in clearly acidic products, roughly pH 2.5 to 4, such as soft drinks, pickles and sauces. Potassium sorbate remains useful up to about pH 6 to 6.5 and is used against moulds and yeasts in cheese, bakery fillings, syrups and wines. The two are often combined. In India, permitted foods and maximum levels are set by FSSAI regulations.

Both release propionic acid, which inhibits moulds and rope-forming bacteria in baked goods. Calcium propionate has little effect on yeast, so it is the usual choice for yeast-raised bread and rolls. In chemically leavened cakes, its calcium interferes with the action of baking powder, so sodium propionate is preferred there. Both salts are also used as mould inhibitors in animal feed.

Both are povidone (polyvinylpyrrolidone); the K-value expresses relative molecular weight, derived from solution viscosity. PVP K30 has lower molecular weight and viscosity, dissolves quickly and is widely used as a wet-granulation tablet binder, solubiliser and film former. PVP K90 has a much higher molecular weight, giving stronger binding and thickening at lower addition levels, and is used in demanding granulations, as a stabiliser and in hair styling products.

CMH, 3-(carbamoylmethyl)-5-methylhexanoic acid, is the racemic intermediate in a widely used pregabalin route. It is resolved to its (R)-enantiomer, RCMH, which is converted to pregabalin, the (S)-amino acid, by Hofmann rearrangement of the amide group. Buyers usually specify assay, chiral purity and related substances, so we confirm the specification and documents for each requirement before quoting.

Ferrous fumarate contains about 33% iron and is a common choice for tablets and capsules. Ferrous ascorbate combines iron with vitamin C, which aids iron absorption, and is used in anaemia tablets, syrups and supplements. Ferric ammonium citrate is water-soluble and suits tonic syrups and fortified foods. The right choice depends on dosage form, taste, iron load and the standard your product must meet.