K. Mück, S. Rotermund, F. Weiher,
T risodium citrate is an ecologically friendly, non-toxic alternative to phosphorus-based builders in automatic dishwashing detergent (ADWD) tablets. It exists in two forms: trisodium citrate dihydrate (TSC), which contains two water molecules in the crystal, and trisodium citrate anhydrous (TSA). The latter is produced by removing the water of crystallisation from the crystalline matrix, thus creating a porous structure. TSA can be loaded with liquid substances and will remain a free-flowing powder because of these pores. In the present analysis, the effects of TSC, TSA and mixtures thereof on critical tablet parameters, such as disintegration and stability, were examined. The study shows that replacing part of the TSC in the formulation with TSA decreases disintegration time and increases breaking strength after tablet pressing. This finding is supported by an existing patent (EP 3 431 575), which additionally shows that mixtures of TSA and TSC improve tablet cleaning performance. Furthermore, the present study demonstrates that the storage stability in polypropylene packaging of tablets containing TSA/TSC mixtures is comparable to that of tablets which only use TSC as the builder. Thus, TSA and TSC are not only eco-friendly builders, but can be used to modulate tablet disintegration time and stability as needed.