A procedure for the determination of orthophosphate and condensed phos
phates in castables is proposed. The sample is calcined with sodium ca
rbonate and leached with deionized water. After removing the interferi
ng components from the matrix by cation-exchange, the sample solution
is subjected to ion-chromatographic determination with gradient elutio
n and conductivity detection. Recoveries are within 84-89% with a rela
tive standard deviation of less than 3.6%.