I may not be understanding your question. but the expected amount of layered double hydroxide can be calculated according the general formula M(II)(1-X)M(III)(X)(OH)2(Anion)(X/anions charge). throught coprecipitation, in my case, acording to the usel metal concentration the resulting weight show agreement with was was expected. small deviations can be usually explained due Al redisolution (if you are using Al as M(III)) or the formation of isolated phases like Al(OH)3 wich can be detected through DRX