小中大腐殖酸是混合物,你直接拿买回来的试剂是无法全部溶解的。第一天的时候不是溶解,只是形成了小颗粒的悬浮物,第二天还是会沉降下来的。所以你需要纯化一下。A known amount of unpurified HA was dissolved in 0.1 M NaOH and then filtered. The solution was acidified to pH 1.0 using concentrated HCl solution and filtered. The precipitates were washed with 0.1 M HCl for three times and lyophilized. 简单说来,就是先用碱溶解,过滤,再用酸沉淀,再把沉淀洗净冻干。用的时候取一定量溶解。关于腐殖质的性质,你可以看腐殖质化学这本书,你就知道腐殖质,富里酸,胡敏酸是怎么定义的了。溶解性是和pH有关的,另外也会受到离子强度和离子种类的影响,你自己考虑好,先查些文献看看吧,腐殖酸是一个很广泛的研究课题。