Material Quantity Calculation

Hi Experts,

While working on Material Quantity Calculation which is done on the basis of purity of API (BOM component). The material quantity should be based on the purity which can vary from 98 - 102%. Now the requirement is if BOM component purity is above 100% it should be considered as 100% only while material quantity calculation. Can we restrict this in any way using object dependencies or function modules.

Regards

Neelima