Describe briefly the following:

Downstream processing

After the industrial synthesis of the required product is complete it is obtained in crude form and requires passing through a series of processes before the product can be marketed. These processes include separation and purification of the desired product which are collectively known as the downstream processing. In some cases, especially drugs, these products have to undergo certain clinical trials. Quality control testing is strictly required and some product has to be formulated with suitable preservatives too. The downstream processing of the obtained product varies with product variety.