What is the solution if I bought materials containing pig derivatives after exercising diligence before purchasing, and should they be thrown in the trash?

If the food items are confirmed to contain pork derivatives with their traces remaining, then the contract is void, and it is obligatory to annul it and return the goods and the money. If that is not possible, then it is not permissible to use them; rather, they must be disposed of by destroying them. However, if the pork derivatives have transformed into a pure substance and no trace of them remains due to istihalah (chemical transformation), then it is permissible to use them.