clarification for HS code differs between purchase and sales

I am a manufacturer wherein I have purchased a product wherein HS code for my purchase and HS code for my sale differs.

During filing of returns, HS code for purchase and sales will not match then how will be the same get adjusted?

Also while filing returns, do we have to mention HS code under sales?

example
I purchase Sodium chloride and the HS code assuming it's 100.
from that Sodium chloride, I have prepared saline water solution.
HS code for saline water solution is 101.