Perhaps you should try some spelling variations:
ppm decrease » a decrease (Expand Search), nn decrease (Expand Search), pa decreased (Expand Search)
ng decrease » nn decrease (Expand Search), a decrease (Expand Search), we decrease (Expand Search)
mg decrease » a decrease (Expand Search), nn decrease (Expand Search), we decrease (Expand Search)
50 ppm » 5 ppm (Expand Search)
5 ng » 5 g (Expand Search), 5 nm (Expand Search), 5 kg (Expand Search)
5 mg » 5 mm (Expand Search)

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "(((( 50 ppm decrease ) OR ( 50 _ decrease ))) OR ((( 5 ng decrease ) OR ( 5 mg decrease ))))~".
• Adding a wildcard symbol may retrieve word variants: (((( 50 ppm decrease ) OR ( 50 _ decrease ))) OR ((( 5 ng decrease ) OR ( 5 mg decrease ))))*.