WordNet sense 1 (mixed with impurities):

adulterate, adulterated, adulterate

WordNet sense 2 (combined with extraneous elements):

impure

WordNet sense 3 (lowered in value):

degraded, devalued

WordNet sense 4 (less than normal in degree or intensity or amount):

low

WordNet sense 5 (ruined in character or quality):

corrupted, vitiated

WordNet sense 6 (lacking in integrity):

corrupt