This is a simple test to determine whether organic oxygen compounds are present in propylene dichloride (1,2-dichloropropane) and carbon tetrachloride in concentrations greater or less than 0.1 wt-% organic oxygen, using propylene glycol as the organic oxygen reference. Nitrogen and sulfur compounds interfere, while diaryl ethers give a false negative test. These are not serious limitations, since none of these classes of compounds is likely to be present in commercial propylene dichloride or carbon tetrachloride.