Nitro-chromic test

Alcohols, glycerol, and formaldehyde invalidate the Nitro-chromic Test, as they also give a positive reaction. 

Ethyl Alcohol.— The detection of ethyl alcohol in urine may be important in the diagnosis of intoxications. Distil carefully 50-100 ml. of the urine, and apply the iodoform test and the nitro chromic test (p. 109) to 5 ml. samples of the distillate. Alcohol gives a positive reaction with both tests. Acetone, if present, will also come over in the distillate, and give a positive iodoform reaction, but does not give a blue colour with the nitro chromic reagent. 

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