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November 1977

Percutaneous Penetration Following Use of Hair Dyes-Reply

Author Affiliations

San Francisco

Menlo Park, Calif

Arch Dermatol. 1977;113(11):1610. doi:10.1001/archderm.1977.01640110130029

In Reply.—  We observed in our laboratories and in others that when urine is heated at 100 C for periods of one to two hours at pH 1 and is extracted by ethyl acetate or other solvents at pH 11 and is followed by TLC, a variety of colored spots can be observed owing to hydrolysis of conjugated blood pigments. When this procedure is followed without heating at pH 1, no colored spots are observed on TLC.In our previous study, we were careful to avoid heating the urine at pH 1 or allowing the urine to stand longer than two to three hours at 20 C before extraction. In our control urine samples, taken from persons prior to hair dyeing, we never observed colored spots on TLC (eight subjects). Furthermore, a total of thirty-seven 24-hour urine samples that were taken from the subjects after they had dyed their hair

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