To the Editor.—
Because of a research project, we recently reviewed the article by Ljunggren1 in the October 1990 issue of the Archives. Our recalculations showed a psoralen concentration in celery root that was 50% lower than that reported in the article. According to Ljunggren's method, a 10-g portion of celery root was homogenized and extracted. The extracted material was again dissolved in 5 mL of acetone. The concentration of psoralen in this solution was then determined to be 0.01%. Therefore, there was a total of 0.5 mg (and not 1 mg) of psoralen in the 5-mL acetone solution and, consequently, in the 10 g of celery root from which the psoralen was extracted. As a result, the 450 g of celery root that was eaten by the patient contained 22.5 mg of psoralen instead of the reported 45 mg of psoralen.Since this very original article will likely
Dijkstra JWE, Chang L. Severe Phototoxic Burn Following Celery Ingestion. Arch Dermatol. 1992;128(9):1277. doi:10.1001/archderm.1992.01680190137023
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