The metabolic fate of orally administered ¹⁴C-DNPDA containing 0.028% ¹⁴C-BNA was studied in the Rhesus monkey, and the aqueous solubility of these 2 chemicals was investigated. Monkeys were given doses of 0,10, or 100 mg/kg ¹⁴C-DNPDA via gelatin capsules. Uptake by the blood, tissue distribution, and urine and fecal elimination were monitored for up to 168 hours. In these studies ¹⁴C-BNA was 10 to 15 times more soluble than ¹⁴C-DNPDA. Very low levels of ¹⁴C-DNPDA were observed in the blood, tissues, and urine; most (65–75%) of the parent compound was recovered unchanged in the feces. The blood uptake studies showed that the ¹⁴C-BNA impurity is selectively absorbed over the ¹⁴C-DNPDA. Although it was not possible to completely rule out the metabolic formation of ¹⁴C-BNA, the data suggested that any BNA formed via metabolism is insignificant relative to the contribution of any impurity in the product.