JOURNAL OF COSMETIC SCIENCE 150 MEASUREMENT OF THE LOWEST QUANTITATIVELY DETERMINABLE CONCENTRATION OF SAFROLE The stock safrole standard solution (1,000 μg/ml) was serially diluted to 50, 25, 10, 5, 2.5, and 1 μg/ml. Following addition of DA IS solution (1 mg each), the diluted standard solution containing DA was directly injected into the gas chromatograph equipped with an FID under the conditions described in the Materials and Methods section, with settings of FID range = 2 and attenuation = 2. Under these conditions, the results showed that when the CV% for safrole recovery was set at 15%, the lowest quantitatively determinable concentration of α-terpineol was approximately 5 μg/ml (Table II). RECOVERY RATES IN SAMPLES FORTIFIED WITH SAFROLE When 2 or 10 mg of safrole were added to 1 g of Stout Camphor essential oil prepared in our laboratory, the recoveries of safrole from the samples were 97.6 to 101.5%, with a CV% of 5.6% or lower (Table III). When 1 or 10 mg of safrole were added to 1 g of the upper layer of Small-fl ower Camphor essential oil, the recoveries of safrole from the sam- ples were 96.1 to 103.5%, with a CV% of 4.2 or lower (Table III). The results indicated that with high or low safrole contents in the essential oil samples, the recovery rates were not only high, but also accurate using our quantitative method. Figure 2. Gas ch romatogram of (A) Stout Camphor essential oil (extracted with ether from C. kanehirai Hayata) and (B) commercial Stout Camphor essential oil. Peak 1 = DA Peak 2 = safrole.

DETERMINATE SAFROLE IN COMMERCIAL ESSENTIAL OILS 151 COMPARISON OF OUR METHOD TO THE AOAC METHOD To examine the accuracy of the proposed method for safrole measurement, safrole contents in the oil samples were measured by the AOAC method and by our method. With the AOAC method, the safrole levels in a Stout Camphor essential oil sample (S1) and a natural Figure 4. Calibrat ion curve of safrole to DA. Figure 3. Gas chr omatogram of (A) Small-fl ower Camphor (C. kanehirai Hayata) essential oil (upper layer) and (B) Small-fl ower Camphor essential oil (lower layer). Peak 1 = DA Peak 2 = safrole.