Determination of lycopene in dietary supplements and raw materials by high-performance liquid chromatography: collaborative study.

A collaborative study was conducted to evaluate the interlaboratory performance of an LC method for lycopene in dietary supplements and the raw materials commonly used in their manufacture. Twelve laboratories from six countries agreed to participate in the study. Results from 10 laboratories were received and are reported. Five dietary supplements, including both tablets and a softgel capsule with a lycopene content ranging from 25 microg to 25 mg per unit, and three raw materials, including gelatin-based beadlets, vegetarian beadlets, and a suspension in oil ranging from 5 to 20% lycopene, were analyzed as blind duplicates. In addition to the commercial products, two positive controls and a negative control were included in the study. For the raw materials studied, the repeatability relative standard deviations (RSDr) ranged from 1.49 to 5.13% for total lycopene, and the reproducibility relative standard deviations (RSDR) ranged from 3.84 to 9.21% with HorRat values from 1.23 to 3.24. For finished products, the RSDr ranged from 1.31 to 4.62%, RSDR from 4.28 to 10.5%, and HorRat values from 0.79 to 2.07. Corresponding values for all-trans-lycopene were significantly higher. It is recommended that the method be considered for Official First Action for all-trans- and total lycopene in finished products and raw materials.