High-performance liquid chromatographic analysis of 6-gingerol, 8-gingerol, 10-gingerol, and 6-shogaol in ginger-containing dietary supplements, spices, teas, and beverages.

Ginger root powder is widely used as a dietary supplement as well as a spice and flavoring agent in foods and beverages. In this study, we developed a high-performance liquid chromatographic (HPLC) method that is suitable for the analysis of 6-gingerol, 6-shogaol, 8-gingerol, and 10-gingerol in a wide variety of ginger-containing dietary supplements, spices, teas, mints, and beverages. 6-Gingerol, 6-shogaol, 8-gingerol, and 10-gingerol were extracted from various ginger-containing products with ethyl acetate and analyzed by HPLC on a C-8 reversed phase column at 282 nm. The recoveries of 6-, 8-, and 10-gingerol, and 6-shogaol from the ginger dietary supplements and ginger-containing products were 94.7+/-4.1, 93.6+/-3.4, 94.9+/-4.0, 97.1+/-3.8%, respectively. The within-day coefficients of variation for 6-gingerol, 6-shogaol, 8-gingerol, and 10-gingerol standards at 50.0 microg/mL were 2.54, 2.38, 2.55, and 2.31%, respectively. The lower limit of quantitation was 25 ng injected. The standard curves for 6-, 8-, and 10-gingerol and 6-shogaol were linear from 10.0 to 1000 microg/mL. The variation (CV's) in the 6-gingerol, 6-shogaol, 8-gingerol, and 10-gingerol concentrations of nine different ginger root dietary supplements were 115.2, 45.7, 72.3, and 141.7%, respectively. The gingerol composition of various ginger-containing spices, teas, and beverages also were found to vary widely. The proposed method can be used for the analysis and standardization of 6-, 8-, and 10-gingerol in ginger-containing dietary supplements, spices, food products and beverages and as a method for determining the amounts of 6-shogaol as a marker for 6-gingerol stability.