Robustness tests on the United States Pharmacopoeia XXVI HPLC assay for ginsenosides in Asian and American ginseng using an experimental design

Ruggedness and robustness testing is applied prior to the transfer of a method to various laboratories. It is especially important for official methods that are widely and formally used. Ginsenosides (Rg1, Re, Rf, Rb1, Rg2, Rc and Rd) occurring in Asian and American ginseng, were assayed using high-performance liquid chromatography (HPLC) methods issued by the United States Pharmacopoeia (USP XXVI and XXVII). They have a delicate system suitability to properly execute the method. A robustness test was carried out using an experimental design approach, in order to indicate the suitability of the method in a broad execution range. Seven factors are selected and examined by a fractional factorial design. Twelve responses, involving quantitation-related items, such as recovery of Rg1 and Rb1, and qualitative items, such as resolution (Rs), theoretical plate number (N), relative retention time (RRT) of two critical pairs, are measured. The calculated effects are both graphically and statistically interpreted to identify the significant factors. The robustness tests using fractional factorial design on the assay of ginsenosides provided an effective approach as part of a validation of the method on phytomedicines. It also indicated that methods with different selectivity, of which some are possibly unsuitable, could pass the existing system suitability limits.