[Some criteria for the planning and evaluation of the ruggedness test of HPLC methods]

Ruggedness is a measure of the reproducibility of the individual test results when the procedure is used repeatedly to determine the same homogeneous sample in a variety of specified experimental conditions. Ruggedness testing can be divided into two major groups: Type-A, when the influence of the changed environmental conditions (different equipment, analysts, etc.) on the analytical performance parameters and results are tested, and Type-B, when the effect of variation in the experimental conditions are checked. In the latter case, Type-B group can be further classified into two major subgroups: ruggedness testing of sample preparation and chromatographic separation. Checking sample preparation for ruggedness testing includes the investigation of various sample preparation procedures, such as: liquid-liquid extraction, solid phase extraction, direct sample introduction and derivative formation. The investigation of column-to-column variability, changes in the instrumental and experimental conditions belongs to the ruggedness testing of chromatographic separation. In this paper the basic principles of selection for experimental variables for various ruggedness tests are discussed introducing a new possibility to design multivariable-multicriteria system, and the evaluation of a single-variable-single-criterion system, as well. In general, from the work introduced in this paper, it can be concluded that when new analytical methods are developed, it is quite important to be aware the sensitivity of the method to variations in the specified conditions. For adequate performance of ruggedness testing: a) the factors (variables) which have significant influence on the chromatographic results can be firstly selected, b) maximum acceptable deviations from the prespecified experimental conditions can be decided, and c) the acceptable deviations from the values of the prespecified analytical performance parameters can be defined.