System Suitability Requirements for Liquid Chromatography Methods: Controlled Parameters and their Recommended Values (Review)

Abstract

Chromatographic analytical results can be affected by various factors associated with the chromatographic system. Requirements for system suitability testing (SST) are introduced to minimize the risk of such factors having a critical influence on the results. This review covers the chromatographic parameters for SST and their recommended values and categorizes them into five groups depending on the purpose for their introduction into the SS requirements. The type of method (isocratic or gradient) and purpose of the testing (determination of the main substance or impurity content, peak asymmetry, etc.) are considered. Some additional intralaboratory parameters for SST in serial analyses (routine testing) are studied. Arecommendation to introduce the condition N ≥ 0.9Nexp, where Nexp is the smallest experimental number of theoretical plates N at which the requirements for system sensitivity (S/N, signal/noise) is still fulfilled for testing before and during the method validation, is given for the first time for gradient methods of impurity determination. This condition is justified from a theoretical viewpoint. Attention is drawn to the expediency of robustness testing to refine the SST requirements. Information given in this review supplements significantly recommendations of the European Pharmacopoeia, US Pharmacopeia, and the State Pharmacopoeia of the Russian Federation for chromatographic SST. These recommendations are important for improving the reliability of chromatographic system suitability control.