Robustness testing of liquid chromatographic method for determination of itraconazole and its impurities applying fractional factorial design

Abstract

Test of robustness is a part of the method validation and it is carried out in the end of the method development or in the beginning of the method validation. The purpose of robustness testing is to avoid problems in interlaboratory studies and to define parameters with the greatest impact on the method. The chosen factors are investigated within the range that slightly exceeds the expected variations when the method is transferred from one instrument/laboratory to another. The application of experimental design is recommended to perform robustness testing and two most often utilized - Plackett-Burman and fractional factorial design - are described. Furthermore, the manners of evaluation of factor significance, the methods for calculation of the range of insignificance for significant factors and the procedure for determination of system suitability test parameters are described. Such an approach of robustness testing was applied to the high performance liquid chromatographic method for determination of itraconazole and its impurities B and F. The robustness is tested by using fractional factorial design and 4 factors in 11 experiments were analyzed. After the application and the analysis of all the suggested steps for robustness, the impact of factors on the system responses was evaluated, insignificance ranges were defined and system suitability test limits for suggested method were determined.

Test robusnosti metode predstavlja deo validacije metode, a izvodi se na kraju razvoja metode ili na početku validacije. Testiranje robusnosti je uvedeno da bi se izbegli problemi u međulaboratorijskim ispitivanjima i da bi se definisali faktori koji imaju najveći uticaj na metodu. Izabrani faktori ispituju se u intervalu koji blago prevazilazi varijacije koje se očekuju kada se metoda prenosi sa jednog instrumenta/laboratorije na drugi. Za testiranje robusnosti korisno je primeniti eksperimentalni dizajn. U ovom radu opisana su dva najčešće korišćena, Plakett-Burman-ov i frakcioni faktorski dizajn. Takođe, opisani su i načini procene značajnosti faktora, zatim načini izračunavanja intervala neznačajnosti za značajne faktore, kao i postupak određivanja parametara za procenu pogodnosti sistema. Ovakav pristup procene robusnosti metode primenjen je na metodu tečne hromatografije za određivanje itrakonazola i njegovih nečistoća B i F. Robusnost je testirana primenom frakcionog faktorskog dizajna, a analizirana su četiri faktora kroz 11 eksperimenata. Sprovodeći i analizirajući sve predložene korake za robusnost procenjen je uticaj faktora na faktore rezolucije kao odgovore sistema, definisani su intervali neznačajnosti i određeni limiti za proveru pogodnosti sistema predložene metode.