In the present study a computer simulation software DryLab and a chemometric (response surface) approach were used in developing and optimizing a reverse-phase HPLC separation of moxifloxacin and its related impurities and degradation products of moxifloxacin. The separation of four synthesis-related impurities was achieved on a Waters C18 XTerra column using a mobile phase of (water + triethylamine (2%, v/v)): acetonitrile = 90:10 (v/v%), the pH of water phase being adjusted with phosphoric acid to 6.0. The column was thermostated at 45 °C. The resolution between the two least resolved impurity peaks was in average, R_s,min > 1.5. Method validation parameters indicate linear dynamic range 0.2–2.0 μg/ml with LOQ ca. 0.20 μg/ml and LOD ca. 0.05 μg/ml for all analytes. The method was applied for the impurities determination in drug tablets and infusion (Avelox®, Bayer AG) and for degradation products determination in a stability study of moxifloxacin. The impurity content in the tablets and infusion was quantified as 0.1% of total drug. 

A comprehensive automated strategy for the development of a RPLC-UV-method for a basic drug candidate (pKa 7.7), its impurities, and degradants was demonstrated by using multidimensional screening and analysis (MeDuSA) and DryLab computer optimization software. DryLab software was used to model the effect of temperature, pH, and ionic strength of the buffer on resolution and peak shape to determine the design space of the method and establish the optimal operating conditions. In silico optimization supported by DryLab enabled the determination of the optimum conditions without carrying out trial-and-error simulations. Excellent agreement between DryLab simulation and experimental results was obtained. As a result, decreased run time (from 35 to 14 min compared to the original method) was developed.

The paper describes a strategy for the systematic development of ultra high pressure liquid chromatographic (UHPLC or UPLC) methods using 5 cm × 2.1mm columns packed with sub-2µm particles and computer simulation with the DryLab® package. Data for the accuracy of computer modeling in the Design Space under UPLC conditions are reported. An acceptable accuracy for these predictions of the computer models is presented. The work illustrates a method development strategy, focusing on time reduction up to a factor 3–5, compared to the conventional HPLC method development and exhibits parts of the Design Space elaboration as requested by the FDA and ICH Q8R1. Furthermore this paper demonstrates the accuracy of retention time prediction at elevated pressure (enhanced flow-rate) and shows that the computer-assisted simulation can be applied with sufficient precision for UHPLC applications (p > 400 bar). Examples of fast and effective method development in pharmaceutical analysis, both for gradient and isocratic separations are presented.

The main objective in all optimization procedures is to define the most appropriate conditions for rapid, sensitive, precise, and reproducible analysis, as economically as possible. Experimental design and DryLab optimization software have been used to optimize a liquid chromatographic method for separation of lercanidipine and its three impurities. In both methods of optimization the acetonitrile content and pH of the mobile phase were factors extracted for analysis, resolution of a critical pair was output in both cases. Data obtained from both optimization methods were compared and appropriate conclusions were extracted with the objective of gaining a complete view of chromatographic behavior. Detailed description was obtained by use of a three-dimensional graph and DryLab maps.

A stepwise method development strategy was employed in developing a robust HPLC method to resolve several closely eluting process impurities associated with a novel diabetes compound. The strategy consisted of rapid column screening, optimization of mobile phase compositions and separation temperature, DryLab modelling, and experimental verification of optimized separation conditions. The column evaluation process involved screening of a series of 20 columns varying in bonding chemistry using four sets of mobile phases composed of water, ACN and/or MeOH at three different pH’s. The screening process resulted in identifying two promising columns: XBridge Shield RP18 and SunFire C18. The effects of organic modifiers and separation temperatures were then evaluated to narrow down the chromatographic separation parameters. DryLab® was used to predict optimized gradient profile and separation temperature. Finally, the DryLab® predictions were verified experimentally. The study demonstrates that factors such as stationary phase composition, organic modifiers, pH and separation temperature have profound and often complex effects on chromatographic conditions. Therefore, it is critical to adopt a rational strategy as demonstrated here to evaluate the interplay of these factors, there by greatly enhancing method development efficiency.

The development of gradient methods in HPLC is a difficult task. The transfer of the methods requires deep understanding the process in the column and the factors, which are required for a safe operation in the routine lab. The talk will discuss the aspects, how to make reliable methods using computerized design in the development.