Method Development with ChromSword

1 Off-Line Mode (Computer-Assisted Method Development) 

ChromSword works with different retention models. The retention model is a type of experiment-based mathematical expression that describes the relationship between the retention of a compound and its properties, as well as the conditions appertaining to the chromatographic experiments. The determination of retention models that adequately describe the effect of chromatographic conditions on the retention of compounds in a sample is very much the focal point in method development software. In this case, on the basis of only a few experiments, the 

ChromSword supports three approaches for the determinahon of retenhon models in reversed-phase HPLC  

k is the retention factor value of a compound, C is the concentrahon of an organic solvent in the mobile phase, and a, b, d, e, are parameters of equations that must be determined by the software for each compound from the retention data obtained with different concentrations of the organic solvent in the mobile phase. The first linear model is the simplest. It requires two initial experiments to start optimizing, but sometimes it does not predict completely correctly the effect of the concentration of an organic solvent in a mobile phase. Additional experiments do not as a rule lead to improvement in the accuracy of the linear model. The quadratic model describes retention more adequately. Additional experiments improve the accuracy, and three initial experiments are required to start computer optimization. The higher the power of a model, the more complex retention behavior can be described and the more initial experiments must be performed to start optimization of the separation. 

ChromSword supports the optimization of separation for polynomial models up to a power of six. Thus, the most complex retention-concentration effects can be described and the separation optimized. AU polynomial models predict the retention of solutes rather precisely in the interpolation region of those concentrations studied. These models are less reliable in the extrapolation region. For example, if experiments were performed with 40% and 50% of organic solvent in a mobile phase, one can expect rather good prediction of retention and separation in the region between these concentrahons and less accuracy in the regions of 30-35% and 50-55%. Extrapolahon to wider hmits very often leads to substantial deviations between predicted and experimental data. 

---

ChromSword for computer-assisted HPLC method development was developed between 1990 and 1995 as an extension of ChromDream HPLC method development software [1]. In 1999, the first version for automatic HPLC optimization was developed and launched by S. Galushko in collaboration with Merck KGaA (Darmstadt, Germany). As a result of cooperation with VWR International Scientific Instruments, Darmstadt, Germany, Hitachi High Technologies... 

The software has been equipped with a fimction such that it is not only able to conduct experiments with one column/organic modifier/buffer combination, but to automatically optimize a method by trying different column/organic modifier/ buffer combinations. The system provides imattended HPLC method development and performs autonomous development and optimization of isocratic and gradient methods for selection of the best variant column, pH value, solvent Two typical hardware configurations and other mixed combinations are supported by ChromSword standard and powerful. 

ChromSword is a software tool that is able to find the optimum conditions for H P LC automatically. Most optimizations may be achieved overnight or in weekend nms, resulting in a substantial reduction in working time and effort compared to that normally involved in method development Since the system offers several different isocratic and gradient optimum solutions, the user can select the solution which fits best for his or her particular application. The system optimizes for optimum peak resolution in minimum analysis time. Minimization of the nm time of routine methods offers the potential to substantially increase throughput and productivity in the analytical laboratory. The program also makes complex HPLC method development accessible to those with little HPLC experience. 

If one plans to purchase an automatic method development system, one will first have to get an idea of the systems that are presently available on the market Essentially, only ChromSword Auto and, since recently, AMDS (based upon DryLab) are available, along with H EUREKA, which is presently being established on the market Characteristics and experiences with the three systems are compared in Table 2. This table can also be used as a check list in order to facilitate the decision in favor of one system or the other. 

There are several software and automated systems for HPLC method development and optimization, such as Drylab , Chromsword , and ACD/AutoChrom MDS, and others (43 7). Their principles can be applied to UHPLC. In addition. Waters Corp. (Milford, MA) has recently promoted Fusion Method Development software. Fusion Method Development software from S-Matrix integrates seamlessly with Water s ACQUITY UPLC and Empower 2 Chromatography software to automate method development. The software automatically generates instrument methods and sample sets. Another feature of this software is to visualize data by statistically fitting the results. However, it cannot generate simulated chromatograms at predicted conditions, like Drylab can. 

---