Practical Applications of DryLab in the Laboratory

In this example, the separation goal was the resolution of a single sulfa ted impurity from a complex mixture for quantification by UV detection. Ideally, an isocratic separation would be desired for simplicity. Previous trial-and-error method development had failed to yield a suitable separation, but did suggest the initial use of a Cjg column with a mobile phase based on pH 3,20 mM phosphate buffer plus acetonitrile (MeCN). The results of prior experiments also pointed to the use of a narrower gradient range (25-60% MeCN) for the initial software calibration experiments. 

two DryLab calibration runs were carried out, as shown in Fig. 2 a spiked sample was used with gradient times of 15 and 90 min. Peak tracking by area matching and photodiode array showed that the separation of the peak of interest was not achieved in either run (Fig. 3). Also, significant changes in peak elution order were observed. Retention data from the two runs were modeled by DryLab to yield the resolution map of Fig. 4, for isocratic separation of the sample as a function of %B (i.e., % MeCN). In Fig. 4, only the resolution of peak 3 is 

Initial gradient chromatograms for the development of a quantitative assay for impurities. Sample spiked with compound of interest (see arrows). 

Detailed view of separations (A) and (B) shown in Fig. 2. Peak 3 is the peak of interest. 

Resolution map for the separation of peak 3 from other peaks as a function of% acetonitrile (B) in the isocratic mobile phase. 

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