Resolution of hyphenated two-way chromatographic data using the slice-scan method

In this paper, the slice-scan (SS) method was presented for the resolution of hyphenated chromatographic data, which scans the two-way data at each chromatographic retention time point, and hence obtains the corresponding spectral “slice”s. Then, by means of a novel data transformation method called convolution transformation, a certain spectral slice can be transformed to hundreds of convolution spectra, revealing the specific information hidden in the original spectral slice, which provides appropriate conditions for analyzing the overlapping chromatographic peaks. Using the SS method, the accurate starting and ending points of the selective regions in the overlapping peaks can be identified by calculation of differential points ratio followed by the definition of reference region. Different from the existing methods depending on peak resolution, this method does not resolve the overlapping clusters into pure chromatograms and spectra before the interested component is determined; it searches for the zero-crossing points of the interfering component within its convolution spectra instead, at which the interested component can be determined directly from the two-component spectral slices of the determined chromatographic profile. The efficiency of the SS method was demonstrated on a three-component mixture of quinolone medicines (Enoxacin, Norfloxacin and Ciprofloxacin), characterized by an overlapping profile of hyphenated chromatographic data, and encouraging results have been obtained.