The box-counting or capacity dimension algorithm, known from the fractal mathematics literature, is used to measure the dimensionality D of chromatographic separation techniques for any number of dimensions. It is shown that D has limit properties that match Giddings' sample dimensionality s. D values are shown to be sensitive to the uniformity of peak spacing. A number of examples are given where D is calculated for various limits in one- and two-dimensional separations and for heart-cutting separations. The use of D as a quantitative measure of multidimensional orthogonality is suggested as D, due to the scale-free nature, is not dependent on the effective separation area. The connection to statistical peak overlap theory is discussed.
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http://dx.doi.org/10.1016/j.chroma.2010.11.016 | DOI Listing |
J Chromatogr A
December 2024
School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China. Electronic address:
The evolution of precursors to form secondary organic aerosol (SOA) is still a challenge in atmospheric chemistry. Chamber experiments were conducted to simulate the ambient OH oxidation of naphthalene and α-pinene, which are typical markers of anthropogenic and biogenic emissions. Particulate matters were sampled by quartz filters and were analyzed by comprehensive two-dimensional gas chromatography (GC×GC) coupled with a thermal desorption system (TD) and a mass spectrometer (MS).
View Article and Find Full Text PDFJ Chromatogr A
December 2024
Department of Chemical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK. Electronic address:
To elevate the separation performance, two-dimensional liquid chromatography (2D-LC) uses two chromatographic columns with different stationary phases to diversify solute interactions with the resin, hence providing a second "dimension" to solute-specific separation. Developing methods for 2D-LC starts therefore with preliminary column selection. Selecting columns that yield (metaphorically) orthogonal dimensions is of utmost importance, but remains challenging.
View Article and Find Full Text PDFJ Chromatogr A
January 2025
Ionis Pharmaceuticals, Carlsbad, CA 92010, USA.
The increased effectiveness of small interfering RNAs (siRNAs) to induce gene silencing has brought a great therapeutic promise to many diseases. siRNAs are under highly active current research and development. Ligand conjugation and chemical modifications of the sense (SS) and antisense (AS) strands of the siRNA duplex improve stability and facilitate delivery, but significantly increase the complexity of the analytical requirements.
View Article and Find Full Text PDFAnal Chem
December 2024
Department of Analytical Chemistry, University of Pardubice, Faculty of Chemical Technology, Studentská 573, Pardubice 53210, Czech Republic.
Multidimensional chromatography offers enhanced chromatographic resolution and peak capacity, which are crucial for analyzing complex samples. This study presents a novel comprehensive online multidimensional chromatography method for the lipidomic analysis of biological samples, combining lipid class and lipid species separation approaches. The method combines optimized reversed-phase ultrahigh-performance liquid chromatography (RP-UHPLC) in the first dimension, utilizing a 150 mm long C18 column, with ultrahigh-performance supercritical fluid chromatography (UHPSFC) in the second dimension, using a 10 mm long silica column, both with sub-2 μm particles.
View Article and Find Full Text PDFJ Chromatogr A
January 2025
Beijing Institute of Radiation Medicine, Beijing, 100850, China; Graduate School, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China. Electronic address:
Dai-Bai-Jie, the root of the plant Marsdenia tenacissima from the Asclepiadaceae family, is well-known for its therapeutic effects in clearing heat, detoxifying, reducing swelling, and relieving pain as one of the most commonly used Dai medicine. Due to numerous structurally similar C21 steroidal compounds in Dai-Bai-Jie, chemical composition profiling has been substantially challenged. In this study, an offline two-dimensional chromatographic method (LC × SFC separation system) was developed to address these issues.
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