Abstract: The state-of-the-art instruments for the determination of viscosity of liquids typically require a significant amount of sample, and have relatively low throughput due to manual and sequential measurements. In this study, it was demonstrated that the pressure generated by the flow of viscous fluids through a capillary could be precisely measured employing high-pressure liquid chromatography systems (HPLC) using glycerol solutions of moderate viscosity as a mobile phase, and correlated to the dynamic (absolute) viscosity. The parameters allowing calculation of the viscosity of glycerol calibration standards as a function of temperature were established. The measurements were made with volumes as small as 10 μL, and the use of an autosampler permitted unattended analysis of a large number samples. The method appears to be particularly well suited for the development of viscous formulations of therapeutic, protein-based macromolecules, where the amount sample is typically limited and relatively wide ranges of conditions are considered in the optimization process. The utility of the methods was illustrated by application to the development of concentrated inactivated virus vaccines.
Abstract: It is my great pleasure to serve as the first editor-in-chief for Chromatography, and welcome you all to the readership. This journal will enable us to communicate our findings in “open access” while maintaining the very high scientific requirements of the few other journals that are focused on the type of science that we all find so very interesting. It is safe to say that chromatographic separations are the single most heavily used techniques in the larger field of analytical chemistry, whether applied or fundamental. Without chromatography, we would struggle to answer many of the pressing scientific questions of our time, and without improvements and advancements we will still struggle to probe more deeply into the challenges of the future. Whether it is for better understanding and characterization of starting materials and products, qualitative determination of unknowns in important matrices, quantification of the materials that impact our lives, or the discovery of the emerging compounds of the future, chromatography is the science that ties our various research fields together.
Abstract: The vast cache of methods used in polymeric monolithic column modification is presented herein, with specific attention to post-polymerization modification reactions. The modification of polymeric monolithic columns is defined and can include the modification of pre-existing surface groups, the addition of polymeric chains or indeed the addition of structures such as nano-particles and nano-structures. The use of these modifications can result in the specific patterning of monoliths, useful in microfluidic device design or in the investigation of modification optimization.
Abstract: In this study, the separation parameters in micellar electrokinetic chromatography (MEKC)-laser-induced fluorescence (LIF) were optimized for the separation of red and yellow historical dyes in 20 mM borate buffer with 20 mM sodium dodecyl sulfate (SDS). Separation conditions were optimized by changing pH, organic modifier (methanol and acetonitrile) concentrations and applied voltage. The mixtures of dyes used in this study included four anthraquinone dyes (alizarin, purpurin, emodin and carmine) and six flavonoid dyes (luteolin, apigenin, kaempferol, quercetin, morin and myricetin). For this work, dyes were introduced electro-kinetically (10 kV for 5 s) into a 50 cm capillary (10 µm id) and separated using a running potential of 18, 20, 22 and 25 kV. Absolute limits of detection for most of these dyes was less than 1 pg. For dyes such as alizarin, improved detection limits were achieved at pH = 9.24; however dyes such as purpurin had significantly improved detection limits at pH = 8.0. The successful extraction and identification of a number of dyes in plants and textiles samples is also described.
Abstract: Flavonoids are bioactive constituents in Oroxylum indicum seeds, an Asian traditional remedy used for the treatment of respiratory infections. In this study the first capillary electrophoretic method for their determination is presented. By using a 25 mM borax buffer at pH 9.2 containing 10 mM SDS as detergent, the determination of seven flavonoids was feasible in only 13 min. Method validation confirmed that the assay is in accordance with ICH requirements in respect to linearity, selectivity, sensitivity, accuracy and precision. Quantitative results revealed that baicalein-7-O-gentiobioside is the most abundant flavonoid in the drug (1.19 to 5.33%), followed by other baicalein derivatives (7-O-glucoside, 7-O-glucuronide). These observations were in good qualitative and quantitative agreement with LC-MS results.