Problem: Chromatographers have an ongoing need to increase productivity and decrease costs. This can be accomplished in part by leveraging higher efficiency HPLC columns to increase analysis speed. Significant improvements have been made in the preparation of sub-2 μm HPLC packing materials, which provide high-efficiency separations in less time when packed in shorter columns. Unfortunately, columns packed with sub-2 μm particles typically generate pressures that exceed the limits of standard HPLC instruments and require the use of ultra-high pressure HPLC systems, which can be cost-prohibitive.
Solution: Kinetex™ core-shell HPLC particle technologies provide a high-efficiency, low-pressure solution for laboratories looking to increase productivity and decrease costs without investing in a UHPLC system. Coreshell particles can be used with high mobile phase flow rates to further reduce analysis time without significant losses in separation efficiency, whereas the performance of fully porous particles begins to drop off sharply at high flow rates. The chromatograms shown in the figure demonstrate the potential of Kinetex HPLC columns to reduce analysis time, compared to traditional 5 μm fully porous particles, without compromising analyte resolution or generating extreme backpressures.
UHPLC systems have been engineered with sub-2 particle, high-pressure applications in mind, resulting in complex pump redesigns that add significantly to system cost. However, investigations have shown that straightforward adjustments can be made to existing HPLC systems to significantly increase performance with core-shell columns. These adjustments, which include increasing detector scan rates and reducing system dwell volume require little to no additional investment. The column charts (right) show the effect of HPLC system optimization on the separation efficiency observed with Kinetex compared to 5 μm fully porous particle columns and how those values compare to 1.7 μm fully porous columns used with UHPLC systems.
The high separation efficiency of core-shell particles is due in large part to faster analyte mass transfer from the mobile phase into and out of the stationary phase because only the outer porous layer of the particle allows diffusion. A 2.6 μm Kinetex core-shell particle has a non-porous core approximately 1.9 μm in diameter and an outer porous layer of 0.35 μm. These core-shell particles also have exceptionally consistent shape and size, which helps to improve separation efficiency by reducing the variability in analyte movement between particles. The improved dynamics of analyte movement through these columns results in higher effective peak capacities and separation efficiencies comparable to those of fully porous 1.7 μm particles. However, because the core-shell particle diameter is 2.6 μm, the backpressures generated are more comparable to those of columns packed with 3 μm fully porous particles. Kinetex columns are also available with 1.7 μm particles, which provide even higher efficiencies than the 2.6 μm but also result in higher backpressures.
Core-shell technology can increase productivity in the laboratory today, allowing for an upgrade in the performance of conventional HPLC instrumentation to compete on a new level of speed and performance.
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