Going to ISCC & GCxGC in Fort Worth this year? Don’t miss these presentations by Restek’s expert chromatographers. Stop by our booth or attend a presentation—we’re excited to share our research and discuss solutions to your toughest chromatography challenges!
GC-MS Analysis of Phthalates: Comparison of GC Stationary Phase Performance
Dan Li, Rebecca Stevens, Chris English, Anzi Wang
Phthalates are ubiquitous in the environment and have attracted attention due to their potential adverse impact on human health. For this reason, detection and separation of phthalates has become a necessity. Gas chromatography is an effective approach for separating phthalates, and it can be paired with several detection techniques, including electron capture (ECD), flame ionization (FID), and mass spectrometry (MS). In this study, Pro EZGC gas chromatographic modeling software was employed to determine the optimal stationary phases and conditions for phthalate GC-MS analysis. The separation of phthalates was compared on seven different stationary phases: Rtx-440, Rxi-XLB, Rxi-5ms, Rtx-50, Rxi-35Sil MS, Rtx-CLPesticides, and Rtx-CLPesticides2 phases. In all cases, 18 EPA- and EU-listed phthalates were analyzed in less than 6 minutes. In addition, an extended list of 37 phthalates was analyzed in less than 40 minutes using an optimized method. Both Rtx-440, which is unique to Restek, and Rxi-XLB columns showed the best resolution of the complex phthalate mixture.
Evaluating Mass Overload on Superficially Porous Particles
Edward G. Franklin, C. Vernon Bartlett, Justin Steimling, Ty Kahler
Superficially porous particles (SPP) are a powerful analytical tool for achieving fast LC analyses. The solid, impermeable core present in these particles increases the column efficiency by decreasing the diffusion path. However, the solid core also significantly reduces the surface area that is typically available in traditional fully porous materials (FPP). There is a potential concern that arises from a reduction in surface area: column loading ability. Column overloading (mass overload) occurs when the amount of material injected onto the column exceeds the available active sites of the stationary phase. The purpose of this study was to evaluate a series of analytes and determine the effects the solid core has on the loading ability of superficially porous particles.
Affecting Selectivity and HILIC Retention on a FluoroPhenyl Stationary Phase
Vernon Bartlett, Edward G. Franklin, Frances Carroll, Shun-Hsin Liang, Sharon Lupo, Ty Kahler
In this study, we have set out to explore the retention mechanisms of the FluoroPhenyl stationary phase. The FluoroPhenyl phase may be described as having mixed-mode and/or HILIC retention and selectivity. HILIC and mixed-mode capabilities offer retention mechanisms that vary, or are orthogonal to, typical reversed-phase columns like C18s. These chemical interactions are generally not well understood or easily demonstrated, which may be frustrating and leave chromatographers not using the phase to the fullest potential.
The FluoroPhenyl phase offers unique selectivity by incorporating strongly electronegative fluorine atoms on a phenyl ring. In addition to traditional reversed-phase dispersive interactions, this phase exhibits polar, cation-exchange, and HILIC retention mechanisms. Our focus in this presentation is on method changes, including temperature, mobile phase composition, acid strength and concentration, and how these changes affect the selectivity of targeted analytes. By demonstrating the influence of method changes on this phase, we aim to gather a better understanding of the interactions provided by the FluoroPhenyl phase and its use as a HILIC or mixed-mode phase.
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