MPa Backpressure Research Articles

Evaluation of RPLC stationary phases for tocopherol and tocotrienol positional isomer separation: Method development and profiling

Reversed-phase separation of tocopherols (Ts) and tocotrienols (Ts) using C18 stationary phases results in the coelution of β and γ positional isomers, leading to identification errors. This study investigates the potential of alternative stationary phase chemistries to effectively resolve tocochromanols, specifically focusing on the critical pair of β and γ positional isomers. Initial screening of seven different stationary phases (C18, C18-PFP, C30, PFP, 5PYE, πNAP, and RP-Amide) was conducted. Linear solvent strength (LSS) studies were performed to assess the impact of the organic modifier (methanol) and temperature on the chromatographic performance parameters. Five columns were found to be suitable for the tocochromanol separation and two different chromatographical conditions per column were proposed. Elution order of tocochromanols was unique for 5PYE, πNAP and C30 columns in comparison to RP-Amide and PFP. Method development for the quantitative analysis of four tocopherol and four tocotrienol homologues was performed. The optimised method employed the RP-Amide (150 × 4.6 mm, 2.6 μm dp) superficially porous particle column, mobile phase of methanol:water of 92:8, v/v, with a flow rate of 1.0 mL/min, column oven temperature of 40 °C and fluorescence detection (λex 295 nm, λem 330 nm). The analysis run time was 10.5 min with 13.6 MPa back pressure. The method was validated and the obtained LOQs were found to be 1.30-3.13 μg/mL. The method developed was successfully applied for the determination of tocochromanols in twenty samples with unique tocochromanol profiles. Principal component analysis illustrated three distinct groups based on the tocochromanol profile.

Study of Backpressure on the Composition and Characteristics of the AA5083 Alloy During ECAPed

Equal Channel Angular Processing Process at room temperature along varying backpressure level and numbers of passes produced hefty billets of 25 mm×25 mm×100 mm industrial alloy AA5083 with an ultrafinegrained microstructure. Supersaturated solid iron in an aluminium matrix was treated in brittle cast AA5083 during Equal Channel Angular Processing with Sixteen passes and a 285 MPa backpressure. The Equal Channel Angular Processing alloy’s strength, ductility, and microhardness were all greatly improved. Increased backpressure improves ductility of Equal Channel Angular Processing alloys, the workability and delays the craking of intermetallic particles. Alloys treated by Equal Channel Angular Processing have improved workability due to backpressure. The AA5083 alloy’s strength and microhardness were greatly improved. When an initially coarse-grained alloy undergoes 3 passes of Equal Channel Angular Processing with a 220 MPa backpressure, its microhardness and room strength (185 HV, UTS = 327 MPa) are significantly higher than their typical values following conventional processing with cold rolling or hot pressing. In Equal Channel Angular Processing, a super saturated solution was generated with a peak soluble of 0.6 wt.% of iron allow the ageing of the usually non-hardenable metal. The cast alloy treated using the Multi-pass approach has positively impacted toughness, elasticity, and microhardness.

Research on Managed-Pressure Running Casing in Oil and Gas Wells with the Negative Pressure Window

The failure of managed-pressure running casing in oil and gas wells may lead to complex accidents such as overflow or leakage. The technique of using multi-density gradient drilling fluids in wellbores with negative pressure windows (NPWs) is often used to deal with this situation. Therefore, it is vital to analyze the dynamic slurry column structure and calculate the wellbore pressure during casing running. For this issue, the model of transient surge pressure is established during casing running. The calculation equation of the model is proposed, and the calculations of the wellbore pressure are carried out with the exploration of Well LT-X1, located in the Xinjiang oil field. A circulation scheme is designed as follows: Circulate 125 m3 of drilling fluid with a density of 2.45 g/cm3 and 155 m3 of drilling fluid with a density of 2.35 g/cm3 at a depth of 3560 m. From there, circulate 164 m3 of drilling fluid with a density of 2.35 g/cm3 at a depth of 5900 m. Finally, at a depth of 7050 m, circulate 250 m3 of drilling fluid with a density of 2.30 g/cm3. The casing running speeds and back-pressure values were designed as follows for the respective well sections: 0–1523 m: 0.160 m/s casing speed, 0 MPa back pressure; 1523–3560 m: 0.160 m/s casing speed, 1.641 MPa back pressure; 3560–5900 m: 0.145 m/s casing speed, 2.427 MPa back pressure; 5900–6674 m: 0.137 m/s casing speed, 4.041 MPa back pressure; 6674–7050 m: 0.124 m/s casing speed, 4.457 MPa back pressure. The results show that optimizing structure of the multi-density gradient drilling fluid with different densities and applying annular back pressure in stages, with the accurate calculation of wellbore pressure, can achieve the goals of leak-proofing and pressure-stabilization. It is concluded that this result may serve as the foundation for managed-pressure running casing technology.

Effect of water-soluble organic acids on wettability of sandstone formations using streaming zeta potential and NMR techniques: Implications for CO2 geo-sequestration

Rock wettability is influenced by several conditions, and one such factor is the potential at the rock/fluid interface. While most studies have reported zeta potential in this context, very few investigations have carried out streaming potential measurements. Further to this, most previous studies have only evaluated zeta potential/streaming potential for NaCl brine-clean sandstone systems, while it is clear that organic matter exists in subsurface rock. However, the effect of these forms of organic matter on streaming potential has not yet been probed. Accordingly, in this study streaming potential measurements were firstly conducted on pristine San Sabasandstonesamples with 0.3 mol.dm3 NaCl brine-saturated at (6.895 MPa overburden and 3.447 MPa back-pressure). Secondly, the streaming potential of the aged samples was measured under identical conditions (the cores were saturated with aqueous HA solutions of different concentration; 1–100 mg/L) in 0.3 mol.dm−3 NaCl. Thirdly, a comparative analysis of zeta potentials was conducted via electrophoretic and streaming potential. Lastly, the T2 spectrum for the initial water saturation of pristine and aged cores, along with the T2 spectrum of residual water saturation after CO2 flooding for pristine and aged cores, were measured with NMR core flooding measurements. Accordingly, this work analyses the effects of organic acids on wettability alteration in sandstone formation in accordance with these procedures. A strong correlation exists between surface adsorption of organic acid and streaming potential coefficient, where the amount of residual water saturation decreases in humic-acid aged cores – suggesting the presence of organic acid that changes wettability towards CO2 wet in pores, where the CO2 displaces more brine in aged cores compared to pristine cores.

Polybenzimidazole Ultrathin Anion Exchange Membrane with Comb-Shape Amphiphilic Microphase Networks for a High-Performance Fuel Cell.

A comb-shape amphiphilic cationic side chain is proposed to well-balance the water sorption in anion exchange membranes (AEMs), in which the cationic group is in between of an ether-containing hydrophilic spacer and an alkyl hydrophobic spacer. By fully grafting the amphiphilic side chains onto polybenzimidazole (PBI), comb-shape amphiphilic microphase networks are well-developed in the AEMs, in which the alkyl hydrophobic network greatly restricts water swelling and the ether-containing hydrophilic network keeps the hydration of the cationic groups and enlarges the ion conductive channel. The as-prepared membranes achieve a high conductivity of about 91.2 mS cm-1, an extremely low swelling ratio of about 8.1% at 80 °C, and good mechanical properties at a hydrated state (tensile strength and elongation at a break of about 14.6 MPa and 77.5%, respectively). Benefits from the balanced water sorption in AEMs, the H2/O2 fuel cell with a 10 μm ultrathin membrane could withstand 80 °C and 0.1 MPa back pressure and achieve a high open circuit voltage of about 1.0 V and a high peak power density of about 631.5 mW cm-2. This work provides a new insight into the design of high-performance AEM.

3D-Zipped Interface: In Situ Covalent-Locking for High Performance of Anion Exchange Membrane Fuel Cells.

Polymer electrolyte membrane fuel cells can generate high power using a potentially green fuel (H2) and zero emissions of greenhouse gas (CO2). However, significant mass transport resistances in the interface region of the membrane electrode assemblies (MEAs), between the membrane and the catalyst layers remains a barrier to achieving MEAs with high power densities and long‐term stabilities. Here, a 3D‐interfacial zipping concept is presented to overcome this challenge. Vinylbenzyl‐terminated bi‐cationic quaternary‐ammonium‐based polyelectrolyte is employed as both the anionomer in the anion‐exchange membrane (AEM) and catalyst layers. A quaternary‐ammonium‐containing covalently locked interface is formed by thermally induced inter‐crosslinking of the terminal vinyl groups. Ex situ evaluation of interfacial bonding strength and in situ durability tests demonstrate that this 3D‐zipped interface strategy prevents interfacial delamination without any sacrifice of fuel cell performance. A H2/O2 AEMFC test demonstration shows promisingly high power densities (1.5 W cm−2 at 70 °C with 100% RH and 0.2 MPa backpressure gas feeds), which can retain performances for at least 120 h at a usefully high current density of 0.6 A cm−2.

Influence of mineralogy and surfactant concentration on zeta potential in intact sandstone at high pressure

Hypothesis:Zeta-potential in the presence of brine has been studied for its application within hydrocarbon reservoirs. These studies have shown that sandstone’s zeta-potential remains negatively charged, non-zero, and levels-off at salinities > 0.4 mol.dm−3, thus becoming independent of salinity when ionic strength is increased further. However, research conducted to date has not yet considered clay-rich (i.e. clay ≥ 5 wt%) sandstones. Experiments:Firstly, streaming potential measurements were conducted on Bandera Gray sandstones (clay-rich and clay-poor) with 0.6 and 2 mol.dm−3 NaCl brine-saturated in pressurised environments (6.895 MPa overburden and 3.447 MPa back-pressure). Secondly, the streaming potential was determined at identical conditions for the effect of two surfactants, SDBS and CTAB, at concentrations of 0.01 and 0.1 wt% on the clay-poor sample in 0.6 mol.dm−3 NaCl. Thirdly, a comparison of zeta potentials determined via electrophoretic and streaming potential was conducted. Accordingly, this work analyses the effects of mineralogy and surfactants within this process. Findings:Clay-rich sandstone possessed lower zeta-potentials than clay-poor sandstone at the two tested salinities. SDBS reduced zeta-potential and yielded higher repulsive forces rendering the rock more hydrophilic. Additionally, electrophoretic zeta-potentials were higher when compared to streaming zeta-potentials. Mechanisms for the observed phenomena are also provided.

High-Performance Ru 2 P Anodic Catalyst for Alkaline Polymer Electrolyte Fuel Cells

High-Performance Ru ₂ P Anodic Catalyst for Alkaline Polymer Electrolyte Fuel Cells

Computational study on the influence of nozzle eccentricity in spray formation by means of Eulerian Σ - Y coupled simulations in diesel injection nozzles

The present work analyses the effect of the eccentricity of diesel nozzle orifices over the spray behaviour by means of CFD simulations. Several orifice geometries with varying horizontal eccentricity (from 0.50 to 0.94) are selected. Their performance is assessed at a high injection pressure of 200 MPa, a 3 MPa back-pressure and non-evaporative conditions. The nozzle flow characteristics, including cavitation modelled by a Homogeneous Relaxation Model (HRM), are accounted for in the spray performance by means of a Σ - Y model. The code is validated via two reference nozzles, the so called ”Spray A” of the Engine Combustion Network plus a second nozzle from a production injector, and then extended to the eccentric geometries. The results and discussions include spray angle and penetration, air entrainment and flow parameters of the nozzle inner conditions versus the eccentricity value.

Surfactant-assisted incorporation of ZrO2 nanoparticles in quaternized poly(2,6-dimethyl-1,4-phenylene oxide) for superior properties of anion exchange membranes

Uniformly introducing inorganic additives into polymer matrix could effectively improve the properties of the polymer membranes. Herein, the ZrO2 nanoparticles containing a surfactant cetyltrimethylammonium bromide (CTAB), denoted as sZrO2, were synthesized and used as an additive to prepare anion exchange membranes (AEMs) based on 1-methylpyrrolidinium quaternized poly(2,6-dimethyl-1,4-phenylene oxide) (MPPO). The presence of the surfactant effectively improved the compatibility of the inorganic filler and the polymer matrix according to the morphology analysis. Compared to those of the MPPO membrane, the conductivities and tensile strengths of the composite membranes increased by 10–29% and 38–63%, respectively, benefiting from the presence of the sZrO2 and the leave-in surfactant CTAB. A hydroxide conductivity of 88.7 mS cm−1 was achieved in water at 80 °C by the MPPO-1.0 wt%sZrO2 membrane. Moreover, 74.2% of its initial conductivity were retained after immersed the membrane in 1 M KOH at 80 °C for 408 h. This membrane-based single fuel cell exhibited a peak power density of 515.6 mW cm−2 at 60 °C by fueling with humidified H2 and O2 with 0.1 MPa back pressure. More characterizations on the structures of associated materials by using FT-IR, 1H NMR, TEM, and X-Ray Diffraction were made as well.

Anion Exchange Membrane Based on Interpenetrating Polymer Network with Ultrahigh Ion Conductivity and Excellent Stability for Alkaline Fuel Cell.

A high-performance anion exchange membrane (AEM) is critical for the development of alkaline fuel cell. In this work, AEMs with an interpenetrating polymer network (IPN) are synthesized. An electron microscope clearly reveals a highly efficient “ion channel” network, which is constructed with a small amount of cation exchange groups. This specially designed ion channel leads to extraordinary hydroxide conductivity (e.g., 257.8 mS cm−1 at 80 °C) of IPN AEMs at moderate ion exchange capacity (IEC = 1.75 mmol g−1), as well as excellent long-term alkaline stability at harsh condition which showed that 81% of original conductivity can be retained after a long time for 1248 hours. Moreover, a remarkable peak power density of 1.20 W cm−2 (0.1 MPa backpressure) with nonprecious metal (FeNx-CNTs) as oxygen reduction reaction (ORR) catalyst in a fuel cell test was achieved. This work offers a general strategy to prepare high-performance AEMs based on IPN structure design.

Preparation and properties of anion exchange membranes with exceptional alkaline stable polymer backbone and cation groups

To study the effect of cation groups on the alkaline stability and other properties of anion exchange membranes (AEMs), common quaternary ammonium (QA), N-alicyclic quaternary ammonium and imidazolium cations with bulky substituents were grafted onto an aryl ether-free polyaromatic backbone synthesized via acid-catalyzed polyhydroxyalkylation. The size of cation groups is calculated by Gaussian. The size of bulky imidazolium (MIm) is much larger than QA and N-alicyclic quaternary ammonium (Py and Pi). Because of the large size of the cation groups, the chain entanglement density of AEM with bulky imidazolium (PFBA-MIm-0.4) is lower than other three membranes, resulting PFBA-MIm-0.4 displays the highest water uptake of 225.1% at 80 °C, whereas the IEC of PFBA-MIm-0.4 is the lowest (1.49 mmol g−1). Meanwhile, the toughness of the membranes decreases when the size of the cation group increases. AEM with common quaternary ammonium (PFBA-QA-0.4) exhibits the highest hydroxide conductivity of 142 mS cm−1 at 80 °C because it exhibits the highest ion exchange capacity (IEC). More interestingly, PFBA-QA-0.4 shows long term alkaline stability that is as good as that of the AEMs with alicyclic quaternary ammonium or bulky imidazolium, even in 5 mol L−1 aqueous NaOH at 80 °C; however, the small size of the substituents of common quaternary ammonium does not have steric hindrance that is as large as that of the substituents of alicyclic quaternary ammonium and bulky imidazolium. Therefore, we selected PFBA-QA-0.4 to prepare a membrane electrode assembly for the further study of alkaline H2/O2 fuel cell performance. The single H2/O2 fuel cell exhibits a peak power density as high as 559 mW cm−2 at 80 °C under 100% RH with 0.1 MPa backpressure. These results of the comparison of AEMs with different size cation groups give some insights for future directions in the development of advanced AEMs.

Poly(arylene piperidine)s with phosphoric acid doping as high temperature polymer electrolyte membrane for durable, high-performance fuel cells

The properties of high temperature polymer electrolyte membranes (HT-PEMs) are determined directly by the polymer matrix with phosphoric acid (PA) doping. Here, new polymer materials based on poly (arylene piperidine)s (PAPs) are prepared by one-step polymerization as PA absorbing matrix for HT-PEM fuel cells (HT-PEMFCs) application. The PAPs show excellent thermal stability and high glass transition temperature. Among PAPs, PA doped poly (N-methyl-piperidine-co-p-terphenyl) (PPT/PA) shows a high proton conductivity of 96.0 mS cm−1 at 180 °C without humidification and an excellent tensile strength of 12 MPa, which is much better than that of PA doped commercial poly [2,2’-(p-oxydiphenylene)-5,5′-benzimidazole] (OPBI/PA). The enhancement on conductivity of PPT/PA is attributed to the formation of micro-phase separation. A single cell based on PPT/PA membrane presents outstanding performance with a maximum power density of 1220.2 mW cm−2 with H2/O2 feeding under 0.15 MPa backpressure in cathode at 180 °C, which is 1.85 times of that with OPBI/PA membrane (660.8 mW cm−2). Furthermore, a H2/air single cell with PPT/PA shows excellent stability at a constant current density of 120 mAcm−2 and 150 °C for 1600 h. This work indicates PAPs (especially, PPT) are a promising PA doping polymer matrix for high temperature polymer electrolyte membrane fuel cells application.

Effect of Back Pressure on the Consolidation Behaviour of Titanium Sponge Particles Processed by ECAP

Titanium is a hard metal with good mechanical properties, corrosion resistant and biocompatibility which makes it have a wide range of applications (biomedical and aerospace). Severe plastic deformation (SPD) is employed to produce Ultrafine Grained (UFG) structures. UFG structures have better mechanical properties due to their compaction. Equal Channel Angular Pressing (ECAP) is adapted to produce a UFG structure in Titanium. In this process, titanium sponge powder is filled in the aluminium shell by intermediate tapping to fill the volume of the shell. The shell is then closed with an Al cap and ECAP is done with continuous back pressure at 300°C. The test specimen has undergone four passes in route BC at different back pressure (50, 100 and 150 MPa) where titanium is consolidated without any crack. Titanium showed decreased grain size and porosity with increasing backpressure. In particular, it is seen that the sample ECAPed by 100 MPa backpressure showed a relative density of about 98% with a hardness of 37 HRC. It is seen that ECAP is more economical and the product obtained by the ECAP process has better properties.

An annular-flow, hollow-fiber membrane chromatography device for fast, high-resolution protein separation at low pressure

High-resolution protein separation is currently carried out using columns packed with ultrafine particulate chromatographic media which can only be operated at very high pressures. This restricts the flow rate and thereby the speed of separation. A membrane with ultrafine pores shares the same mass transport advantages as a bed of ultrafine particles. However, application of membrane chromatography has largely been restricted to low-resolution separation applications, primarily due to limitations associated with poorly designed devices. In this paper, we describe a novel annular-flow hollow-fiber membrane chromatography (AHMC) device, suitable for fast, high-resolution protein separation. The AHMC device was designed primarily from a fluidics perspective to ensure a narrow solute residence time distribution, a low dead-volume, and minimal fluid back-mixing. Using this device, it was possible to separate a ternary protein mixture in less than a minute, at less than 0.3 MPa backpressure. The high-resolution separation capability of AHMC was further demonstrated through its use for the separation of bovine serum albumin (BSA) dimer from the monomeric form of the protein. This was achieved in less than 3 min which was considerably faster than other reported techniques for protein aggregates separation.

Separation and purification of compounds from piper kadsura using preparative reversed-phase liquid chromatography and preparative supercritical fluid chromatography

A method based on preparative reversed-phase liquid chromatography (prep-RPLC) and preparative supercritical fluid chromatography (prep-SFC) was developed for the separation and purification of compounds from piper kadsura. A pretreatment method was first developed, including methanol extraction, water precipitation, petroleum ether extraction, etc. Chlorophyll and other strong polar impurities were removed from the piper kadsura samples, and the target components were enriched in petroleum ether extracts. The piper kadsura samples were separated into 18 fractions on a Unitary C18 column (250 mm×20 mm, 5 μm) with water and methanol as the mobile phases. Then, the SFC parameters, including the column, modifier, temperature, and backpressure were optimized. The optimized conditions for prep-SFC were as follows:XAmide column (250 mm×20 mm, 5 μm), methanol as the modifier, 30℃ column temperature, and 15.0 MPa backpressure. Because of the good orthogonality of RPLC and SFC, six highly pure compounds were isolated, including kadsurenone, wallichinine, denudatin B, pellitorine, 2E-decenoic acid N-isobutylamide, and futoxide.

Pore-Scale Studies on the Stability of Microfoam and the Effect of Parameters on Its Bubble Size

This paper presents a new method to prepare microfoam with excellent stability and high by using a sandpack foam generator. The micromorphology of microfoam were analyzed, and average bubble diameter and uniformity of microfoam were studied by microscope. The stability of xanthan gum-stabilized microfoam and common microfoam at the pore scale was also compared. The results showed that a highly uniform microfoam ranging in size from 10 to 100 µm in diameter with a variable coefficient less than 10% was successfully prepared. The bubble size of the microfoam could be controlled by solution viscosity, gas and liquid flow rate, temperature, and backpressure. The bubble size of microfoam decreased and became uniform with the increase of solution viscosity, total flow rate, and backpressure. The bubble size increased slightly and became non-uniform with the increase of temperature, while the concentration of foaming agent had little effect on the bubble size when above 5000 mg/L. The xanthan gum in the solution increased the viscosity and thickness of liquid membrane, so xanthan gum-stabilized microfoam maintained better stability within microconfined media than common microfoam under condition of 160 g/L salinity, 90°C, and 6 MPa backpressure.

Hydrogen storage properties of rare earth (RE) borohydrides (RE = La, Er) in composite mixtures with LiBH4 and LiH

Mixtures of 6LiBH4–RECl3–3LiH (RE=La, Er) have been produced by mechanochemical milling and their structure, thermal decomposition and reversibility have been studied. Hydrogen desorption starts around 300°C in both composites. Heating to 400°C yields LaB6, ErB4 and REH2+δ as major decomposition products. LiBH4 is destabilized by REH2+δ formed through decomposition of the parent borohydrides LiLa(BH4)3Cl and Er(BH4)3, respectively, and its hydrogen release temperature is reduced by 100°C as compared to pure ball-milled LiBH4. The lanthanum-containing composite releases 4.2wt.% H between 300 and 350°C and shows a limited reversibility of ∼20% (340°C, 10MPa) probably due to hydrogen uptake by some amorphous boron-containing phases. For 6LiBH4–ErCl3–3LiH about 3wt.% H is evolved up to 400°C. Desorption against 0.5MPa backpressure results in an increased reversibility (∼80%) as compared to vacuum (∼66%). Rehydrogenation (340°C, 10MPa) shows the formation of ErH3 and LiBH4 at drastically reduced conditions compared to pure LiBH4 (>400°C, >10MPa).

Study on Controlling Lost Circulation of Pilot Hole in Raise Boring by Using Fuzzy Ball Drilling Fluid

The fuzzy drilling fluid can effectively solve the serious lost circulation problem in the surface layer, it can be used in the raise drilling. The fuzzy ball drilling fluid with the density of 0.9g/cm3 was prepared in the laboratory. With the driving pressure increases, researchers do the plugging experiment with & without 0.5MPa back pressure. The experiments show that in a back pressure condition, fuzzy ball drilling fluid can effectively plugging formation. Besides, fuzzy ball drilling fluid can effectively control the leakage without back pressure. In the process of GuiZhou LongAn raise boring, the surface layer of the hole leaked seriously with leak off rate of more than 40m3/h in the first 10m and once exceeded 100 m3/h.The field use Fuzzy ball drilling fluid on the well plugging. The circulation is rapidly established after the Fuzzy ball drilling fluid was injected into the well, and the leakage rate has been effectively controlled.In the raise drilling, the fuzzy ball drilling fluid can only control the leakage rate but can’t seal the leakage formation.

Characterization of stationary phases based on polysiloxanes thermally immobilized onto silica and metalized silica using supercritical fluid chromatography with the solvation parameter model

Stationary phases (SP) prepared by immobilization of polymers on silica or metalized silica are interesting for use in reversed-phase high-performance liquid chromatography (RP-HPLC) due to better protection of residual silanols or Lewis acid sites, as well as ease of preparation. On the other hand, there are no previous reports of the use of such phases in packed column supercritical fluid chromatography (SFC). Fourteen different SPs based on polysiloxanes (phenyl, C1, C8, C14, C18) thermally immobilized onto different supports (silica, titanized silica, zirconized silica) and one chemically bonded and end-capped C18 stationary phase having a doubly zirconized silica support, were characterized with identical SFC conditions (CO2 with 10% of methanol, 25°C, 15.0MPa backpressure). Characterization was achieved based on retention factors measured for 85 test compounds and linear solvation energy relationships (LSER), namely the solvation parameter model based on Abraham descriptors. The polysiloxane SP were compared to a commercial C18-bonded silica (Kromasil C18), and to the native silica and metalized silica supports to better unravel the effects of stationary phase chemistry on chromatographic behavior. Together, 19 stationary phases were compared. The results highlight the variety of polarities provided by the column set. The polysiloxane backbone contributes significantly to the SP polarity as evidenced by the comparison to a classical alkylsiloxane-bonded SP. Metalization also appears to modify the polar characteristics of the SP, particularly toward basic compounds. Sample applications illustrate the applicability of these SP in SFC to the analysis of compounds of interest to the pharmaceutical and cosmetic industries.