Solid Phase Extraction (SPE) is one of the most highly selective sample preparation methods, meaning that the targeted analytes and their matrices must be considered when choosing the correct SPE sorbent and format. Drying down the sorbent before elution is an important step.<ul><li>Wash solvents are used to flush out unwanted compounds (i.e., contaminants). If the wash solvent is not completely removed, then residual wash solvent could contaminate the final elution.</li><li>If you do not dry the SPE sufficiently, it could make the final solution less concentrated and result in a reduction in sensitivity.</li><li>Drying helps physically break down the interactions between the sorbent and analyte for a more concentrated extract.</li></ul>After the wash solvent has been passed through the cartridge, continue to apply negative pressure (vacuum) or positive pressure. Use this pressure to dry the cartridge for 2 to 5 minutes (or until dry). Turn off the pressure and wipe the tips of the manifold needles to remove any residual solvent.<h5>Notes</h5><ol><li>Reproducibility: Drying removes traces of residual sample/matrix and wash solvent from the sorbent. This produces a more concentrated final extract with a consistent volume and composition and yields better reproducibility and higher recoveries.</li><li>Immiscibility: Drying is especially critical when using elution solvents that are immiscible with water (e.g. hexane, ethyl acetate, and methylene chloride). Residual water in the sorbent bed may prevent dissolution of the analyte in the elution solvent, resulting in low recoveries and irreproducibility.</li><li>Over-drying: Avoid over-drying the sorbent, since in some cases, analyte recovery may decrease with excessive vacuum or drying times above 5 minutes. Dry cartridges look distinctly different from moist ones. Make a note of the cartridge appearance before and after conditioning. Also, you could touch the cartridge while it is drying; wet cartridges feel colder than dry cartridges.&nbsp;</li></ol>

Why Is It Necessary to Dry the SPE Sorbent Before Elution?

<h3>Mastering Ion-Pair Reversed-Phase Chromatography for Oligonucleotide Analysis</h3><h4>Why Purity Is Critical in the Oligonucleotide Era</h4>Oligonucleotides — short, synthetic strands of DNA or RNA — are central to modern biotechnology. They power gene therapies, advanced diagnostics, and cutting-edge molecular research. However, before these molecules can be used in clinical or research settings, their purity and structural integrity must be thoroughly verified. High-resolution chromatographic analysis plays a crucial role in ensuring quality and safety.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Figure_1_Separation_Example_of_Oligonucleotides_5577514561.jpg" alt="KNAUER: Figure 1 - Separation Example of Oligonucleotides." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Figure_1_Separation_Example_of_Oligonucleotides_5577514561.jpg 245w," sizes="100vw" width="1024" height="368"><h4>Understanding Ion-Pair Reversed-Phase (IP-RP) Chromatography</h4>For scientists involved in oligonucleotide synthesis and characterization, Ion-Pair Reversed-Phase Chromatography (IP-RP) is one of the most effective analytical tools available.Unlike separation techniques that rely solely on charge differences, IP-RP combines:<ul><li>Ionic interactions</li><li>Hydrophobic interactions</li></ul>This dual retention mechanism enables exceptional resolution — even for oligonucleotides that differ by only a single nucleotide or subtle chemical modification. Whether assessing synthesis efficiency or purifying therapeutic-grade material, IP-RP provides reliable, reproducible separations.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Figure_2_Overview_of_IP_RP_Mode_prinicple_ecd54b6e9c.jpg" alt="KNAUER: Figure 2 - Overview of IP-RP Mode prinicple." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Figure_2_Overview_of_IP_RP_Mode_prinicple_ecd54b6e9c.jpg 245w," sizes="100vw" width="1024" height="456"><h4>The Principle Behind Ion-Pairing</h4>Oligonucleotides possess a highly negatively charged phosphate backbone. In a traditional reversed-phase system, such hydrophilic, charged molecules would show little retention.IP-RP overcomes this limitation by introducing a positively charged ion-pairing reagent into the mobile phase. The cation associates with the negatively charged oligonucleotide, forming a transient ion pair with increased hydrophobic character. This modified complex can now interact with the hydrophobic stationary phase.Retention strength depends on:<ul><li>The hydrophobicity of the ion-pair reagent</li><li>The strength of ionic interaction</li><li>The applied organic gradient</li></ul>During gradient elution (commonly using acetonitrile), analytes are released in a controlled manner according to size, sequence, and chemical modifications.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Figure_3_Ion_Pair_Reversed_Phase_Principle_9a4fcd12f2.jpg" alt="KNAUER: Figure 3 - Ion-Pair Reversed Phase Principle." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Figure_3_Ion_Pair_Reversed_Phase_Principle_9a4fcd12f2.jpg 245w," sizes="100vw" width="1024" height="393"><h4>Choosing the Right Ion-Pair Reagent</h4>Successful IP-RP separation depends heavily on selecting an appropriate ion-pair reagent. Two key factors determine retention behavior:<ol><li>Alkyl chain length</li><li>Charge density</li></ol><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Figure_4_Ion_Pair_Classification_eaad172a4e.jpg" alt="KNAUER: Figure 4 - Ion-Pair Classification." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Figure_4_Ion_Pair_Classification_eaad172a4e.jpg 245w," sizes="100vw" width="1024" height="398"><h4>Strong Cationic Ion-Pair Reagents</h4>Ion-pair reagents with longer alkyl chains provide stronger hydrophobic interactions and increased retention. A widely used example is tetrabutylammonium (TBA⁺), frequently applied for strongly retained anionic analytes.These reagents are particularly useful when high retention strength is required.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Table_1_Strong_Cationic_Ion_Pair_Reagents_8dbf00c57e.jpg" alt="KNAUER: Table 1 - Strong Cationic Ion-Pair Reagents." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Table_1_Strong_Cationic_Ion_Pair_Reagents_8dbf00c57e.jpg 245w," sizes="100vw" width="1024" height="396"><h4>Volatile (Weaker) Ion-Pair Reagents</h4>Short-chain ion-pair reagents generate weaker retention but offer a significant advantage: compatibility with LC–MS detection.Triethylammonium (TEA⁺) is among the most commonly used reagents for oligonucleotide analysis, particularly when mass spectrometric detection is involved. Other options, such as diisopropylethylammonium (DIEA⁺), are also widely applied, often combined with HFIP to enhance MS performance.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Table_2_Weak_Cationic_Ion_Pair_Reagents_6332a4975e.jpg" alt="KNAUER: Table 2 - Weak Cationic Ion-Pair Reagents." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Table_2_Weak_Cationic_Ion_Pair_Reagents_6332a4975e.jpg 245w," sizes="100vw" width="1024" height="283"><h4>Building an IP-RP Method for Oligonucleotides</h4>Developing a robust IP-RP method follows a logical sequence:<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Table_3_IP_RP_Method_Step_Procedure_for_Oligos_c2216c24a0.jpg" alt="KNAUER: Table 3 - IP-RP Method Step Procedure for Oligos." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Table_3_IP_RP_Method_Step_Procedure_for_Oligos_c2216c24a0.jpg 245w," sizes="100vw" width="1024" height="304"><h5>1. Characterize the Analyte</h5>Oligonucleotides typically contain 10–50+ nucleotides and exhibit high negative charge density. This necessitates a suitable cationic partner such as TEA⁺ or DIEA⁺.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Figure_5_Cationic_Ion_Pair_Principle_for_Oligonucleotides_cb2dfb7457.jpg" alt="KNAUER: Figure 5 - Cationic Ion-Pair Principle for Oligonucleotides." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Figure_5_Cationic_Ion_Pair_Principle_for_Oligonucleotides_cb2dfb7457.jpg 245w," sizes="100vw" width="512" height="320"><h5>2. Select the Column</h5>Use a reversed-phase column with:<ul><li>Large pore size (≈300 Å)</li><li>Appropriate internal diameter</li></ul>These parameters support the so-called “ON–OFF” retention mechanism — a bind-and-elute behavior where analytes are strongly retained until the gradient triggers rapid elution.<h5>3. Optimize the Mobile Phase</h5>A typical starting condition includes:<ul><li>10 mM TEA buffer at pH ~7</li><li>Acetonitrile as organic modifier</li></ul>Gradient programs from approximately 5% to 50% organic solvent over 15–30 minutes are commonly effective for complex oligonucleotide mixtures.<h5>4. Adjust Retention Strength if Needed</h5>To increase retention:<ul><li>Raise ion-pair concentration (up to ~100 mM if required)</li><li>Select a more hydrophobic ion-pair reagent</li></ul><h5>5. Validate the Method</h5>Ensure robustness, sensitivity, and reproducibility by carefully evaluating:<ul><li>UV chromatograms</li><li>MS traces</li><li>Peak shape and resolution</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Figure_6_UV_MS_traces_of_IP_RP_Oligonucleotide_Analysis_81faf4e9f0.jpg" alt="KNAUER: Figure 6 - UV-MS traces of IP-RP Oligonucleotide Analysis." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Figure_6_UV_MS_traces_of_IP_RP_Oligonucleotide_Analysis_81faf4e9f0.jpg 245w," sizes="100vw" width="1024" height="365"><h4>Why IP-RP Is Considered the Gold Standard</h4>Ion-Pair Reversed-Phase Chromatography uniquely combines the resolving power of reversed-phase LC with the ability to retain highly polar, charged biomolecules.Its advantages include:<ul><li>Tunable selectivity</li><li>Compatibility with UV and MS detection</li><li>Scalability from analytical to preparative workflows</li><li>Applicability from research to pharmaceutical production</li></ul>By transforming highly charged oligonucleotides into hydrophobic ion-pair complexes, IP-RP enables precise and reproducible separations that would otherwise be impossible in conventional reversed-phase systems.For these reasons, IP-RP is widely regarded as the benchmark technique for oligonucleotide analysis.<h4>Final Thoughts</h4>Mastering IP-RP is less intimidating than it may seem. A successful method comes down to:<ul><li>Selecting the right ion-pair reagent</li><li>Choosing a suitable column</li><li>Optimizing gradient conditions</li><li>Fine-tuning temperature and concentration parameters</li></ul>With thoughtful method development, IP-RP delivers sharp peaks, clean separations, and reliable performance — fully compatible with modern mass spectrometry workflows and ready to meet the demands of advanced oligonucleotide analysis.

Oligos Made Easy - Part 3: IP-RP

News from LabRulezLCMS Library - Week 08, 2026

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Phenomenex is a global technology leader committed to developing novel analytical chemistry solutions that solve the separation and purification challenges of researchers in industrial, government and academic laboratories.

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Based in Berlin, KNAUER is a medium-sized, owner-managed company that has been serving the sciences since 1962. We develop and manufacture scientific instruments of superior quality for liquid chromatography, including: Analytical HPLC/UHPLC, Preparative HPLC, Fast protein liquid chromatography (FPLC), Multi-column chromatography/Simulated moving bed (SMB) chromatography. High pressure dosing, in-line detection systems, and osmometry are additional business areas.

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KNAUER Eurospher II 100 C4 (U)HPLC Columns (USP L26)

C4 stationary phases (USP L26) are often used in reversed phase mode for different application areas. 

C4 columns for Reversed Phase in HPLC and UHPLC (USP L26)C4 stationary phases (USP L26) are often used in reversed phase mode for different application areas.&nbsp;They are suitable for:<ul><li>Hydrophobic Interaction Chromatography (HIC mode)</li><li>Analysis of biomolecules like proteins and peptides</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_C4_3f3adfbdb4.webp" alt="KNAUER: C4" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_C4_3f3adfbdb4.webp 78w," sizes="100vw" width="200" height="400"><h3>KNAUER (U)HPLC Columns</h3>Widest range of HPLC and UHPLC columns for all separation modes and applications.<ul><li>Safe Investment: Robust and reliable columns for attractive price&nbsp;</li><li>Separation Mode: Reversed Phase, HILIC, Normale</li><li>Simplicity: Easy purchase via our online store with fast delivery</li><li>Application: All-rounder for research or highly specialised for high-throughput analysis? We have the best column for your requirements.</li><li>Flexibility: Wide selection of column and particle sizes, for (U)HPLC applications up to 1000 bar</li></ul>KNAUER offers the perfect column for any small molecule separation. No matter which separation mode, molecule and the mobile phase, we offer a suitable (U)HPLC stationary phase. Choose from a wide range of modifications, particle sizes and column dimensions to suit your application. To elongate the lifetime of your column, you can choose to use a suitable precolumn.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp" alt="KNAUER: KNAUER (U)HPLC Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp 182w," sizes="100vw" width="787" height="674">

KNAUER Eurospher II 100 CN (U)HPLC Columns for NP & RP (USP L10)

CN is one of the most versatile stationary phases that can be used in reversed phase mode as well as in normal phase mode. 

Cyano or CN for Normal Phase and Reversed Phase (USP L10)CN is one of the most versatile stationary phases that can be used in reversed phase mode as well as in normal phase mode. The cyano modification supports the π-π interaction as well as polar and hydrophobic interactions with low polarity solvents. These phases are preferred for compounds with double bonds and aromatic groups. Cyano bonded phases show unique selectivity for polar compounds and are more suitable than bare silica for normal phase (NP) gradient separations. The cyano functional group is a strong dipole that can interact with other dipoles or induce dipoles on solutes. These phases also exhibit moderate hydrophobicity due to the alkyl linker.Due to the quick equilibration time of the CN bonded phase, it is the best choice for gradient elution in normal phase mode. CN phases can be used as a less polar alternative to Si phases.The material is typically preferred for:<ul><li>Compounds with double bonds</li><li>Cyclic antidepressants</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_CN_4fff7a1e28.webp" alt="KNAUER: CN" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_CN_4fff7a1e28.webp 130w," sizes="100vw" width="358" height="428"><blockquote>Stationary phase Eurospher II 100 CN is provided in these column types: analytical, semi-preparative and preparative.</blockquote>Eurospher II 100 CN Analytical Columns are available with these parameters:<ul><li>Column length (mm): 50, 100, 150, 250</li><li>Column ID (mm): 3, 4, 4.6</li><li>Particle size (µm): 3, 5</li></ul>Eurospher II 100 CN Semi-Preparative Standard Columns are available with these parameters:<ul><li>Column length (mm): 30, 50, 125, 150, 250</li><li>Column ID (mm): 8, 16</li><li>Particle size (µm): 5, 10</li></ul><h3>KNAUER (U)HPLC Columns</h3>Widest range of HPLC and UHPLC columns for all separation modes and applications.<ul><li>Safe Investment: Robust and reliable columns for attractive price&nbsp;</li><li>Separation Mode: Reversed Phase, HILIC, Normale</li><li>Simplicity: Easy purchase via our online store with fast delivery</li><li>Application: All-rounder for research or highly specialised for high-throughput analysis? We have the best column for your requirements.</li><li>Flexibility: Wide selection of column and particle sizes, for (U)HPLC applications up to 1000 bar</li></ul>KNAUER offers the perfect column for any small molecule separation. No matter which separation mode, molecule and the mobile phase, we offer a suitable (U)HPLC stationary phase. Choose from a wide range of modifications, particle sizes and column dimensions to suit your application. To elongate the lifetime of your column, you can choose to use a suitable precolumn.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp" alt="KNAUER: KNAUER (U)HPLC Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp 182w," sizes="100vw" width="787" height="674">

KNAUER Eurospher II 100 DNPH (U)HPLC Columns (USP L1)

Silica gel based columns with C18 modification with special endcapping, designed for DNPH analysis.

DNPH columns for polar reversed phase applications with 100 % aqueous mobile phase (USP L1)C18 stationary phase for the analysis of more polar and hydrophilic compounds in reversed phase mode (USP L1). Silica gel based columns with C18 modification with special endcapping, designed for DNPH analysis. Because of their modification, DNPH phases can be operated under 100 % aqueous conditions without destroying the stationary phase, what is not recommended for classical C18 phases caused by their hydrophobicity.These phases are ideal for the analysis of:<ul><li>DNPH-derivates of aldehydes and ketones</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_DNPH_7020417932.webp" alt="KNAUER: DNPH" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_DNPH_7020417932.webp 245w," sizes="100vw" width="690" height="428"><h3>KNAUER (U)HPLC Columns</h3>Widest range of HPLC and UHPLC columns for all separation modes and applications.<ul><li>Safe Investment: Robust and reliable columns for attractive price&nbsp;</li><li>Separation Mode: Reversed Phase, HILIC, Normale</li><li>Simplicity: Easy purchase via our online store with fast delivery</li><li>Application: All-rounder for research or highly specialised for high-throughput analysis? We have the best column for your requirements.</li><li>Flexibility: Wide selection of column and particle sizes, for (U)HPLC applications up to 1000 bar</li></ul>KNAUER offers the perfect column for any small molecule separation. No matter which separation mode, molecule and the mobile phase, we offer a suitable (U)HPLC stationary phase. Choose from a wide range of modifications, particle sizes and column dimensions to suit your application. To elongate the lifetime of your column, you can choose to use a suitable precolumn.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp" alt="KNAUER: KNAUER (U)HPLC Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp 182w," sizes="100vw" width="787" height="674">

KNAUER Eurospher II 100 Diol (U)HPLC Columns for NP (USP L20)

Diol packing material can be universally used in different polar modes (NP, RP and HILIC). Diol bonded phases are a versatile alternative to unbonded silica for normal phase separations.

Diol columns for Normal Phase in HPLC and UHPLC (USP L20)Diol packing material can be universally used in different polar modes (NP, RP and HILIC). Diol bonded phases are a versatile alternative to unbonded silica for normal phase separations with shorter equilibration times.The hydroxyl groups provide good selectivity without excessive retention, caused by the weaker H-bonding of the diol layer than of silanols. Some diol bonded phases have been developed specifically for applications in the HILIC mode.<h5>Properties</h5><ul><li>Separation mechanism: Hydrophilic interaction</li><li>Ultra pure, spherical high performance HPLC phase based on silica gel</li><li>Diol, no endcapping, with 5 % carbon content&nbsp;</li></ul><h5>Key features</h5><ul><li>High-class HPLC phase perfectly suited to take on routine analyses as well as the most ambitious chromatography tasks, classical Diol phase without endcapping and 5 % carbon content, outstanding mechanical and chemical stability.</li></ul><h5>Recommended application areas</h5><ul><li>Alternative to the silica packing with shorter equilibration time and comparable selectivity; due to the lower activity of these packings it can be also used for SEC-applications.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Diol_26fe64c2b9.webp" alt="KNAUER: Diol" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Diol_26fe64c2b9.webp 156w," sizes="100vw" width="426" height="425"><blockquote>Tip: The most important column parameters for evaluation are retention time, peak symmetry and theoretical plates. Retention time to prove the reproducibility of measurements. Peak symmetry to estimate how good the column bed is packed (peak symmetry value of 1.0 is optimal). Theoretical plate numbers to determine the effectiveness of the HPLC column.</blockquote>Stationary phase Eurospher II 100 Diol is provided in these column types: analytical, semi-preparative and preparative.Eurospher II 100 Diol Analytical Columns are available with these parameters:<ul><li>Column length (mm): 50, 100, 150, 250</li><li>Column ID (mm): 3, 4, 4.6</li><li>Particle size (µm): 3, 5</li></ul>Eurospher II 100 Diol Semi-Preparative Standard Columns are available with these parameters:<ul><li>Column length (mm): 30, 50, 125, 150, 250</li><li>Column ID (mm): 8, 16</li><li>Particle size (µm): 5, 10</li></ul><h3>KNAUER (U)HPLC Columns</h3>Widest range of HPLC and UHPLC columns for all separation modes and applications.<ul><li>Safe Investment: Robust and reliable columns for attractive price&nbsp;</li><li>Separation Mode: Reversed Phase, HILIC, Normale</li><li>Simplicity: Easy purchase via our online store with fast delivery</li><li>Application: All-rounder for research or highly specialised for high-throughput analysis? We have the best column for your requirements.</li><li>Flexibility: Wide selection of column and particle sizes, for (U)HPLC applications up to 1000 bar</li></ul>KNAUER offers the perfect column for any small molecule separation. No matter which separation mode, molecule and the mobile phase, we offer a suitable (U)HPLC stationary phase. Choose from a wide range of modifications, particle sizes and column dimensions to suit your application. To elongate the lifetime of your column, you can choose to use a suitable precolumn.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp" alt="KNAUER: KNAUER (U)HPLC Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp 182w," sizes="100vw" width="787" height="674">

KNAUER Eurospher II 100 Phenyl (U)HPLC Columns for RP (USP L11)

Phenyl stationary phases (USP L11) in reversed phase mode with alternative selectivity for aromatic and moderately π-π interaction polar analytes

Phenyl columns for Reversed Phase in HPLC and UHPLC &nbsp;(USP L11)Phenyl stationary phases (USP L11) in reversed phase mode with alternative selectivity for:<ul><li>Aromatic and moderately π-π interaction polar analytes</li><li>Mixtures with varying polarity and aromaticity</li></ul>The polarity is similar to C8 modification but with different selectivity for polar aromatics, polycyclic aromatic hydrocarbons, fatty acids etc. Phenyl phases with a classical slightly hydrophobic endcapping or without endcapping.<h5>Properties</h5><ul><li>Separation mechanism: π-π interactions</li><li>Ultra pure, spherical high performance HPLC phase based on silica gel</li><li>Phenyl modification (Phenylpropyl), 12 % carbon content</li></ul><h5>Key features</h5><ul><li>Classical phenyl phase with 12 % carbon load, outstanding mechanical and chemical stability, suited for analytical as well as semi preparative and preparative applications.</li></ul><h5>Recommended application areas</h5><ul><li>Alternative selectivity for aromatic and mode rately pi-pi interaction polar analytes or mixtures with varying polarity and aromaticity.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Phenyl_df9b20c77a.webp" alt="KNAUER: Phenyl" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Phenyl_df9b20c77a.webp 90w," sizes="100vw" width="306" height="528"><blockquote>Tip: For UHPLC columns like Eurospher II 2 μm particle size, samples and eluents should be filtered through a 0.2 μm instead of a 0.45 μm membrane filter. Frits at column inand outlet have smaller pores than classical HPLC columns and block more easily.</blockquote>Stationary phase Eurospher II 100 Phenyl is provided in these column types: analytical, semi-preparative and preparative.Eurospher II 100 Phenyl Analytical Columns are available with these parameters:<ul><li>Column length (mm): 50, 100, 150, 250</li><li>Column ID (mm): 2, 3, 4, 4.6</li><li>Particle size (µm): 2, 3, 5</li></ul>Eurospher II 100 Phenyl Semi-Preparative Standard Columns are available with these parameters:<ul><li>Column length (mm): 30, 50, 125, 150, 250</li><li>Column ID (mm): 8, 16</li><li>Particle size (µm): 5, 10</li></ul><h3>KNAUER (U)HPLC Columns</h3>Widest range of HPLC and UHPLC columns for all separation modes and applications.<ul><li>Safe Investment: Robust and reliable columns for attractive price&nbsp;</li><li>Separation Mode: Reversed Phase, HILIC, Normale</li><li>Simplicity: Easy purchase via our online store with fast delivery</li><li>Application: All-rounder for research or highly specialised for high-throughput analysis? We have the best column for your requirements.</li><li>Flexibility: Wide selection of column and particle sizes, for (U)HPLC applications up to 1000 bar</li></ul>KNAUER offers the perfect column for any small molecule separation. No matter which separation mode, molecule and the mobile phase, we offer a suitable (U)HPLC stationary phase. Choose from a wide range of modifications, particle sizes and column dimensions to suit your application. To elongate the lifetime of your column, you can choose to use a suitable precolumn.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp" alt="KNAUER: KNAUER (U)HPLC Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp 182w," sizes="100vw" width="787" height="674">

KNAUER Eurospher II 100 HILIC (U)HPLC Columns

Based on ultra-pure Silica gel, zwitterionic HILIC phases are ideal for the analysis of polar and ionizable compounds. Stronger interaction of more polar compounds with stationary aqueous layer.

Zwitterionic and polar columns for HILIC applicationsBased on ultra-pure Silica gel, zwitterionic HILIC phases are ideal for the analysis of polar and ionizable compounds. Stronger interaction of more polar compounds with stationary aqueous layer.Faster elution of nonpolar compounds is possible due to minor hydrophobic interactions. Retention increases with the charge of the analyte.<h5>Recommended for the analysis of hydrophilic compounds like:</h5><ul><li>Polar organic acids and bases</li><li>Natural polar compounds</li><li>Nucleosides</li><li>Oligonucleotides</li><li>Amino acids</li><li>Peptides</li><li>Water soluble vitamins</li></ul><h5>Properties</h5><ul><li>Separation mechanism: Hydrophilic and weak electrostatic interactions</li><li>Ultra pure, spherical high performance HPLC phase based on silica gel</li><li>Zwitterionic modification: Ammonium – sulfonic acid</li><li>7 % carbon content</li></ul><h5>Key features</h5><ul><li>Modern HILIC phase with zwitterionic modification on the basis of ammonium- sulfonic acid. Outstanding mechanical and chemical stability.</li></ul><h5>Recommended application areas</h5><ul><li>Especially suited for the separation of hydrophilic, polar and ionic analytes which are poorly retained on reversed phase columns; behavior is the other way round on Eurospher II HILIC compared to RP which makes it an ideal tool to enhance chromatographic separations for these molecules.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_HILIC_b9c3bffc20.webp" alt="KNAUER: HILIC" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_HILIC_b9c3bffc20.webp 147w," sizes="100vw" width="439" height="465"><blockquote>Tip: HILIC applications are well-suited for coupling with MS detection. The high organic content of the applied mobile phases are qualified well for evaporation in the MS´s ionization source.</blockquote>Stationary phase Eurospher II 100 HILIC is provided in these column types: analyticalEurospher II 100 HILIC Analytical Columns are available with these parameters:<ul><li>Column length (mm): 50, 100, 150, 250</li><li>Column ID (mm): 3, 4, 4.6</li><li>Particle size (µm): 3, 5</li></ul><h3>KNAUER (U)HPLC Columns</h3>Widest range of HPLC and UHPLC columns for all separation modes and applications.<ul><li>Safe Investment: Robust and reliable columns for attractive price&nbsp;</li><li>Separation Mode: Reversed Phase, HILIC, Normale</li><li>Simplicity: Easy purchase via our online store with fast delivery</li><li>Application: All-rounder for research or highly specialised for high-throughput analysis? We have the best column for your requirements.</li><li>Flexibility: Wide selection of column and particle sizes, for (U)HPLC applications up to 1000 bar</li></ul>KNAUER offers the perfect column for any small molecule separation. No matter which separation mode, molecule and the mobile phase, we offer a suitable (U)HPLC stationary phase. Choose from a wide range of modifications, particle sizes and column dimensions to suit your application. To elongate the lifetime of your column, you can choose to use a suitable precolumn.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp" alt="KNAUER: KNAUER (U)HPLC Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp 182w," sizes="100vw" width="787" height="674">

KNAUER Eurospher II 100 NH2 (U)HPLC Columns for NP & HILIC (USP L8)

Amino (NH2) bonded silica gel phases can be used in the normal phase (NP) and HILIC mode, but also for reversed phase (RP) mode.

Amino columns for Normal Phase and for HILIC applications (USP L8)Amino (NH2) bonded silica gel phases can be used in the normal phase (NP) and HILIC mode, but also for reversed phase (RP) mode. They show alternative normal phase selectivity to unbonded silica, especially for aromatics. Furthermore, the selectivity is influenced by hydrogen bond interactions with the analyte. Amino columns can also be used in the HILIC mode for carbohydrate analysis and for other polar compounds. Their weak anion-exchange properties can be used in the analysis of anions and organic acids.The amino group is bonded to the silica support via a propyl linker.<h5>Properties</h5><ul><li>Separation mechanism: Hydrophilic and ionic interactions</li><li>Ultra pure, spherical high performance HPLC phase based on silica gel</li><li>Amino modification (Aminopropyl)</li><li>4 % carbon content (without endcapping)</li></ul><h5>Key features</h5><ul><li>Multi mode column for RP, NP, HILIC and IC, Aminopropyl modification without endcapping, outstanding mechanical and chemical stability.</li></ul><h5>Recommended application areas</h5><ul><li>Most flexible phase in the Eurospher II family; can be used in three modes: normal phase, reversed phase and ion chromatography mode (weak anion exchanger); different selectivity to the silica packing; in reversed phase mode mainly used for analysis of carbohydrates.&nbsp;</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_NH_2_HILIC_NP_fbaa6027c0.webp" alt="KNAUER: NH2" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_NH_2_HILIC_NP_fbaa6027c0.webp 107w," sizes="100vw" width="290" height="421"><blockquote>Tip: A precolumn can help to protect your analytical column. Especially when working with highly matrix afflicted samples it is highly recommended to use precolumns.</blockquote>Stationary phase Eurospher II 100 NH2 is provided in these column types: analytical, semi-preparative and preparative.Eurospher II 100 NH2 Analytical Columns are available with these parameters:<ul><li>Column length (mm): 50, 100, 150, 250</li><li>Column ID (mm): 3, 4, 4.6</li><li>Particle size (µm): 3, 5</li></ul>Eurospher II 100 NH2 Semi-Preparative Standard Columns are available with these parameters:<ul><li>Column length (mm): 30, 50, 125, 150, 250</li><li>Column ID (mm): 8, 16</li><li>Particle size (µm): 5, 10</li></ul><h3>KNAUER (U)HPLC Columns</h3>Widest range of HPLC and UHPLC columns for all separation modes and applications.<ul><li>Safe Investment: Robust and reliable columns for attractive price&nbsp;</li><li>Separation Mode: Reversed Phase, HILIC, Normale</li><li>Simplicity: Easy purchase via our online store with fast delivery</li><li>Application: All-rounder for research or highly specialised for high-throughput analysis? We have the best column for your requirements.</li><li>Flexibility: Wide selection of column and particle sizes, for (U)HPLC applications up to 1000 bar</li></ul>KNAUER offers the perfect column for any small molecule separation. No matter which separation mode, molecule and the mobile phase, we offer a suitable (U)HPLC stationary phase. Choose from a wide range of modifications, particle sizes and column dimensions to suit your application. To elongate the lifetime of your column, you can choose to use a suitable precolumn.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp" alt="KNAUER: KNAUER (U)HPLC Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp 182w," sizes="100vw" width="787" height="674">

KNAUER Eurospher II 100 Si (U)HPLC Columns for NP & HILIC (USP L3)

Unmodified Silica gel materials were the first ones used for chromatography. This is the reason the mode is called "normal phase" (NP).

Si columns for Normal Phase and HILIC applications (USP L3)Unmodified Silica gel materials were the first ones used for chromatography. This is the reason the mode is called "normal phase" (NP). They are still used in HPLC, although reversed phase (RP) is by far the most often used HPLC mode today.<h5>A wide range of porous Si materials are available, characterized by:</h5><ul><li>Surface area</li><li>Pore size</li><li>Particle size</li><li>Purity</li><li>Metal content</li></ul><h5>Properties</h5><ul><li>Separation mechanism: Hydrophilic interactions</li><li>Ultra pure, spherical high performance HPLC phase based on silica gel</li><li>No modification, no endcapping, with 0 % carbon content</li></ul><h5>Key features</h5><ul><li>High-class HPLC phase perfectly suited to take on routine analyses as well as the most ambitious chromatography tasks, outstanding mechanical and chemical stability.</li></ul><h5>Recommended application areas</h5><ul><li>Wide range of different applications, i.e. SEC (size exclusion chromatography) but also for normal phase HPLC and HILIC; good choice for analytical and preparative purposes to separate polar compounds.</li></ul><blockquote>Tip: Normal phase (NP) stationary phases have been the first phases for chromatography and that is why their properties of polarity were determined as ’’normal’’. The stationary phase of a NP column has polar properties and is commonly used with nonpolar solvents as hexane or heptane. The other way round a reversed phase (RP) column has covalent charcteristics and is used with more polar eluents, like mixtures of acetonitrile and water.</blockquote>Stationary phase Eurospher II 100 Si is provided in these column types: analytical, semi-preparative and preparative.Eurospher II 100 Si Analytical Columns are available with these parameters:<ul><li>Column length (mm): 50, 100, 150, 250</li><li>Column ID (mm): 3, 4, 4.6</li><li>Particle size (µm): 3, 5</li></ul>Eurospher II 100 Si Semi-Preparative Standard Columns are available with these parameters:<ul><li>Column length (mm): 30, 50, 125, 150, 250</li><li>Column ID (mm): 8, 16</li><li>Particle size (µm): 5, 10</li></ul><h3>KNAUER (U)HPLC Columns</h3>Widest range of HPLC and UHPLC columns for all separation modes and applications.<ul><li>Safe Investment: Robust and reliable columns for attractive price&nbsp;</li><li>Separation Mode: Reversed Phase, HILIC, Normale</li><li>Simplicity: Easy purchase via our online store with fast delivery</li><li>Application: All-rounder for research or highly specialised for high-throughput analysis? We have the best column for your requirements.</li><li>Flexibility: Wide selection of column and particle sizes, for (U)HPLC applications up to 1000 bar</li></ul>KNAUER offers the perfect column for any small molecule separation. No matter which separation mode, molecule and the mobile phase, we offer a suitable (U)HPLC stationary phase. Choose from a wide range of modifications, particle sizes and column dimensions to suit your application. To elongate the lifetime of your column, you can choose to use a suitable precolumn.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp" alt="KNAUER: KNAUER (U)HPLC Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_KNAUER_U_HPLC_C8_and_C8_A_Columns_083c60f401.webp 182w," sizes="100vw" width="787" height="674">

KNAUER Eurospher II Chiral AM Columns for NP & RP (USP L51)

Eurospher II Chiral AM uses the chiral selector Amylose-tris-(3,5 dimethylphenylcarbamate) and is equivalent to Chiralpak AD. 

Eurospher II Chiral AM uses the chiral selector Amylose-tris-(3,5 dimethylphenylcarbamate) and is equivalent to Chiralpak AD. KNAUER offers 2 different CPS versions: Eurospher II Chiral AM is designed for separations in normal phase (NP) mode and Eurospher II Chiral AM-R &nbsp;for separations in reversed phase (RP) mode.<h5>Properties</h5><ul><li>Silica gel: ultra pure, &gt; 99.99 %</li><li>Metal content: &lt; 10 ppm</li><li>Particle size: 3 μm, 5 μm, 10 μm</li><li>Particle form: spherical</li><li>Pore size of base material: 1000 Å</li><li>Chiral selector: Amylose-tris-(3,5-dimethylphenylcarbamate) for Chiral AM&nbsp;</li></ul><h5>Key features</h5><ul><li>KNAUER offers these chiral stationary phases for two different separation modes: Eurospher II Chiral AM is designed for separations in normal phase (NP) mode, Eurospher II Chiral AM-R for separations in reversed phase mode.</li></ul><h5>Recommended application areas</h5><ul><li>Eurospher II Chiral AM columns are able to separate neutral, acidic and basic racemates.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Chiral_AM_906d13b0b5.webp" alt="KNAUER: Eurospher II Chiral AM" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Chiral_AM_906d13b0b5.webp 245w," sizes="100vw" width="690" height="388"><blockquote>Stationary phase Eurospher II Chiral AM (AM-R) is provided in these column types: analytical, semi-preparative and preparative.</blockquote>Eurospher II Chiral AM and AM-R Analytical Columns are available with these parameters:<ul><li>Column length (mm): 50, 100, 150, 250</li><li>Column ID (mm): 4, 4.6</li><li>Particle size (µm): 3, 5, 10</li></ul>Eurospher II Chiral AM and AM-R Semi-Preparative Standard Columns are available with these parameters:<ul><li>Column length (mm): 150, 250</li><li>Column ID (mm): 10</li><li>Particle size (µm): 5, 10</li></ul><h3>KNAUER Chiral HPLC Columns</h3>For analytical, preparative and SMB chiral separations<ul><li>Column Brand<ul><li>Eurospher II</li></ul></li><li>Reversed Phase Modifications<ul><li>Chiral NR-R</li><li>Chiral AM-R</li><li>Chiral OM-R</li></ul></li><li>Normal Phase Modifications<ul><li>Chiral NR</li><li>Chiral AM</li><li>Chiral OM</li></ul></li><li>Flexibility: Wide selection of column and particle sizes, for preparative and analytical applications</li><li>Expandable: Upscaling even for continuous SMB</li><li>Application Service: We offer a customized screening service for your analytes. You will receive an optimal column recommendation including the method parameters.</li></ul><h4>Eurospher II Chiral</h4>Based on ultra-high purity silica, the Eurospher II chiral column materials are characterized by high enantioselectivity and loadability.&nbsp;Available in a wide range of dimensions for analytical, preparative and SMB (simulated moving bed) applications, Eurospher II Chiral columns are the perfect choice for even the most challenging enantioseparation tasks&nbsp;Since chiral separations are not very well predictable, KNAUER offers a chiral screening service for your samples (Article number: AL0220).<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Eurospher_II_chiral_48c53afebe.jpg" alt="KNAUER: Eurospher II chiral" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Eurospher_II_chiral_48c53afebe.jpg 245w," sizes="100vw" width="1369" height="633"><blockquote>Tip: Some of the most popular eluents for HPLC (such as acetone, chloroform, DMF, DMSO, MEK, toluene, dioxane, ethyl acetate, methylene chloride, pyridine and THF) which may be remaining in your HPLC system, can destroy Eurospher II Chiral AM and OM phases even in small concentrations! It is highly recommended that the HPLC system is flushed with appropriate eluents before the installation of the chiral column.</blockquote>

KNAUER Eurospher II Chiral OM Columns for NP & RP (USP L40, USP L93)

Eurospher II Chiral OM uses the chiral selector Cellulose-tris-(3,5-dimethylphenylcarbamate) and is equivalent to Chiralcel OD. 

Eurospher II Chiral OM uses the chiral selector Cellulose-tris-(3,5-dimethylphenylcarbamate) and is equivalent to Chiralcel OD. KNAUER offers 2 different CPS versions: Eurospher II Chiral OM is designed for separations in normal phase (NP) mode and Eurospher II Chiral OM-R for separations in reversed phase (RP) mode.<h5>Properties</h5><ul><li>Silica gel: ultra pure, &gt; 99.99 %</li><li>Metal content: &lt; 10 ppm</li><li>Particle size: 3 μm, 5 μm, 10 μm</li><li>Particle form: spherical</li><li>Pore size of base material: 1000 Å</li><li>Chiral selector: Cellulose-tris-(3,5-dimethyl- phenylcarbamate) for Chiral OM</li></ul><h5>Key features</h5><ul><li>KNAUER offers these chiral stationary phases for two different separation modes: Eurospher II Chiral OM is designed for separations in normal phase (NP) mode, Eurospher II Chiral OM-R for separations in reversed phase mode.</li></ul><h5>Recommended application areas</h5><ul><li>Eurospher II Chiral OM columns are able to separate neutral, acidic and basic racemates.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Chiral_OM_c2a3f1a159.webp" alt="KNAUER: Eurospher II Chiral OM" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Chiral_OM_c2a3f1a159.webp 245w," sizes="100vw" width="690" height="388"><blockquote>Stationary phase Eurospher II Chiral OM (OM-R) is provided in these column types: analytical, semi-preparative and preparative.</blockquote>Eurospher II Chiral OM and OM-R Analytical Columns are available with these parameters:<ul><li>Column length (mm): 50, 100, 150, 250</li><li>Column ID (mm): 4, 4.6</li><li>Particle size (µm): 3, 5, 10</li></ul>Eurospher II Chiral OM and OM-R Semi-Preparative Standard Columns are available with these parameters:<ul><li>Column length (mm): 150, 250</li><li>Column ID (mm): 10</li><li>Particle size (µm): 5, 10</li></ul><h3>KNAUER Chiral HPLC Columns</h3>For analytical, preparative and SMB chiral separations<ul><li>Column Brand<ul><li>Eurospher II</li></ul></li><li>Reversed Phase Modifications<ul><li>Chiral NR-R</li><li>Chiral AM-R</li><li>Chiral OM-R</li></ul></li><li>Normal Phase Modifications<ul><li>Chiral NR</li><li>Chiral AM</li><li>Chiral OM</li></ul></li><li>Flexibility: Wide selection of column and particle sizes, for preparative and analytical applications</li><li>Expandable: Upscaling even for continuous SMB</li><li>Application Service: We offer a customized screening service for your analytes. You will receive an optimal column recommendation including the method parameters.</li></ul><h4>Eurospher II Chiral</h4>Based on ultra-high purity silica, the Eurospher II chiral column materials are characterized by high enantioselectivity and loadability.&nbsp;Available in a wide range of dimensions for analytical, preparative and SMB (simulated moving bed) applications, Eurospher II Chiral columns are the perfect choice for even the most challenging enantioseparation tasks&nbsp;Since chiral separations are not very well predictable, KNAUER offers a chiral screening service for your samples (Article number: AL0220).<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Eurospher_II_chiral_48c53afebe.jpg" alt="KNAUER: Eurospher II chiral" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Eurospher_II_chiral_48c53afebe.jpg 245w," sizes="100vw" width="1369" height="633"><blockquote>Tip: Some of the most popular eluents for HPLC (such as acetone, chloroform, DMF, DMSO, MEK, toluene, dioxane, ethyl acetate, methylene chloride, pyridine and THF) which may be remaining in your HPLC system, can destroy Eurospher II Chiral AM and OM phases even in small concentrations! It is highly recommended that the HPLC system is flushed with appropriate eluents before the installation of the chiral column.</blockquote>

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