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.

Phenomenex

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.

KNAUER

Phenomenex Strata NH2 Solid Phase Extraction (SPE)

This amino phase offers strong polar selectivity and hydrogen bonding under normal phase conditions or can be used as a weak anion-exchange sorbent.

Normal Phase Solid Phase Extraction (SPE)This amino phase offers strong polar selectivity and hydrogen bonding under normal phase conditions or can be used as a weak anion-exchange sorbent.<figure class="image"><img style="aspect-ratio:500/150;" src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_nh2_a7c3599f55.webp" alt="Phenomenex: Strata-NH2" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_nh2_a7c3599f55.webp 245w," sizes="100vw" width="500" height="150"></figure><ul><li>Surface Area (m²/g): -</li><li>Separation Mode: Normal Phase</li><li>Pore Size: 100</li><li>Particle Size: 25, 55</li><li>Recommended Use: Strong polar selectivity and hydrogen bonding under normal phase conditions or can be used as a weak anion-exchange sorbent</li></ul><h4>Starting Method</h4><h5>Strata NH2 – Weak Anion-Exchange</h5><ul><li>Condition: 1 mL Methanol</li><li>Equilibrate: 1 mL Water, pH 6-7</li><li>Load: Pretreated sample, pH 6-7</li><li>Wash 1: 1 mL 25mM Ammonium Acetate Buffer, pH 6-7</li><li>Wash 2: 1 mL Methanol, dry under vacuum for 2-5 min</li><li>Elute Any Acid: 1 mL 5% NH4OH in Methanol</li><li>Elute Weak Acids: 1 mL 5% Formic Acid in Methanol</li></ul>Based on 100 mg/1 mL sorbent mass. The above is a convenient starting point for SPE method development, further optimization may be required to tailor the method for your specific extraction needs.

Phenomenex Strata SAX Solid Phase Extraction (SPE)

The quaternary amine group on this sorbent remains positively charged under all conditions, giving a strong anion-exchange mechanism of retention.

Ion-Exchange Solid Phase Extraction Sorbent (SPE)The quaternary amine group on this sorbent remains positively charged under all conditions, giving a strong anion-exchange mechanism of retention.<figure class="image"><img style="aspect-ratio:500/150;" src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_sax_470d923b27.webp" alt="Phenomenex: Strata-SAX" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_sax_470d923b27.webp 245w," sizes="100vw" width="500" height="150"></figure><ul><li>Surface Area (m²/g): -</li><li>Separation Mode: Ion Exchange</li><li>Particle Size: 55</li><li>Recommended Use: Extraction of weakly acidic compounds</li></ul><h4>Starting Method</h4><h5>Strata SAX – Strong Anion-Exchange</h5><ul><li>Condition: 1 mL Methanol</li><li>Equilibrate: 1 mL DI Water</li><li>Load: Pretreated sample, pH 6-7</li><li>Wash 1: 1 mL 25mM Ammonium Acetate Buffer, pH 6-7</li><li>Wash 2: 1 mL Methanol, dry under vacuum for 2-5 min</li><li>Elute: 1 mL 5% Formic Acid in Methanol</li></ul>Based on 100 mg/1 mL sorbent mass. The above is a convenient starting point for SPE method development, further optimization may be required to tailor the method for your specific extraction needs.

Phenomenex Strata Screen-A Solid Phase Extraction (SPE)

Incorporates the hydrophobic selectivity of a C8 phase and strong anion-exchange for the extraction of acidic drugs from biological matrices.

Mixed-Mode Solid Phase Extraction (SPE) SorbentIncorporates the hydrophobic selectivity of a C8 phase and strong anion-exchange for the extraction of acidic drugs from biological matrices.<figure class="image"><img style="aspect-ratio:500/150;" src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_Screen_A_f370bdfd48.webp" alt="Phenomenex: Strata Screen-A" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_Screen_A_f370bdfd48.webp 245w," sizes="100vw" width="500" height="150"></figure><ul><li>Surface Area (m²/g): -</li><li>Separation Mode: Multi-Mode</li><li>Particle Size: 55</li><li>Recommended Use: Extracts acidic drugs from biological matrices</li></ul><h4>Starting Method</h4><h5>Strata Screen-A Strong Anion-Exchange</h5><ul><li>Condition: 1 mL Methanol</li><li>Equilibrate: 1 mL Water</li><li>Load: Pretreated sample</li><li>Wash 1: 1 mL 25mM Ammonium Acetate Buffer, pH 6-7</li><li>Wash 2: 1 mL Methanol, dry under vacuum for 2-5 min</li><li>Elute: 1 mL 5% Formic Acid in Methanol</li></ul>Based on 100 mg/1 mL sorbent mass. The above is a convenient starting point for SPE method development, further optimization may be required to tailor the method for your specific extraction needs.

Phenomenex Strata Screen-C Solid Phase Extraction (SPE)

Incorporates the hydrophobic selectivity of a C8 phase and strong cation exchange for the extraction of basic drugs from biological matrices.

Strong Cation-Exchange Solid Phase Extraction (SPE)Incorporates the hydrophobic selectivity of a C8 phase and strong cation exchange for the extraction of basic drugs from biological matrices.<figure class="image"><img style="aspect-ratio:500/150;" src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_Screen_C_b60bb2b7e4.webp" alt="Phenomenex: Strata Screen-C" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_Screen_C_b60bb2b7e4.webp 245w," sizes="100vw" width="500" height="150"></figure><ul><li>Surface Area (m²/g): 500, m²/g, 500 m²/g</li><li>Separation Mode: Multi-Mode</li><li>Pore Size: 70</li><li>Particle Size: 55</li><li>Recommended Use: Extraction of basic drugs from biological matrixes</li></ul><h4>Starting Method</h4><h5>Strata Screen-C Strong Cation-Exchange</h5><ul><li>Condition: 1 mL Methanol</li><li>Equilibrate: 1 mL Acidified Water</li><li>Load: Pretreated sample (acidified)</li><li>Wash 1: 1 mL 0.1N HCl in Water</li><li>Wash 2: 1 mL 0.1N HCl in Methanol, dry under vacuum for 2-5 min</li><li>Elute: 1 mL 5 % NH4OH in Methanol</li></ul>Based on 100 mg/1 mL sorbent mass. The above is a convenient starting point for SPE method development, further optimization may be required to tailor the method for your specific extraction needs.

Phenomenex Strata Screen-C GF Solid Phase Extraction (SPE)

Optimized for gravity flow, this sorbent offers hydrophobic selectivity from a C8 phase and strong cation-exchange properties for the extraction of basic drugs.

Strong Cation-Exchange Solid Phase Extraction (SPE)Optimized for gravity flow, this sorbent offers hydrophobic selectivity from a C8 phase and strong cation-exchange properties for the extraction of basic drugs from biological matrixes. Offers the selectivity of Screen-C in a gravity flow particle size for viscous samples.<h4>Starting Method</h4><h5>Strata Screen-C GF Strong Cation-Exchange</h5><ul><li>Condition: 1 mL Methanol</li><li>Equilibrate: 1 mL Acidified Water</li><li>Load: Pretreated sample (acidified)</li><li>Wash 1: 1 mL 0.1N HCl in Water</li><li>Wash 2: 1 mL 0.1N HCl in Methanol, dry under vacuum for 2-5 min</li><li>Elute: 1 mL 5 % NH4OH in Methanol</li></ul>Based on 100 mg/1 mL sorbent mass. The above is a convenient starting point for SPE method development, further optimization may be required to tailor the method for your specific extraction needs.

KNAUER Eurospher II 100 C8 & C8A (U)HPLC Columns (USP L7)

C8 is a silica gel based stationary phase in reversed phase mode with alternative selectivity compared to C18 phases. 

Classical and hydrophilic/aqueous C8 columns for HPLC and UHPLC (USP L7)C8 is a silica gel based stationary phase in reversed phase mode with alternative selectivity compared to C18 phases. Compared to C18 phases, these columns show less retention due to the lower hydrophobicity.<ul><li>Ultra pure, spherical high performance HPLC phase based on silica gel</li><li>Monomeric C8 (Octyl) modification, standard endcapping, with 10 % carbon content (~ 50 % endcapping)</li></ul><h5>Properties</h5><ul><li>Separation mechanism: Hydrophobic interaction(lower compared to C18 phases)</li></ul><h5>Key features</h5><ul><li>Classical C8 phase, standard 50 % endcapping and 10 % 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>Similar selectivity to C18 phase but less retention due to the lower hydrophobicity; useful for determination of:<ul><li>Water soluble vitamins</li><li>Steroids</li><li>Catecholamines</li><li>Sedatives</li></ul></li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_C8_rp_non_endcapped_3f7727d3fd.webp" alt="KNAUER: C8 RP Non-endcapped" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_C8_rp_non_endcapped_3f7727d3fd.webp 148w," sizes="100vw" width="304" height="321">Hydrophilic C8A phase offers an alternative, more polar selectivity. It is suited for highly polar reversed phase applications with up to 100 % aqueous mobile phases.&nbsp;<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_C8_A_e1f371165e.webp" alt="KNAUER: C8A" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_C8_A_e1f371165e.webp 198w," sizes="100vw" width="473" height="373"><blockquote>Tip: Caution! Even for short term storage all buffer solutions have to be rinsed from the column to prevent crystallization effects.</blockquote>Stationary phases Eurospher II 100 C8 and C8A are provided in these column types: analytical, semi-preparative and preparative.Eurospher II 100 C8 and C8A 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 C8 and C8A 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.<figure class="image"><img style="aspect-ratio:787/674;" 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"></figure>

KNAUER Eurospher II 100 C18 (U)HPLC Columns (USP L1)

Stationary phase Eurospher II 100 C18 (U)HPLC is the most often used stationary phase in reversed phase mode

Classical Reversed Phase columns for HPLC and UHPLC (USP L1)Most often used stationary phase in reversed phase mode. Silica gel based columns with C18 modification are available with or without endcapping. Classically endcapped phases are slightly more hydrophobic and unpolar than the not endcapped phases.<h5>Properties</h5><ul><li>Separation mechanism: Hydrophobic interaction</li><li>Ultra pure, spherical high performance HPLC phase based on silica gel</li><li>Unpolar, monomeric C18 (Octadecyl) modification, endcapped, with 16 % carbon content (~ 50 % endcapping).</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 C18 phase with ca. 50 % endcapping and resulting 16 % carbon content, outstanding mechanical and chemical stability.</li></ul><h5>Recommended application areas</h5><ul><li>acidic, basic and neutral analytes in reversed phase mode, for example sulphonamides</li><li>anabolic steroids</li><li>anti-psychotics</li><li>beta blocker</li><li>sudan dyes</li><li>phenols and preservatives</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_C18_non_endcapped_6e4fce9989.webp" alt="KNAUER: C18 Non-endcapped" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_C18_non_endcapped_6e4fce9989.webp 245w," sizes="100vw" width="682" height="420"><blockquote>Tip: Caution! Never use classical C18 phases with 100 % aqueous mobile phase. The hydrophobic C18 chains will collapse</blockquote>Stationary phase Eurospher II 100 C18 is provided in these column types: analytical, semi-preparative and preparative.Eurospher II 100 C18 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 C18 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 C18A (U)HPLC Columns (USP L1)

C18A phases can be operated under 100 % aqueous conditions without destroying the stationary phase, what is not recommended for classical C18 phases

C18A 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 hydrophilic endcapping. Because of their modification, C18A 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.<h5>Properties</h5><ul><li>Separation mechanism: Hydrophobic and polar interaction</li><li>Ultra pure, spherical high performance HPLC phase based on silica gel</li><li>Polar, monomeric C18 (Octadecyl) modification, polar endcapping, with 10 % carbon content (~ 50 % endcapping).</li></ul><h5>Key features</h5><ul><li>C18 A phase with alternative, more polar selectivity, suited for the use with pure aqueous mobile phases, 50 % endcapping and resulting 10 % carbon content, 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>Polar endcapped C18 phase for water soluble and polar analytes, 100 % aqueous eluents for analysis of very polar compounds:<ul><li>basic pharmaceutical ingredients</li><li>water soluble vitamins</li><li>catecholamines</li><li>as well as organic acids.</li></ul></li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_C18_A_6f4b0c3063.webp" alt="KNAUER: C18A" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_C18_A_6f4b0c3063.webp 245w," sizes="100vw" width="690" height="428"><blockquote>Tip: With an endcapping the influence of nonderivatized silanol groups can be minimized. The endcapping reagent is generally a smaller silane than used for derivatisation. This treatment reduces the unwanted interaction of polar or charged analytes (acids, bases ect.) because the amount of available silanol groups is reduced.</blockquote>Stationary phase Eurospher II 100 C18A is provided in these column types: analytical, semi-preparative and preparative.Eurospher II 100 C18A 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 C18A 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.<figure class="image"><img style="aspect-ratio:787/674;" 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"></figure>

KNAUER Eurospher II 100 C18H (U)HPLC Columns (USP L1)

C18H stationary phase with a special, high efficiency or polymeric unpolar endcapping style. Suited for the use of mobile phase in an extended pH range from typically pH 1–12. 

Hydrophobic / pH stable C18H Columns for more unpolar analytes in Reversed Phase (USP L1)C18H stationary phase with a special, high efficiency or polymeric unpolar endcapping style. Because of the high carbon content and the protection of the Silica gel these materials are also suited for the use of mobile phase in an extended pH range from typically pH 1–12.While a high endcapped C18H phase is characterized mostly by the high carbon content. A polymeric endcapped phase also provides an increased steric selectivity.<h5>Properties</h5><ul><li>Separation mechanism: Hydrophobic interaction</li><li>Ultra pure, spherical high performance HPLC phase based on silica gel</li><li>Nonpolar, monomeric C18 (Octadecyl) modification, high efficiency endcapping with 17 % carbon content (~ 99 % endcapping)</li></ul><h5>Key features</h5><ul><li>Nonpolar C18 phase with high efficiency endcapping and 17 % carbon content, resulting in higher pH stability in the range of 1–12, 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>Recommended alternative to Kromasil 100 C18, for acidic, basic and neutral analytes in reversed phase mode with extended pH range.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_C18_H_c5531f7d87.webp" alt="KNAUER: C18H" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_C18_H_c5531f7d87.webp 226w," sizes="100vw" width="687" height="475"><blockquote>Tip: All analytical KNAUER columns can be used in reversed flow direction for example for cleaning. Please refer to our Column care and use documents on the website for further information about storage conditions and cleaning procedures.</blockquote>Stationary phase Eurospher II 100 C18H is provided in these column types: analytical, semi-preparative and preparative.Eurospher II 100 C18H 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 C18H 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 style="aspect-ratio:787/674;" 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 C18P (U)HPLC Columns (USP L1)

KNAUER´s most unpolar C18P phase with excellent shape selectivity. It features polymeric, high efficiency endcapping of 99 % and 20 % carbon content, exceptional pH stability in the range of 1–12.

C18P columns with trifunctional modifications (USP L1): Hydrophobic and stearic interactionsKNAUER´s most unpolar C18P phase with excellent shape selectivity. It features polymeric, high efficiency endcapping of 99 % and 20 % carbon content, exceptional pH stability in the range of 1–12, and outstanding mechanical and chemical stability.<h5>Properties</h5><ul><li>Separation mechanism: Hydrophobic and stearic interaction</li><li>Ultra pure, spherical high performance HPLC phase based on silica gel</li><li>Unpolar, trifunctional C18 (Octadecyl) modification, high efficiency endcapping, with 20 % carbon content (~ 99 % endcapping)&nbsp;</li></ul><h5>Key features</h5><ul><li>KNAUER´s most unpolar C18 phase, polymeric, high efficiency endcapping of 99 % and 20 % carbon content, higher pH stability in the range of 1-12, 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 to standard C18; stationary phase in Eurospher II C18 family with the highest carbon load; fully endcapped; excellent shape selectivity and pH stability.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_C18_P_f093126fa9.webp" alt="KNAUER: C18P" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_C18_P_f093126fa9.webp 245w," sizes="100vw" width="278" height="174"><blockquote>Tip: Not all C18 phases are comparable! When replacing an existing column, always have a close look at the characteristics like carbon load, pore size and specific surface area.</blockquote>Stationary phase Eurospher II 100 C18P is provided in these column types: analytical, semi-preparative and preparative.Eurospher II 100 C18P 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 C18P 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.<figure class="image"><img style="aspect-ratio:787/674;" 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"></figure>

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