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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Phenomenex Strata Phenyl Solid Phase Extraction (SPE)

A short alkyl chain with a phenyl group provides moderate hydrophobic selectivity and aromatic selectivity through π−π interactions.

Retention of Aromatic CompoundsA short alkyl chain with a phenyl group provides moderate hydrophobic selectivity and aromatic selectivity through π−π interactions.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_Phenyl_5bc4ec65e4.webp" alt="Phenomenex: Strata Phenyl" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_Phenyl_5bc4ec65e4.webp 245w," sizes="100vw" width="500" height="150"><ul><li>Surface Area (m²/g): 500</li><li>Separation Mode: Reversed Phase</li><li>Pore size: 70</li><li>Particle Size: 55</li><li>Recommended Use: Extraction of aromatic and hydrophobic compounds</li></ul><h4>Starting Method</h4><h5>Strata Reversed Phase</h5><ul><li>Condition: 1 mL Methanol</li><li>Equilibrate: 1 mL DI Water</li><li>Load: Pretreated sample</li><li>Wash: 1 mL 5% Methanol in DI Water, dry under vacuum for 2-5 min</li><li>Elute: 1 mL 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 SDB-L Solid Phase Extraction (SPE)

A rugged polymer sorbent that is pH stable from 1-14 and offers hydrophobic and aromatic selectivity for reversed phase applications.

Styrene-Divinylbenzene Solid Phase Extraction (SPE) SorbentA rugged polymer sorbent that is pH stable from 1-14 and offers hydrophobic and aromatic selectivity for reversed phase applications.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_SDB_L_49e276aab1.jpg" alt="Phenomenex: Strata-SDB-L" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_SDB_L_49e276aab1.jpg 193w," sizes="100vw" width="208" height="168"><ul><li>Surface Area (m²/g): 500</li><li>Separation Mode: Reversed Phase</li><li>Pore size: 260</li><li>Particle Size: 100</li><li>Recommended Use: Extraction of hydrophobic and aromatic compounds</li></ul><h4>Starting Method</h4><h5>Strata Reversed Phase</h5><ul><li>Condition: 1 mL Methanol</li><li>Equilibrate: 1 mL DI Water</li><li>Load: Pretreated sample</li><li>Wash: 1 mL 5% Methanol in DI Water, dry under vacuum for 2-5 min</li><li>Elute: 1 mL 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 Eco Screen Solid Phase Extraction (SPE)

This proprietary normal phase sorbent is topped with sodium sulfate to remove any excess water and is used for the extraction of hydrocarbons from environmental samples.

Specialty Solid Phase Extraction (SPE) SorbentThis proprietary normal phase sorbent is topped with sodium sulfate to remove any excess water and is used for the extraction of hydrocarbons from environmental samples, resulting in high recoveries of naphthalene.

Phenomenex Strata EPH Solid Phase Extraction (SPE)

This specialty normal phase sorbent was developed for the fractionation of aliphatic and aromatic hydrocarbons from environmental samples.

Specialty Solid Phase Extraction (SPE) SorbentThis specialty normal phase sorbent was developed for the fractionation of aliphatic and aromatic hydrocarbons from environmental samples.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_eph_6f99720a51.webp" alt="Phenomenex: Strata-EPH" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_eph_6f99720a51.webp 245w," sizes="100vw" width="500" height="150"><ul><li>Surface Area (m²/g): -</li><li>Separation Mode: Multi-mode</li><li>Particle Size: 200</li><li>Recommended Use: Fractionation of aliphatic and aromatic hydrocarbons from environmental samples</li></ul><h4>Starting Method</h4><h5>Strata EPH Normal Phase</h5><ul><li>Condition: IPA/DCM</li><li>Equilibrate: Hexane</li><li>Load: Pretreated sample</li><li>Wash: 5 % DCM in Hexane</li><li>Elute: 1:1 Hexane / DCM or 1:1 Hexane / IPA</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 PAH Solid Phase Extraction (SPE)

Strata PAH is a proprietary sorbent designed to provide high recoveries of polycyclic aromatic hydrocarbons from water.

Specialty Solid Phase Extraction (SPE) SorbentStrata PAH (Polycyclic Aromatic Hydrocarbons) is a proprietary sorbent designed to provide high recoveries of polycyclic aromatic hydrocarbons from water (as specified in EPA Method 550.1) while simultaneously removing humic acids from the extract.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_pah_c48e1fab83.webp" alt="Phenomenex: Strata-PAH" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_pah_c48e1fab83.webp 245w," sizes="100vw" width="500" height="150"><ul><li>Surface Area (m²/g): -</li><li>Separation Mode: Reversed Phase</li><li>Particle Size: 55</li><li>Recommended Use: Extraction of polycyclic aromatic hydrocarbons from water (as specified in EPA Method 550.1) while simultaneously removing humic acids from the extract</li></ul>

Phenomenex Strata PFAS Solid Phase Extraction (SPE)

A new stacked cartridge able to offer 2x gains in productivity and reduce the need for multiple tubes, transfer steps, and wasted time. 

Specialty Solid Phase Extraction (SPE) SorbentA new stacked cartridge able to offer 2x gains in productivity and reduce the need for multiple tubes, transfer steps, and wasted time. This product is recommended to be used for EPA 1633 and DOD QSM 5.1/5.3 guidelines to minimize multiple sample but still provide high recoveries of low level PFAS (Per- and Polyfluoroalkyl Substances) in solid samples, soils, biota, sediments, or non-drinking water samples.<ul><li>Surface Area (m²/g): -</li><li>Separation Mode: Multi-Mode</li><li>Pore Size: 0</li><li>Recommended Use: for EPA 1633 and DOD QSM 5.1/5.3 applications for diverse matrices and non-drinking water PFAS applications</li></ul><h4>Stacked SPE Cartridges for Efficient PFAS Extraction</h4>Strata PFAS is a stacked solid phase extraction cartridge for EPA method 1633 and DOD QSM 5.1/5.3 applications.<ul><li>Reliable SPE with 2x gains in productivity</li><li>Reproducible extraction</li><li>Reduced need for multiple tubes, transfer steps, and wasted time</li></ul>

Phenomenex Strata CN Solid Phase Extraction (SPE)

Strata CN is a polar phase with slight hydrophobic selectivity in reversed phase mode and moderate polar selectivity in normal phase mode.

Normal Phase Solid Phase Extraction (SPE)A polar phase with slight hydrophobic selectivity in reversed phase mode and moderate polar selectivity in normal phase mode.<figure class="image"><img style="aspect-ratio:500/150;" src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_cn_769c96c476.webp" alt="Phenomenex: Strata-CN" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_cn_769c96c476.webp 245w," sizes="100vw" width="500" height="150"></figure><ul><li>Surface Area (m²/g): -</li><li>Separation Mode: Normal Phase</li><li>Particle Size: 55</li><li>Recommended Use: Extraction of polar compounds such as those that contain hydroxyl groups.</li></ul><h4>Starting Method</h4><ul><li>Condition: IPA/DCM</li><li>Equilibrate: Hexane</li><li>Load: Pretreated sample</li><li>Wash: 5 % DCM in Hexane</li><li>Elute: 1:1 Hexane / DCM or 1:1 Hexane / IPA</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 Silica (Si-1) Solid Phase Extraction (SPE)

Strata Silica (Si-1) is a normal phase SPE sorbent with unbonded silica particle that offers strong polar selectivity.

Normal Phase Solid Phase Extraction (SPE)A polar phase with slight hydrophobic selectivity in reversed phase mode and moderate polar selectivity in normal phase mode.<figure class="image"><img style="aspect-ratio:500/150;" src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_si_e4eb885006.webp" alt="Phenomenex: Strata-Silica (Si-1)" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_si_e4eb885006.webp 245w," sizes="100vw" width="500" height="150"></figure><ul><li>Surface Area (m²/g): 550, m²/g, null m²/g, 490 m²/g</li><li>Separation Mode: Normal Phase</li><li>Pore Size: 70</li><li>Particle Size: 55</li><li>Recommended Use: Extraction of polar compounds that are similar in structure</li></ul><h4>Starting Method</h4><h5>Strata Normal Phase Method</h5><ul><li>Condition: IPA/DCM</li><li>Equilibrate: Hexane</li><li>Load: Pretreated sample</li><li>Wash: 5 % DCM in Hexane</li><li>Elute: 1:1 Hexane / DCM or 1:1 Hexane / IPA</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 Melamine Solid Phase Extraction (SPE)

A proprietary phase that allows for the simultaneous extraction of melamine and cyanuric acid out of food and biological samples.

Specialty Solid Phase Extraction (SPE) SorbentA proprietary phase that allows for the simultaneous extraction of melamine and cyanuric acid out of food and biological samples.

Phenomenex Strata SCX Solid Phase Extraction (SPE)

A benzene sulfonic acid group is bonded to the surface of the silica particle, giving strong cation-exchange selectivity.

Ion-Exchange Solid Phase Extraction (SPE) SorbentA benzene sulfonic acid group is bonded to the surface of the silica particle, giving strong cation-exchange selectivity.<ul><li>Extraction of 1 °, 2 °, and 3 amines</li></ul><figure class="image"><img style="aspect-ratio:791/384;" src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_SCX_SPE_f35df1035c.jpg" alt="Phenomenex: Strata SCX" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_SCX_SPE_f35df1035c.jpg 245w," sizes="100vw" width="791" height="384"></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 basic compounds</li></ul><h4>Starting Method</h4><h5>Strata SCX – 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.

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Oligos Made Easy - Part 3: IP-RP

News from LabRulezLCMS Library - Week 08, 2026

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