Meeting EU Drinking Water Standards: The Critical Role of Sample Prep in Trace Contaminant Analysis

<h3>Charged for Action: The Hidden Secrets of AEX Oligonucleotide Analysis</h3>Oligonucleotides—short, well-defined fragments of DNA or RNA—have become indispensable tools in modern life sciences. They underpin cutting-edge applications in molecular diagnostics, gene therapy, and pharmaceutical development. Before oligonucleotides can be confidently used in research or clinical settings, however, their quality must be rigorously assessed. Purity, sequence integrity, length distribution, and chemical modifications all play a decisive role in their performance.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Oligos_Made_Easy_Part_2_AEX_2_45eee54fa0.jpg" alt="KNAUER: Oligos Made Easy - Part 2: AEX" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Oligos_Made_Easy_Part_2_AEX_2_45eee54fa0.jpg 245w," sizes="100vw" width="1534" height="711">Among the analytical techniques available today, anion exchange chromatography (AEX) stands out as a robust and highly informative method for characterizing oligonucleotides. By exploiting their intrinsic negative charge, AEX provides detailed insight into product composition and impurity profiles that are difficult to obtain by other approaches.<blockquote><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/article/6808">Part 1 of the Oligos series: A Practical Guide to Oligonucleotide Production – From Concept to Final Product</a></blockquote><h4>How Scientists Read Oligonucleotides Using Charge</h4>At the core of AEX lies a simple but powerful principle: oligonucleotides carry a negatively charged phosphate backbone. This charge increases in a predictable way with strand length and, to a lesser extent, sequence composition. Anion exchange chromatography uses this property to separate oligonucleotides based on differences in charge strength and interaction with a positively charged stationary phase.As a result, AEX has become one of the most widely used analytical tools for evaluating oligonucleotide quality. It allows scientists to distinguish full-length products from truncated species, degradation products, or closely related variants—often with single-nucleotide resolution.<h4>Why Ion Exchange Works: Binding, Retention, and Release</h4>Ion exchange chromatography (IEX) relies on electrostatic interactions between analytes and a charged stationary phase. In the case of oligonucleotides, anion exchange is used, where negatively charged molecules interact with positively charged functional groups on the resin—most commonly quaternary amines.The system consists of two main components:<ul><li>Stationary phase: A positively charged resin that binds anionic analytes.</li><li>Mobile phase: An aqueous buffer system, typically combined with a salt gradient, that controls both pH and elution strength.</li></ul>Retention in AEX is governed primarily by charge. Molecules with weaker overall charge interact less strongly with the stationary phase and elute earlier, while more highly charged oligonucleotides bind more tightly and require stronger elution conditions.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Oligos_Made_Easy_Part_2_AEX_Figure_1_IEX_overview_including_elution_order_dependency_on_analyte_charge_3419ad3075.jpg" alt="KNAUER: Oligos Made Easy - Part 2 AEX: Figure 1 IEX overview including elution order dependency on analyte charge." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Oligos_Made_Easy_Part_2_AEX_Figure_1_IEX_overview_including_elution_order_dependency_on_analyte_charge_3419ad3075.jpg 245w," sizes="100vw" width="1583" height="654"><h4>The Five-Step Workflow of Ion Exchange Chromatography</h4>AEX separations generally follow a well-established sequence of steps:<ol><li>Column equilibration The column is conditioned with the starting buffer until the baseline and pH are stable. This ensures that all charged sites on the resin are ready for interaction.</li><li>Sample loading Samples, prepared in the starting buffer, are introduced under conditions that promote binding of the target oligonucleotides while minimizing retention of unwanted impurities.</li><li>Washing The column is washed with the starting buffer to remove uncharged or weakly interacting components. The baseline stabilizes as these species are flushed away.</li><li>Elution Bound oligonucleotides are released using a salt or pH gradient. Increasing ionic strength introduces competing ions that displace the analytes from the resin. Weakly bound species elute first; strongly charged oligonucleotides elute later.</li><li>Regeneration and re-equilibration A high-salt buffer removes any remaining bound material. The column is then returned to starting conditions in preparation for the next analysis.</li></ol><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Oligos_Made_Easy_Part_2_AEX_Figure_2_Five_steps_of_IEX_procedure_in_blue_outlined_using_an_example_chromatogram_in_red_38dd70b1b1.jpg" alt="KNAUER: Oligos Made Easy - Part 2 AEX: Figure 2 Five steps of IEX procedure (in blue), outlined using an example chromatogram (in red)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Oligos_Made_Easy_Part_2_AEX_Figure_2_Five_steps_of_IEX_procedure_in_blue_outlined_using_an_example_chromatogram_in_red_38dd70b1b1.jpg 245w," sizes="100vw" width="1583" height="674"><h4>Why AEX Is Especially Effective for Oligonucleotides</h4>The repeating phosphate backbone of oligonucleotides gives rise to a strong and uniform anionic character across a wide pH range (typically pH 7–9). This makes oligonucleotides exceptionally well suited for anion exchange separations.Key factors influencing AEX behavior include:<ul><li>Charge density: Longer oligonucleotides carry more negative charges and therefore exhibit stronger retention.</li><li>Resin chemistry: Strong and weak anion exchangers differ in functional groups and pH stability, influencing selectivity and robustness.</li><li>Buffer composition: The choice of buffering ions and salt gradients directly affects elution strength and resolution.</li></ul>Salt gradients—commonly based on chloride ions—compete with the oligonucleotide backbone for binding sites on the resin. By carefully tuning gradient slope and composition, analysts can achieve highly reproducible and finely resolved separations.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Oligos_Made_Easy_Part_2_AEX_Figure_3_Ionic_interactions_and_p_H_influence_on_Anion_Exchange_Chromatography_AEX_612e231ba4.jpg" alt="KNAUER: Oligos Made Easy - Part 2 AEX: Figure 3 Ionic interactions and pH influence on Anion Exchange Chromatography (AEX)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Oligos_Made_Easy_Part_2_AEX_Figure_3_Ionic_interactions_and_p_H_influence_on_Anion_Exchange_Chromatography_AEX_612e231ba4.jpg 245w," sizes="100vw" width="1547" height="593"><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Oligos_Made_Easy_Part_2_AEX_Figure_4_AEX_buffer_selection_and_gradient_strategy_chromatogram_with_red_buffer_gradient_curve_53fd1bb11b.jpg" alt="KNAUER: Oligos Made Easy - Part 2 AEX: Figure 4 AEX buffer selection and gradient strategy (chromatogram with red buffer gradient curve)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Oligos_Made_Easy_Part_2_AEX_Figure_4_AEX_buffer_selection_and_gradient_strategy_chromatogram_with_red_buffer_gradient_curve_53fd1bb11b.jpg 245w," sizes="100vw" width="1600" height="327"><h4>AEX as the Gold Standard for Oligonucleotide Separation</h4>Anion exchange chromatography has become the method of choice for both analytical and preparative oligonucleotide workflows. Its advantages include:<ul><li>High resolving power: Closely related impurities, including n–1 or n–2 species, can often be separated and quantified.</li><li>Predictable retention behavior: In many cases, retention time correlates linearly with oligonucleotide length, simplifying identification.</li><li>Compatibility with modified oligonucleotides: Even chemically modified sequences retain their anionic nature, allowing AEX to resolve both products and related impurities.</li><li>Excellent control via gradient elution: Salt gradients provide precise tuning of selectivity and resolution.</li></ul>Typically, shorter or degraded oligonucleotides elute at lower ionic strength, while full-length products with higher charge density appear later in the chromatogram.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Oligos_Made_Easy_Part_2_AEX_Figure_5_AEX_Advantages_and_Challenges_7835521e34.jpg" alt="KNAUER: Oligos Made Easy - Part 2 AEX: Figure 5 AEX Advantages and Challenges." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Oligos_Made_Easy_Part_2_AEX_Figure_5_AEX_Advantages_and_Challenges_7835521e34.jpg 245w," sizes="100vw" width="1535" height="707"><h4>Final Perspective: Mastering AEX with Confidence</h4>Anion exchange chromatography may appear complex at first, but with thoughtful optimization of pH, buffer composition, and gradient conditions, it becomes a highly precise and reliable tool for oligonucleotide analysis. When properly applied, AEX delivers sharp peaks, excellent resolution, and robust performance—even for challenging sequences and modifications.For laboratories developing or refining oligonucleotide workflows, AEX offers both analytical depth and operational confidence.<blockquote>If you would like to discuss AEX method development or optimization for oligonucleotides, feel free to contact us at sales@knauer.net. More insights into practical oligonucleotide analysis will follow in our “Oligos Made Easy” series.For technical questions or in-depth discussion, the author can be reached at kindler@knauer.net</blockquote>

Oligos Made Easy - Part 2: AEX

Although modern agriculture needs to be based on accurate real-time data on soil, plant, and environmental conditions, affordable, sufficiently sensitive, and robust monitoring devices for this purpose are currently missing. According to scientists, low-cost sensors based on new smart materials and printing technologies offer a suitable solution. The results of multidisciplinary research thus far and proposals for the development of these devices have been presented by researchers from Czechia, Great Britain, Spain, and the USA in a review article in the prestigious journal <a target="_blank" rel="noopener noreferrer" href="https://www.nature.com/articles/s41467-026-68778-6#Abs1">Nature Communications</a>.“Sensor technologies for monitoring plant health are still in their infancy. Only simple sensors capable of monitoring basic parameters such as pH, soil moisture, or temperature are commonly available on the market. However, if farmers are to face current challenges, including climate change, and ensure sufficient food for humanity, they need much more effective tools that will enable them to monitor, for example, various pathogens, including bacteria and fungi. In our opinion, a suitable solution is a combination of new smart materials and printing for the production of inexpensive, durable, and scalable materials,” said the article’s first author, David Panáček from CATRIN, who worked on the study during his internship at Imperial College London.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/CATRIN_Soucasne_senzory_nestaci_Vedci_navrhuji_novou_cestu_ke_sledovani_zdravi_rostlin_b4014952a3.jpg" alt="CATRIN: David Panáček" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_CATRIN_Soucasne_senzory_nestaci_Vedci_navrhuji_novou_cestu_ke_sledovani_zdravi_rostlin_b4014952a3.jpg 208w," sizes="100vw" width="1536" height="1152">Sensors for monitoring plant health, for example, lag behind similar devices used in human medicine. According to the authors, advances in materials science, which will enable the development of scalable sensor technologies, play a key role in this potential shift. “Printing techniques, including inkjet printing, screen printing, aerosol printing, 3D printing, and direct laser writing, offer flexible ways to produce flexible sensors, large-area sensors, and sensors integrated directly into plants. The review article summarizes recent advances in printable low-dimensional materials for agricultural sensors, analyzes their physico-chemical properties in relation to sensor performance, and discusses key challenges and future opportunities requiring interdisciplinary integration,” said one of the corresponding authors, Michal Otyepka.The research brought together materials scientists, chemists, biologists, sensing experts, and printing technology specialists. Materials research and the use of graphene-based smart materials were led by scientists from CATRIN at Palacký University and VŠB-Technical University of Ostrava. Plant biologists from CATRIN contributed their knowledge of plant development, their responses to stress conditions, and the monitoring of their properties. Researchers from Imperial College London took care of the electronics, while representatives from<a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/companies/36"> CEITEC – VUT</a> focused on printing technologies. The team also included leading experts in sensing from the Catalan Institute of Nanoscience and Nanotechnology in Barcelona, and Joseph Wang of the University of California San Diego, the “father of sensing and electrochemistry,” also contributed his extensive knowledge.“This is a groundbreaking study on this topic, which has managed to attract some truly big names in their respective fields. Last but not least, the study demonstrates that interdisciplinarity at CATRIN gives rise to completely new and promising research topics, such as plant sensing and its use for studying plant-environment interactions and smart agriculture,” added another corresponding author, Nuria De Diego.

Current sensors are not good enough. Scientists propose a new way to monitor plant health

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The Czech Advanced Technology and Research Institute (CATRIN) at Palacký University is a cutting-edge scientific hub dedicated to advancing research in the fields of nanotechnology, biotechnology, and biomedicine. At its core, CATRIN boasts outstanding scientific teams, featuring international researchers. We emphasize interdisciplinarity, foster global collaborations, and work to translate our research findings into practical applications.

CATRIN

Organomation, founded in 1959, designs and manufactures high-quality nitrogen evaporators and extraction systems. Known for innovation and durability, their lab instruments are used globally for efficient sample preparation with strong customer support.

Organomation

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 Kinetex Core-Shell Polar C18 LC Columns

The Kinetex® 2.6 µm Polar C18 is a core-shell based particle with a polar modified surface and a C18 alkyl phase.

The Kinetex® 2.6 µm Polar C18 is a core-shell based particle with a polar modified surface and a C18 alkyl phase. This versatile column can easily upgrade existing fully porous 5 µm and 3 µm methods to shorten run time, increase sensitivity, and even provide greater resolution with much higher efficiency levels. Combined with being 100 % aqueous stable, the Kinetex Polar C18 is a unique column that combines performance and selectivity.<ul><li>Compatible with All Analytical HPLC/UHPLC Systems</li><li>L:1 C18 with Unique Polar Retention</li><li>Compatible with 100 % Aqueous Mobile Phases</li><li>USP: L1</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Kinetex_polar_C18_60ab4fb700.webp" alt="Phenomenex: Kinetex-polar-C18" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Kinetex_polar_C18_60ab4fb700.webp 245w," sizes="100vw" width="500" height="150"><ul><li>Carbon Load: 9 (effective), 9 (effective) %</li><li>Particle Size (μm): 2.6, 3</li><li>Recommended Use: Combined C18 and polar modified surface that provides polar and non-polar retention alongside 100% aqueous stability</li></ul><h4>C18 and Polar Selectivity</h4>Combined C18 and polar modified surface that provides polar and non-polar retention alongside 100 % aqueous stability.<h4>Increase Polar Retention and Hydrophobic Selectivity</h4>Increase polar selectivity without sacrificing hydrophobic selectivity with the Kinetex Polar C18. The Kinetex Polar C18 is an excellent all-purpose, 100% aqueous stable phase for use with multi-compound mixes that contain polar and non-polar compounds, or even single class methods that have closely related compounds, impurities, or metabolites.<h4>Kinetex Where Performance Meets the Right Selectivity</h4>Quickly improve the productivity and performance of your existing methods and utilize the core-shell advantage to deliver performance you need at backpressures the system can handle. Select from a variety of column selectivity to find the right phase for the application.<h3>Kinetex Core-Shell Technology Columns</h3>Kinetex Core-Shell Technology delivers dramatic improvements in efficiency over conventional fully porous media, which can be leveraged to increase resolution, significantly improve productivity, reduce solvent consumption, and decrease costs. Whether you are running high-performance liquid chromatography (HPLC) or ultra-high performance liquid chromatography (UHPLC) methods, the Kinetex core-shell family can deliver shockingly improved performance over the current column you are using. Phenomenex designs, manufactures, and sells its very own silica and organo-silica core-shell particles.Advantages of Kinetex HPLC Columns<ul><li>Performance gains on ANY liquid chromatography system</li><li>System-to-system and lab-to-lab method portability</li><li>Improve the productivity of older, established methods.</li></ul><h4>How Does Core-Shell Technology Work?</h4>Core-shell technology in chromatography is a revolutionary approach that enhances the efficiency of HPLC systems while minimizing costs. Core-shell particles are designed with a solid, non-porous silica core surrounded by a porous outer layer. This unique structure allows for faster analyte mass transfer between the mobile and stationary phases, as diffusion occurs only through the thin, porous shell rather than the entire particle. This minimizes band broadening, leading to higher separation efficiency and sharper peaks.The consistency in size and shape of core-shell particles further enhances separation efficiency by reducing variability in analyte movement. As a result, core-shell HPLC columns provide high efficiency and resolution at lower backpressures, making them an ideal choice for labs looking to improve their existing HPLC systems without the need for costly UHPLC equipment.Core-shell technology thus offers a cost-effective alternative to upgrading to UHPLC systems, enabling labs to maximize the efficiency of their current HPLC setups. The formation of these particles through advanced sol-gel processing techniques ensures uniformity and reliability, making them a valuable tool in modern chromatography. By using the Kinetex HPLC column, laboratories can achieve faster analysis times and higher productivity while maintaining excellent separation performance.<h3>Kinetex Core-Shell Performance on Any LC System</h3>The 5 versatile particle sizes allow you to select the best fit for your instrument.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_HPLC_and_UHPLC_Kinetex_Core_Shell_Technology_Columns_5_particle_sizes_bbed75c36f.jpg" alt="Phenomenex: Five versatile particle sizes of Kinetex Core-Shell Technology Columns" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_HPLC_and_UHPLC_Kinetex_Core_Shell_Technology_Columns_5_particle_sizes_bbed75c36f.jpg 245w," sizes="100vw" width="1341" height="333"><h3>Particle Chemistry</h3>Using sol-gel processing techniques that incorporate nano-structuring technology, a durable, homogeneous porous shell is grown on a solid silica core to create a Kinetex Core-Shell particle. This particle morphology results in less band broadening for all four sources of UHPLC band broadening compared to fully porous particles and thus delivers extremely high efficiencies.<ul><li>Optimized for Ultra-High Performance</li><li>Superior Core-Shell Quality</li><li>Core-Shell Scalability and Portability</li></ul>Kinetex particles are characterized by an exceptionally consistent size distribution, with particles being nearly monodispersed, meaning they are uniform in size. This precise uniformity plays a crucial role in minimizing variability within the column, leading to enhanced separation efficiency and sharper peaks.The nearly monodispersed nature of these particles ensures that the flow of the mobile phase remains consistent, reducing the likelihood of irregularities that can impact results. As a result, Kinetex columns deliver highly reliable and reproducible performance, making them ideal for achieving consistent analytical outcomes acrLC Kinetex Core-Shell Technolooss various applications.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_HPLC_and_UHPLC_Kinetex_Core_Shell_Technology_Columns_Kinetex_Polar_C18_vs_Fully_Porous_phase_a2729b64e5.jpg" alt="Phenomenex: Kinetex Polar C18 vs Fully Porous phase" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_HPLC_and_UHPLC_Kinetex_Core_Shell_Technology_Columns_Kinetex_Polar_C18_vs_Fully_Porous_phase_a2729b64e5.jpg 245w," sizes="100vw" width="1376" height="581"><h3>Core-shell vs Fully Porous</h3><h4>High-Efficiency‚ High-Density Particle</h4>The combination of a consistent, solid, high-density core along with proprietary column packing technologies in the Kinetex HPLC column ensures optimum bed structure and high column performance. This carefully designed core structure promotes uniform packing of the particles, which is essential for minimizing band-broadening effects that can arise from Eddy Diffusion.The manufacturing process of Kinetex columns is tightly controlled, focusing on factors such as particle size distribution, surface and bonding homogeneity, and packing quality. This meticulous engineering leads to uniform packing and minimized band-broadening, resulting in superior separation efficiency.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Core_shell_vs_Fully_Porous_60601b6fa3.jpg" alt="Phenomenex: Core-shell vs Fully Porous." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Core_shell_vs_Fully_Porous_60601b6fa3.jpg 245w," sizes="100vw" width="904" height="506"><h3>Expand Your Core-Shell Selectivity Toolbox</h3>Kinetex core-shell particle LC columns deliver exceptional performance enhancements across any LC system, offering unmatched efficiency and resolution. With a choice of 11 diverse stationary phases, these columns cater to a wide range of chromatographic applications, ensuring optimal separation for various analytes.Additionally, the availability of five versatile particle sizes allows for precise method tailoring, enabling both high-speed and high-resolution separations. Whether you're using HPLC or UHPLC systems, Kinetex columns provide the flexibility and performance needed to achieve superior analytical results.<h3>Top 5 Pros of Kinetex Core-Shell Technology</h3><ul><li>Productivity: Kinetex Core-Shell Technology significantly enhances method productivity with minimal effort. By simply replacing traditional, fully porous columns with Kinetex HPLC columns, users can achieve better resolution, sensitivity, and overall productivity without extensive method redevelopment. This easy switch allows for immediate improvements in chromatographic performance, making it a cost-effective upgrade to existing methods.</li><li>Portability The Kinetex Core-Shell columns are available in a range of particle sizes (1.3 µm to 5 µm), which ensures method portability across different HPLC and UHPLC systems. This scalability allows for consistent retention and selectivity across various particle sizes while accommodating different backpressure levels, making it easier to transfer methods between instruments.</li><li>Performance Kinetex Core-Shell Technology delivers superior chromatographic efficiency compared to fully porous particles. This efficiency boost enables chromatographers to maximize the performance of their HPLC/UHPLC systems, ensuring optimal results with higher resolution and sharper peaks, even under similar method conditions.</li><li>Phases With 11 unique phase selectivities available, Kinetex Core-Shell Technology offers unmatched versatility for method development. This wide selection of phase chemistries allows for tailored separations and simplified optimization, ensuring the best possible results for a wide range of applications.</li><li>Pressure Kinetex Core-Shell columns provide higher efficiency at lower system backpressures compared to fully porous columns. This allows users to achieve superior chromatographic performance on conventional LC instruments without the need for ultra-high-pressure systems, making it a practical choice for routine analyses.</li></ul>

Products from category C18 HPLC columns distributed by Phenomenex - page 3

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Current sensors are not good enough. Scientists propose a new way to monitor plant health

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Oligos Made Easy - Part 2: AEX