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

SIELC Samplify Automated sampling system

Samplify Is a device which allows unattended sampling of a reaction mixture or bioprocess or continue in line flow by taking small amount of liquid from the monitoring mixture and collecting it in a vial or a 96 wells plate

Samplify™ Is a device which allows unattended sampling of a reaction mixture or bioprocess or continue in line flow by taking small amount of liquid from the monitoring mixture and collecting it in a vial or a 96 wells plate. It also allows to dilute the sample with assigned dilution ratio and can provide reaction quenching to preserve the sample state at time of sampling. It has two main components: an autosampler and a probe. The Samplify™ &nbsp;controlled and setup by a PC software.<h3>Description</h3>It is a common task in the lab to periodically sample a reactor or a fermenter to obtain information about reaction kinetic, completion and have a tangible representation of intermediate states of a dynamic process. This usually done manually with pipettes or syringes, using stopwatch to measure time and requires to be in the lab during the entire process.With Samplify it can be done in automated mode. When an automated sampling process is used it increases accuracy, safety, and productivity. It reduces potential samples cross contamination, and exposure of the reaction mixture to oxygen or moisture, when anaerobic or moisture free conditions are required.<ul><li>Based on a proprietary alpha/beta mechanical configuration, Alltesta Miniature Autosampler and patent pending sample probe offers affordable and reliable automation for many analytical and liquid-handling applications.&nbsp;</li><li>Small controllable volume of sample can be programmed and precisely removed from the enclosed or open system. The sample will then be transferred to a vial with inert solvent with measured volume to create a controllable dilution factor.</li><li>A quench solution can be automatically preloaded in each vial to provide termination of reaction or biological process, and preserve sample content in the time of probing.</li><li>In order to effectively mix samples with diluents or quenching reagents a shaking capability of the autosampler tray can be initiated after each sample cycle.</li><li>PC based software allows quick, but flexible, setup of the sampling experiment. Several preloaded methods can be quickly adapted to a particular needs of the user.</li><li>For temperature sensitive samples the entire autosampler can be placed in the temperature controlled environment.</li><li>The device small size allow to place it close to the reactor and use short connection lines to minimize dispersion. Also a small cooler can be used to keep samples in cold conditions after they are collected.</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/SIELC_SIELC_Samplify_Automated_sampling_system_937b70e8d2.jpg" alt="SIELC: SIELC Samplify™ Automated sampling system." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_SIELC_SIELC_Samplify_Automated_sampling_system_937b70e8d2.jpg 245w," sizes="100vw" width="1346" height="663"><h3>Specifications</h3><h4>Samplify™ Autosampler:</h4><ul><li>Syringe volume: 4.0 mL</li><li>Pressure: up to 250 psi</li><li>Valve configuration: 7×6</li><li>Power Requirements: 24 VDC</li><li>Current Requirements: Up to 1.0 A</li><li>Dimensions (WHL): 160 x 145 x 195 mm / 6.3 x 5.71 x 7.68 in</li><li>Weight: &nbsp;3 kg / 6.6 lb</li><li>Inlets/Outlets: Thread 10-32 UNF compression type</li><li>Materials in contact with liquid: SS316, PTFE, PEEK</li><li>Tray capacity: 48 vials 1.8 mL volume or 96 wells plate</li><li>Communication: USB virtual serial port</li></ul><h4>Samplify™ Probe:</h4><ul><li>Connection: requires Alltesta-Samplify autosampler</li><li>Dimensions: 1 x 1 inch, DIA ¼ inch. Immersion length up to 6 inch</li><li>Materials in contact with liquid: Stainless Steel 316 (316L), PEEK &amp; PTFE</li><li>Variable sample volume: from 5 to 500 µL</li><li>Max. working pressure: 120 psi (8 bar)</li><li>Max. working temperature: &nbsp;200 °C</li></ul><h3>Software</h3>The Samplify can be controlled:<ul><li>directly through your software via serial commands (Alltesta™ protocol available upon request, please contact us at support@sielc.com),</li><li>remotely through our cloud software (autosampler.cloud),</li><li>directly via our Samplify PC software, allowing to fully control all the parameters of the sampling operations</li></ul><h3>Available Custom Options</h3>Metal-free version of the syringe pump includes no metal contact pump head.

PBI Barocycler 2320EXT Sample Preparation System

The Barocycler 2320EXT is a compact, bench top instrument that can process up to 16 samples simultaneously using PCT MicroTubes.

<h4>For the PCT-HD Sample Preparation System</h4>Pressure Cycling Technology (PCT) is a unique, patented technology platform based on repeated cycles of hydrostatic pressure between ambient (14.7 psi) and ultra-high levels. These rapid changes in pressure are used to control biomolecular interactions for applications such as accelerated proteolytic digestion, and improved extraction of cellular components, including proteins and lipids. The PCT platform allows for a high degree of safety, speed, reproducibility, and convenience in modern sample preparation protocols.The PCT-HD Sample Preparation System is a proven PCT-based workflow for processing small tissue samples for proteomic and other applications. PCT-HD combines efficient, hands-off tissue homogenization and protein extraction with pressure-enhanced digestion, for rapid, efficient and reproducible generation of peptides for MS analysis. This unique workflow combines two of PBI’s innovative sample preparation tools: the Barocycler 2320EXT and our patentpending PCT MicroPestles. PCT-HD and the Barocycler 2320EXT can provide unprecedented speed and reproducibility for biomarker discovery, yielding peptides ready for clean-up and MS within 2-4 hours from the start of tissue processing.The Barocycler 2320EXT is a compact, bench top instrument that can process up to 16 samples simultaneously using PCT MicroTubes. Features that come standard with the 2320EXT include: data input and output options to accommodate validation and quality control; computer-operated control with touch screen programming and automatic data logging; and the ability to control multiple pressure cycling parameters, such as the rate of pressure increase/decrease, both the high and low pressure levels, and the shape of the pressure profile (e.g., sine wave, square wave, and others). In addition, the 2320EXT is available with a choice of two different methods for temperature control (an external circulating waterbath for heating and cooling, or a built-in electric heater).<blockquote>Patent Pending</blockquote><h4>The Barocycler 2320EXT</h4><ul><li>Computer-operated control with Touch Screen Interface</li><li>Pressure Range: ambient - 45,000psi (310 MPa)</li><li>Choice of temperature control - heating/cooling or heating only</li><li>Max Temperature: 95˚C</li><li>Min Temperature: 4˚C with circulating waterbath, ambient with electric heating</li><li>Insulated closure for easier use at high temperatures</li><li>Chamber capacity: up to 16 samples in MicroTubes</li><li>Easily accessible USB port on front panel</li><li>Requires 110psi input air pressure</li><li>Input air pressure can be provided by an air compressor, house air or nitrogen lines, air or nitrogen tanks.</li><li>Pressure medium: Distilled Water</li></ul><h4>Touch Screen Interface</h4>Pressure Profiles are programmed via an onboard touch screen, which can be connected to a network. The instrument is also equipped with a USB port that can be used to connect a mouse or keyboard to the 2320EXT.<ul><li>Pressure Mode Settings: Barocycler, Ramp, Waveform</li><li>Cycled or Static Pressure</li><li>Network Enabled</li><li>Automatic Logging of All Run Parameters</li><li>Data Output&nbsp;</li><li>Save and Record Programs</li><li>Real-time pressure display graph shows pressure and temperature throughout the run</li><li>Touch Screen Temperature Control (with electric heating option only)</li></ul><h4>MicroTubes and MicroPestles</h4>The 2320EXT comes with a full MicroTube Adapter Kit, that includes the MicroTube Cartridges, Capper Tool, and other accessories that are required when using PCT MicroTubes in the 2320EXT. PCT μPestles, used in conjunction with PCT MicroTubes in the Barocycler, are designed for rapid, hands-off homogenization and extraction when working with minute amounts of solid tissue. PCT MicroTubes and MicroPestles are an integral part of the PCT-HD workflow.<ul><li>Process up to 3mg of solid tissue in 30uL of extraction reagent</li><li>Process as few as 5 x 104 cells</li><li>MicroTubes are constructed of non-wetting, low binding FEP plastic</li><li>MicroPestles are made from inert PTFE (Teflon)</li></ul>

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