<p><strong>An international research team, which included scientists from the Faculty of Science at Palacký University and the Institute of Physics of the Czech Academy of Sciences, has succeeded in unraveling the complex mechanism by which a chemical bond is formed during a collision between molecules. The experts found that the reaction only takes place if the molecules are oriented towards each other within a very narrow range of angles – within the so-called cone of reaction. This joint research has thus provided an answer to one of the fundamental questions of chemistry: under what conditions do chemical bonds form between molecules. The results of the study&nbsp;</strong><i><strong>Spatially resolving the cone of reaction for a single molecule</strong></i><strong>&nbsp;were published in the prestigious scientific journal&nbsp;Science.</strong></p><p>Many chemical reactions begin with the collision of two particles. However, for a new chemical bond to form, it is not enough for the molecules simply to come into contact. Their collision must occur with sufficient energy, in the correct relative orientation and at the right location. Under normal conditions, such as in solutions or gases, molecules collide chaotically, and the precise parameters of these collisions cannot therefore be controlled.</p><h4><strong>Molecules under control</strong></h4><p>Scientists were able to control the collisions of individual molecules on a copper surface and monitored the process using a <strong>scanning tunnelling microscope</strong>. They used the instrument not only to visualise individual molecules, but also to deliberately accelerate the reactants towards one another. They subsequently analysed each collision with atomic-level resolution. This enabled them to determine unequivocally whether a new chemical bond had formed between the molecules.</p><h5><i><strong>“What is hidden in the statistics of billions of collisions in conventional chemistry, we have managed to break down into individual cases and map directly.” Adam Matěj</strong></i></h5><p>A key finding of the study is that the outcome of a collision is determined by the extremely precise orientation of the molecules. A new bond was formed only when the target molecule was oriented within a few degrees of the direction of movement of the other molecule. When rotated by more than fifteen degrees, the molecules simply bounced off each other without any reaction.</p><h4><strong>The precise orientation of the molecules is crucial</strong></h4><p><i>“For the first time, we were able to observe, using a single molecule, exactly how precisely it must be oriented for the reaction to take place at all. What is hidden in the statistics of billions of collisions in conventional chemistry, we have managed to break down into individual cases and map directly,” </i>said Adam Matěj from the Department of Physical Chemistry at the Faculty of Science.</p><p>The theoretical part of the study, in which researchers from<strong> Palacký University </strong>and <strong>the Institute of Physics of the Czech Academy of Sciences</strong> were involved, played a significant role. Using quantum-mechanical calculations, they explained why the ‘reaction cone’ is so narrow. It turned out that the reactive carbon atom is surrounded by hydrogen atoms, which block the access of the reacting molecule from almost all directions.</p><h4><strong>The arrangement of atoms restricts access to the reaction</strong></h4><p>The calculations also shed light on a surprising experimental result. The chemical reaction took place even when the molecule moved along an adjacent row of copper atoms, where, according to the original assumptions, no bond should have formed.</p><h5><i><strong>“The strength of this work lies in the fact that the experiment and theory have been brought together into a single picture. The microscope showed what happens during the collision, and the calculations explained why.” Pavel Jelínek</strong></i></h5><p><i>“The explanation lies in the slight displacement of a single copper atom on the surface. The target’s bond to the surface pulls it out of its position and brings it close enough to the neighbouring row that it can literally take over the projectile and direct it to the correct spot. This shows that the surface is not merely a passive substrate, but actively participates in the reaction itself and can even facilitate pathways that would otherwise be unfavourable,” </i>noted Adam Matěj.</p><h4><strong>The surface also determines the course of the reaction</strong></h4><p>The results are significant for the development of so-called surface reactions, in which new materials and nanostructures are purposefully assembled from individual molecules. A better understanding of the influence of the spatial arrangement of molecules will enable the design of molecular building blocks so that they bond more reliably and efficiently. This represents an important step towards the development of technologies based on the controlled construction of structures atom by atom.</p><p><i>“The strength of this work lies in the fact that experiment and theory have been brought together into a single picture. The microscope showed what happens during the collision, and the calculations explained why. Without a theoretical model, we would have found it difficult to discover that the movement of a single surface atom is behind the unexpected course of the reaction,” </i>added Pavel Jelínek from the Institute of Physics of the Czech Academy of Sciences.</p><blockquote><p>The study&nbsp;<i>Spatially resolving the cone of reaction for a single molecule</i>&nbsp;was produced in collaboration between researchers from the University of Graz, the Institute of Physics of the Czech Academy of Sciences, Palacký University in Olomouc, Charles University and Humboldt University in Berlin.</p></blockquote>

Scientists reveal when chemical bonds form in molecular collisions 

<p><strong>In our </strong><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/article/7741"><strong>previous article, we introduced the main types of detectors used in HPLC</strong></a><strong>. This time, we take a closer look at the performance characteristics of LC detectors and the specifications that should be considered when assessing whether a detector is suitable for a particular chromatographic separation. We will also compare the most common detector technologies and provide some practical guidance for choosing the right option for a specific application.</strong></p><h3><strong>What Defines an Ideal HPLC Detector?</strong></h3><p>With such a wide variety of HPLC detectors available, an obvious question arises: why is there no single detector that works for every application? The simple answer is that no detector can satisfy every analytical requirement at the same time. Nevertheless, most detector designs aim to achieve a similar set of desirable properties.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Figure_1_Detector_requirements_334605c913.webp" alt="KNAUER: Figure 1 - Detector requirements" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Figure_1_Detector_requirements_334605c913.webp 245w," sizes="100vw" width="1024" height="384"></p><h4><strong>1. High Sensitivity – Detecting Very Small Amounts</strong></h4><p>An ideal detector should be capable of measuring very low quantities of analyte, often in the nanogram or even picogram range. High sensitivity leads to lower limits of detection (LOD), can reduce sample preparation requirements, and is particularly valuable for applications such as impurity analysis or pharmacokinetic studies.</p><p>Some detector technologies, including fluorescence detection (FLD), electrochemical detection (ECD), and mass spectrometry (MS), can achieve extremely high sensitivity. However, this level of performance is often limited to specific classes of compounds.</p><h4><strong>2. Good Selectivity or Broad Applicability – Knowing What Is Being Detected</strong></h4><p>Selectivity describes how effectively a detector responds to the target analyte while minimizing interference from the sample matrix or mobile phase.</p><p>Depending on the analytical task, a detector may need to be highly selective, responding only to compounds with specific characteristics such as fluorescence or electrochemical activity. In other cases, broader applicability may be more important, allowing a wide range of compounds to be detected regardless of their molecular structure.</p><h4><strong>3. Linear Response and Broad Dynamic Range – Reliable Quantification</strong></h4><p>A good detector should provide a linear response across a sufficiently wide concentration range. This makes it possible to accurately quantify both major components and trace impurities within the same analytical method.</p><p>A broad linear range simplifies calibration and improves confidence in quantitative results. Detector response should also remain highly reproducible from one injection to another.</p><h4><strong>4. Compatibility with HPLC Conditions – Fitting the Chromatographic Method</strong></h4><p>An ideal detector should be compatible with both gradient and isocratic elution, commonly used mobile phases and additives, typical flow rates, and standard HPLC operating temperatures.</p><p>Poor compatibility may restrict method flexibility or force compromises in chromatographic performance. Some detectors provide excellent analytical performance but only under specific operating conditions, making them less suitable for certain methods.</p><h4><strong>5. Stability and Low Noise – Distinguishing Signal from Background</strong></h4><p>A stable baseline with minimal noise and drift improves the signal-to-noise ratio and overall data quality. This becomes especially important in long chromatographic runs, gradient methods, and trace-level analysis.</p><p>Lower baseline noise makes weak analyte signals easier to distinguish and directly contributes to improved detection limits.</p><h4><strong>6. Robustness, Ease of Use, and Maintenance – Supporting Routine Laboratory Work</strong></h4><p>For day-to-day use, a detector should be reliable over long sequences, straightforward to operate, and require as little maintenance as possible.</p><p>In routine laboratories, robustness and ease of operation can be just as important as analytical performance. Simple troubleshooting, low maintenance requirements, and limited consumable costs are major advantages, particularly in high-throughput environments.</p><h3><strong>The Reality: No Detector Offers Everything</strong></h3><p>Since no detector fulfils all these requirements perfectly, detector selection is inevitably a compromise between sensitivity, selectivity, universality, robustness, operating flexibility, and cost.</p><p>For this reason, multi-detector configurations are increasingly common in modern HPLC systems. Combinations such as UV + CAD or UV + MS make it possible to benefit from complementary detection principles within a single analytical workflow.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Table_1_Comparison_of_commonly_used_HPLC_detector_classes_d74817b0f0.jpg" alt="KNAUER: Table 1 - Comparison of commonly used HPLC detector classes." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Table_1_Comparison_of_commonly_used_HPLC_detector_classes_d74817b0f0.jpg 113w," sizes="100vw" width="806" height="1115"></p><h3><strong>Critical Performance Parameters of HPLC Detectors</strong></h3><h4><strong>Data Sampling Rate</strong></h4><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Figure_2_Example_for_too_less_and_too_high_data_sampling_rate_741a53edc6.webp" alt="KNAUER: Figure 2 - Example for too less and too high data sampling rate." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Figure_2_Example_for_too_less_and_too_high_data_sampling_rate_741a53edc6.webp 245w," sizes="100vw" width="1024" height="410"></p><p>The data acquisition rate, also known as the sampling rate, is one of the most important detector settings in HPLC. It describes how many data points are recorded per second and directly influences peak representation, peak shape, area precision, and baseline noise.</p><p>The higher the sampling rate, the more data points are collected. The detector processes the measurements collected over a defined time interval and averages them, and these averaged points are then used to construct the chromatogram.</p><p>At a data rate of 5 Hz, for example, five data points are acquired every second. If too few points are collected across a chromatographic peak, the resulting peak can appear jagged, poorly defined, and analytically unreliable, as illustrated on the left side of Figure 2.</p><p>At the other extreme, a setting such as 100 Hz records 100 points each second, which is often unnecessarily high for conventional HPLC. The optimum sampling rate mainly depends on chromatographic peak width.</p><p>For most standard HPLC applications, a data rate of approximately <strong>10 to 20 Hz</strong> is sufficient to generate a smooth and symmetrical Gaussian peak.</p><p>One consequence of using an excessively high acquisition rate is increased baseline noise. Statistically, the noise of the system depends on the number of data points used for averaging and decreases with the square root of the number of averaged measurements.</p><p>Selecting an appropriate sampling rate is therefore a balance between collecting enough points to describe the chromatographic peak accurately and avoiding unnecessary noise.</p><h4><strong>Noise and Drift</strong></h4><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/KNAUER_Figure_3_Baseline_noise_and_drift_685652e641.webp" alt="KNAUER: Figure 3 - Baseline noise and drift" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_KNAUER_Figure_3_Baseline_noise_and_drift_685652e641.webp 245w," sizes="100vw" width="1024" height="400"></p><p>What exactly is baseline noise? In simple terms, it represents the short-term fluctuations of the detector baseline over a defined period and is expressed in the units appropriate for the particular detector.</p><p>Baseline noise is typically determined from the peak-to-peak variation of the detector signal while the mobile phase passes through the system.</p><p>All HPLC detectors exhibit a certain level of noise. Potential sources include:</p><ul><li>electronic noise,</li><li>detector cell noise,</li><li>detector instability,</li><li>temperature fluctuations,</li><li>mobile-phase effects,</li><li>and other environmental or instrumental influences.</li></ul><p>Noise directly affects detector sensitivity because it determines the <strong>signal-to-noise ratio (S/N)</strong>.</p><p>A chromatographic peak is generally considered reliably detectable when its height is at least three times greater than the calculated baseline noise. This relationship is commonly used to define the <strong>limit of detection (LOD)</strong>.</p><p>The <strong>limit of quantification (LOQ)</strong> requires a stronger signal and is typically defined as approximately ten times the baseline noise.</p><p>Another important parameter affecting sensitivity is baseline drift. Drift reflects the gradual change in detector response over time and therefore provides useful information about long-term detector stability.</p><p>It is helpful to distinguish between short-term peak-to-peak noise and longer-term baseline drift over a defined time interval. Drift can be described as the average slope or change of the baseline within a specific period.</p><p>Excessive drift may reduce sensitivity and complicate chromatographic peak integration.</p><p>Short-term baseline instability can be influenced by contamination or deterioration of detector components, while long-term drift is often related to temperature stability, detector equilibration, or changes occurring within the analytical system.</p><h3><strong>How to Select the Right HPLC Detector</strong></h3><p>There is no universally “best” HPLC detector. The correct detector is simply the one that best matches the analytical task.</p><p>When selecting a detector, several practical questions can help narrow the choice.</p><h4><strong>1. Does the analyte absorb UV light or fluoresce?</strong></h4><p>If the answer is yes, optical detectors such as <strong>UV/VIS</strong> or <strong>FLD</strong> are often the simplest and most effective options.</p><p>UV/VIS detection is widely applicable to compounds containing suitable chromophores, while fluorescence detection provides particularly high sensitivity and selectivity for naturally fluorescent or derivatized analytes.</p><h4><strong>2. Does the analyte lack a chromophore?</strong></h4><p>If UV absorption is weak or absent, detectors such as <strong>RID, ELSD, or CAD</strong> may provide a more appropriate solution.</p><p>These detector types are useful for compounds such as sugars, lipids, polymers, and other analytes that are difficult to monitor by conventional UV detection.</p><h4><strong>3. Is structural information required?</strong></h4><p>If structural information is important, <strong>mass spectrometry</strong> is usually the strongest choice.</p><p>MS provides mass-to-charge information and, when tandem mass spectrometry is used, fragmentation data that can support compound identification and structural characterization.</p><h4><strong>4. Is extremely high sensitivity necessary?</strong></h4><p>For applications requiring very low detection limits, <strong>electrochemical detection</strong> or <strong>mass spectrometry</strong> may be the most suitable options.</p><p>The exact choice depends on the chemical properties of the analyte and the required degree of selectivity.</p><h4><strong>5. Are macromolecules such as proteins or polymers being investigated?</strong></h4><p>For characterization of macromolecules, <strong>MALS</strong> and <strong>viscometry</strong> can provide valuable information about molecular weight, molecular size, branching, and aggregation.</p><p>These techniques are especially powerful when combined with size-exclusion chromatography and can provide information that is not based solely on column elution behavior.</p><p>For a more detailed discussion of detector selection, see the KNAUER blog article <i>“The way you look at it – A comprehensive guide for selecting the appropriate HPLC detector.”</i></p><p>Choosing the detection technology based on analyte properties, required sensitivity, chromatographic conditions, and the type of information needed is essential for obtaining reliable and meaningful HPLC results.</p><h3><strong>Final Thoughts</strong></h3><p>Understanding the desired characteristics and key performance parameters of HPLC detectors helps explain why different detector technologies are suited to different applications.</p><p>No single detector can provide maximum sensitivity, selectivity, universality, robustness, flexibility, and low operating cost simultaneously. Recognizing these trade-offs provides a practical framework for selecting the most appropriate detector for a given chromatographic method.</p><p>Parameters such as data sampling rate, baseline noise, drift, dynamic range, and compatibility with chromatographic conditions are just as important as the underlying detection principle itself.</p><p>In the next articles of this series, we will take a closer look at the individual HPLC detection technologies, beginning with the most widely used optical detection method: <strong>UV/VIS detection</strong>.</p>

Seeing is Believing – Detection Made Easy Part 2: Detector Characteristics

<p><strong>Our Library never stops expanding. What are the most recent contributions to LabRulezLCMS Library in the week of 17th August 2026? Check out new documents from the field of liquid phase, especially HPLC and LC/MS techniques!</strong></p><blockquote><p><span style="font-size:20px;">👉 </span><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library"><span style="font-size:20px;"><strong>SEARCH THE LARGEST REPOSITORY OF DOCUMENTS ABOUT LCMS AND RELATED TECHNIQUES</strong></span></a></p></blockquote><blockquote><p><strong>👉 Need info about different analytical techniques?</strong> Peek into <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library"><strong>LabRulezGCMS</strong></a> or <a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/library"><strong>LabRulezICPMS</strong></a> libraries.</p></blockquote><p>This week we bring you posters by <strong>Agilent Technologies / ASMS, Thermo Fisher Scientific / ASMS </strong>and<strong> Shimadzu / ASMS </strong>and application note by<strong> Waters Corporation!</strong></p><h3><strong>1. Agilent Technologies / ASMS: Quantitation of N-Nitroso Duloxetine N-Nitrosamine Drug Substance Related Impurities (NDSRI) in API and Formulation by 6475 LC/TQ</strong></h3><ul><li>Poster</li><li><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/po_drug_impurities_lc_tq_tp_402_asms_2026_en_agilent_b933b9bddf.pdf"><strong>Full PDF for download</strong></a></li></ul><p>Nitrosamine impurities are nitroso derivatives where the nitroso group is attached to an amine. The active pharmaceutical ingredient (API) derived from a class of nitrosamines are known as N-nitrosamine drugsubstance-related impurities (NDSRI). Nitrosamine impurities in APIs and drug products pose safety concerns, even in small quantities, and thus are a major concern for drug makers [1].&nbsp;</p><p>Analytical methods must be sufficiently sensitive to quantify the nitrosamine of interest at levels as low as 10% of the specification limit and, where feasible, down to ≤5% of the specification limit, for the determination of the limit of detection. LC/MS/MS is an inherently selective and highly sensitive analytical technique that is well suited for the identification and quantification of trace-level impurities at extremely low concentrations. Consequently, LC/MS/MS has been widely adopted within the pharmaceutical industry, particularly for nitrosamine analysis [2-3].&nbsp;</p><p>Therefore, manufacturers must develop and qualify a dedicated analytical method that is appropriate for the specific sample matrix and targeted NDSRIs. An LC/MS/MS method based on multiple reaction monitoring (MRM) was developed for the detection and quantification of the N-nitroso duloxetine NDSRI impurity over a concentration range of 0.5 to 40 ppb (absolute standard concentration), using an atmospheric pressure chemical ionization (APCI) source on an Agilent 6475A LC/TQ instrument.</p><h4><strong>Experimental</strong></h4><ul><li><strong>MS:</strong> <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library?mainauthorItems=10&amp;search=6475"><strong>6475 Triple Quadrupole LC/MS System</strong></a></li><li><strong>Column:</strong> <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library?mainauthorItems=10&amp;search=Poroshell+HPH+C18"><strong>Poroshell HPH C18</strong></a> (4.6*150mm, 2.7µm)</li></ul><h4><strong>Conclusions</strong></h4><ul><li>A highly sensitive and robust MRM LC/MS/MS method was developed for the quantitation of N-nitroso duloxetine in duloxetine hydrochloride API and finished formulation using the Agilent 6475A LC/TQ.&nbsp;</li><li>The optimized chromatographic conditions provided effective separation of the analyte from the API, placebo, and formulation matrices, ensuring reliable quantitation.&nbsp;</li><li>The calibration curve was linear over the concentration range of 0.5-40 ng/mL, with 1/x weighting. R and R2 values were observed for both to be greater than 0.99.&nbsp;</li><li>Recovery studies demonstrated efficient sample extraction, with recoveries ranging from 92-99% in API samples and 109-116% in pellet formulations at the LOQ, specification, and 200% specification levels.&nbsp;</li><li>The method also showed excellent reproducibility across all evaluated concentration levels, confirming its suitability for routine analysis.</li></ul><h3><strong>2. Shimadzu / ASMS: Non-Targeted Analysis of Per- and Polyfluoroalkyl Substances in Environmental Extracts by Microflow LC-QToF Coupled with Multi-spray ESI</strong></h3><ul><li>Poster</li><li><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/TP_562_Non_Targeted_Analysis_of_Per_and_Polyfluoroalkyl_Substances_in_Environmental_Extracts_by_Microflow_LC_Q_To_F_Coupled_with_Multi_spray_ESI_c2a7e1d5bf.pdf"><strong>Full PDF for download</strong></a></li></ul><p>Targeted screening methods are well established for monitoring Perand polyfluoroalkyl substances (PFAS) in environmental samples. However, PFAS comprise a large and evolving class of compounds, creating a need to screen existing, emerging, and transformation products across diverse matrices. Non-targeted Analysis (NTA) allows for the confirmation of suspected PFAS in the environment, but the sample characterization is often limited by analytical sensitivity. Microflow (0.5 – 40 µL/min) coupled with a multi-nozzle emitter enhances sensitivity by improving desolvation. When this is coupled to a high mass accuracy and resolution Quadrupole Time-ofFlight Mass Spectrometer (QToF), capable of data-dependent and independent MS/MS, PFAS characterization of unknown analytes is possible. In this study, various environmental extracts were processed and screened using NTA for PFAS compounds.</p><h4><strong>Methods</strong></h4><p>A <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library?mainauthorItems=1&amp;search=Nexera+Mikros"><strong>Shimadzu Nexera Mikros LC</strong> </a>was used to introduce the sample to a Newomics DuoESI source with an M3 emitter on a <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library?mainauthorItems=1&amp;search=9050"><strong>LCMS-9050 QToF MS</strong></a> (Fig. 1). A direct injection on an octadecyl column without delay column was performed. Direct injection was chosen over trapand-elute configuration to minimize selectivity bias caused by the trap column.&nbsp;</p><h4><strong>Conclusion</strong></h4><p>With the increased sensitivity of microflow LC-QToF coupled with multi-spray ESI with DIA acquisition, Insight Explore aided in NTA PFAS analysis. When paired with Insight Discovery and Profiler, a streamlined batch data processing workflow with statistical analysis was shown to effectively handle complex environmental matrices and their analyses.</p><h3><strong>3. Thermo Fisher Scientific / ASMS: Robust and sensitive quantitation of 18 steroids in human serum using Thermo Scientific TSQ Certis Triple Quadrupole mass spectrometer</strong></h3><ul><li>Poster</li><li><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/po_004707_lsms_18_steroids_tsq_certis_clinical_po004707_asms2026_na_en_244c52437b.pdf"><strong>Full PDF for download</strong></a></li></ul><p>Accurate quantification of endogenous steroids in human serum is essential for biomonitoring physiological functions such as hormone regulation, reproduction, and immune response in clinical research laboratories. Liquid chromatography–tandem mass spectrometry (LC–MS/MS) is the gold standard for steroid analysis due to its superior sensitivity, selectivity, and multiplexing capability compared to immunoassays. However, steroid measurements remain challenging because of low endogenous concentrations and complex serum matrices. Here, we describe a robust and sensitive LC–MS/MS method for the simultaneous quantification of 18 steroids in human serum using the Thermo Scientific TSQ Certis triple quadrupole mass spectrometer (Figure 1). The method leverages advanced ion source design and fast acquisition to deliver enhanced sensitivity, stability and throughput suitable for high-volume laboratory workflows.</p><h4><strong>Materials and methods</strong></h4><h5><strong>Liquid chromatograph – mass spectrometry&nbsp;</strong></h5><p>Samples were analyzed on a <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/744"><strong>Thermo Scientific Vanquish Horizon UHPLC system</strong></a> coupled to the <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/2207"><strong>TSQ Certis MS</strong></a><strong> </strong>operated in selected reaction monitoring (SRM) mode. The mobile phase composition, analytical column details, LC gradient, and overlaid extracted ion chromatograms (EICs) are shown in Figure 3.&nbsp;</p><h5><strong>Data analysis&nbsp;</strong></h5><p>Data were acquired and processed using <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/77"><strong>Thermo Scientific TraceFinder software</strong></a> (v 5.2).</p><h4><strong>Conclusions&nbsp;</strong></h4><p>A sensitive and robust LC–MS/MS method was developed for simultaneous quantification of 18 steroids in human serum using the Vanquish Horizon UHPLC and TSQ Certis MS with OptaMax Plus ion source. The method demonstrated excellent linearity, accuracy, and reproducibility across a wide dynamic range. Optimization of MS conditions, particularly vaporizer temperature, significantly improved sensitivity. Overall, the workflow delivers high sensitivity, selectivity, and long-term stability, providing a reliable solution for high-throughput steroid analysis in clinical and research settings.</p><h3><strong>4. Waters Corporation: Alkaline-hydrolysis Method for PFAS in Textiles and Textiles Products by Xevo™ TQ-S micro with ACQUITY™ UPLC™ H-Class Plus System</strong></h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/720009443_en_0ab4914d72.pdf"><strong>Full PDF for download</strong></a></li></ul><div><div><section><div><div><div><div><div><div><h5><strong>Benefits&nbsp;</strong></h5><ul><li>Alkaline hydrolysis method (EN 17681-1:2025) used for preparing textiles, coated textiles and textile products for PFAS analysis allowed the inclusion of side-chain fluorinated polymers&nbsp;</li><li>Extraction method provided significant advantages in handling complex textile matrices by creating clear extracts free from dispersions, settleable solids and particulates&nbsp;</li><li>Protected the high-value LC-MS/MS components from potential damage&nbsp;</li><li>The method improved analytical sensitivity, reproducibility and accuracy, enabled cost-effective and timeefficient PFAS analysis maintained high analytical quality even for challenging high-matrix samples</li></ul><p>Many PFAS are linked to health concerns because of their ability to interfere with the body’s hormone systems, acting as endocrine disruptors also, linked to other toxic effects. Since textiles come into direct and prolonged contact with the skin, there is an increased risk of human exposure—especially for babies and children.4 In addition, PFAS pose significant environmental concerns. These “forever chemicals” do not readily break down and can be released during manufacturing, washing and disposal, allowing them to enter water pathways and persist in the environment. As a result, testing for PFAS has become increasingly important in the textile industry to demonstrate supply chain transparency, build consumer trust and protect brand reputation.</p><p>Synthetic fluorinated chemicals are categorized into two main groups - non-polymeric PFAS and polymeric PFAS, known for their use as water and grease repellent, heat resistant finishes in textiles, upholstery, leather, apparel, carpet and other industrial applications such as packaging, firefighting foams, non-stick cookware, etc. (Figure 1). PFAS are fluorinated substances contain at least one fully fluorinated methyl or methylene carbon atom (without any H/Cl/Br/I atom attached to it), i.e. with a few noted exceptions, any chemical with at least a perfluorinated methyl group or a perfluorinated methylene group.2 PFAS are classified as long chain and short chain based on their perfluorinated carbon chain length. Short chain fluorinated polymers encompasses a diverse range of chemistries, categorized according to their generic chemical and repeating units structures. Few examples are: derivatives of fluorotelomers, perfluoropolyethers with varying carbon chain lengths and acrylates, epoxylates, urethane, silicones of repeated units based structures.3 Polyfluoroalkyl substances such as fluorotelomer alcohols (FTOHs) contain C–H bonds, rendering them more susceptible to degradation. The ethoxylates in fluorotelomers-methacrylate break down to FTOH whereas polymeric fluorinated urethanes, acrylates break down to PFCAs (non-polymeric and polymeric side chain fluorinated polymers). In contrast, perfluoroalkyl substances such as PFOS and PFOA are extremely persistent due to their fully fluorinated carbon chains.&nbsp;</p><p>In alkaline hydrolysis methods, methanolic aqueous sodium hydroxide is used to break down precursor PFAS such as FTOHs, branched side chain PFAS. This process releases terminal perfluorinated carboxylic acids (PFCAs), which can then be measured. However, the efficiency of hydrolysis varies among different PFAS compounds and the presence of interfering substances such as organic matter or other chemicals in the sample matrix can inhibit the cleavage and detection of these analytes.</p><h4><strong>Experimental</strong></h4><ul><li><strong>LC system:</strong> <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/198"><strong>ACQUITY UPLC H-Class Plus System</strong></a> and SMFTN fitted with PFAS kit</li><li><strong>Column(s):</strong> <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/1823"><strong>XBridge™ BEH™ C18 5 µm Column</strong></a>, 4.6 x 100 mm&nbsp;</li><li><strong>MS system: </strong><a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/209"><strong>Xevo TQ-S micro Mass Spectrometer</strong></a></li></ul><h4><strong>Conclusion&nbsp;</strong></h4><p>By strictly following the critical steps of the alkaline hydrolysis method using methanolic aqueous sodium hydroxide (NaOH) both freely extractable PFAS and those previously bound within side-chain fluorinated polymers such as esters linked to fluorotelomer alcohols (n:2 FTOHs, where n = 4, 6, 8, 10, 12), can be effectively extracted. This approach also safeguards the LC-MS/MS instrumentation from blockages, damage, or contamination by preventing polymer accumulation and matrix interferences.&nbsp;</p><p>The analytical method using the ACQUITY UPLC H-Class Plus System and Xevo TQ-S micro LC-MS/MS System was found to be sensitive, reproducible and accurate, enabling cost-effective and time-efficient PFAS analysis in chemically processed textiles, coated textiles and textile products whilst maintaining high analytical quality even for challenging high-matrix samples.</p></div></div></div></div></div></div></section></div></div>

News from LabRulezLCMS Library - Week 34, 2026

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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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Sildenafil/Tadafil blend analysis

Targeted HPLC analysis of sildenafil and tadalafil blends in pills, tablets, and capsules, confirming identity and determining the amount of both compounds.

<p><strong>The Sildenafil/Tadalafil Blend Analysis is a targeted laboratory test designed to confirm the identity and determine the amount of sildenafil and tadalafil in combined oral dosage forms.</strong></p><p>The analysis is suitable for pills, tablets, and capsules containing both compounds, with individual results reported in milligrams per tablet or capsule.</p><h4><strong>About Sildenafil and Tadalafil</strong></h4><p>Sildenafil and tadalafil are orally active phosphodiesterase type 5 (PDE5) inhibitors. Both compounds inhibit PDE5 and support the nitric oxide–cGMP signalling pathway involved in smooth muscle relaxation and increased blood flow.</p><p>Although they belong to the same pharmacological class, sildenafil and tadalafil differ in their pharmacokinetic profiles and duration of action. This analysis is specifically designed for products containing both compounds in a single formulation.</p><h4><strong>Key Features</strong></h4><ul><li>Targeted identification and quantification of sildenafil and tadalafil</li><li>Suitable for combined pills, tablets, and capsules</li><li>Simultaneous analysis of both target compounds</li><li>Analysis by HPLC</li><li>Results reported individually for sildenafil and tadalafil</li><li>Results reported in mg per tablet or capsule</li><li>Minimum sample amount of three tablets or capsules</li><li>Average turnaround time of 7 business days</li></ul><h4><strong>Analysis Parameters</strong></h4><ul><li><strong>Target compounds:</strong> Tadalafil and Sildenafil</li><li><strong>Testing method: </strong>HPLC</li><li><strong>Minimum amount of target compound for evaluation:</strong> 2 mg</li><li><strong>Result format: </strong>mg per tablet or capsule</li><li><strong>Minimum sample amount: </strong>Three tablets or capsules</li><li><strong>Average turnaround time: </strong>7 business days</li></ul><blockquote><p><strong>Important Notice</strong></p><ul><li>This analysis is specifically intended for products containing sildenafil and tadalafil. It does not automatically screen the sample for other PDE5 inhibitors, related compounds, contaminants, or undeclared substances.</li><li>The minimum amount of each target compound required for evaluation is 2 mg. Samples containing lower amounts may not be reliably evaluated within the standard scope of the analysis.</li></ul></blockquote><h4><strong>Optional Additional Analyses</strong></h4><p>The following optional laboratory services are available:</p><ul><li>Complete Raw Analytical Data</li><li>Batch Variance Testing</li><li>Fentanyl Screening</li><li><a target="_blank" rel="noopener noreferrer" href="https://icpms.cz/products/2525"><strong>GCMS Contamination Screening</strong></a></li><li><a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/products/2525"><strong>Heavy Metals Analysis (As, Cd, Pb, Hg)</strong></a></li><li>Additional Laboratory Report</li></ul>

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