<p><strong>Scientists at IOCB Prague are uncovering new details of gene transcription. They have identified a previously unknown molecular mechanism by which the transcription of genetic information from deoxyribonucleic acid (DNA) into ribonucleic acid (RNA) can be initiated. The researchers focused on a specific class of molecules known as alarmones, which are found in cells across a wide range of organisms and whose levels often increase under conditions of cellular stress. The results were published in the prestigious scientific journal </strong><i><strong>Nature Chemical Biology</strong></i><strong>.</strong></p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/UOCHB_Vyzkum_z_UOCHB_odhaluje_dosud_nepoznany_zpusob_prepisu_geneticke_informace_bc2bfffa6c.jpg" alt="IOCB Prague/Tomáš Belloň: Research from IOCB Prague reveals a previously unknown mechanism of genetic transcription: Dr. Hana Cahová, head of the Chemical Biology of Nucleic Acids research group." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_UOCHB_Vyzkum_z_UOCHB_odhaluje_dosud_nepoznany_zpusob_prepisu_geneticke_informace_bc2bfffa6c.jpg 234w," sizes="100vw" width="2000" height="1335"></p><div><p>Molecules of ribonucleic acid can carry a variety of chemical modifications at one end, known as caps. In eukaryotic organisms, including human cells, the best-known cap plays an important role in RNA stability and in regulating its subsequent fate. In recent years, however, it has become clear that alternative, non-canonical RNA caps also exist, although their formation and the mechanisms by which they are attached to RNA remain only partially understood. These include alarmone caps, formed by dinucleoside polyphosphate molecules, that protect cellular RNA at moments when the cell is under threat.</p><p>In their study,<strong> </strong><a target="_blank" rel="noopener noreferrer" href="https://cahova.group.uochb.cz/en"><strong>Dr. Hana Cahová</strong></a> and colleagues examined bacterial RNA polymerase and investigated how this enzyme can initiate transcription using dinucleoside polyphosphates (NpNs) instead of the standard RNA building blocks. For the first time, the scientists described, at the atomic level, how RNA bearing an alarmone cap can be generated directly at the initiation of gene transcription. They also observed that NpNs bind through a different type of base pairing than is typically observed.</p><p>The work was significantly shaped by <strong>Valentina Serianni from Hana Cahová’s team</strong>, who demonstrated the ability of dinucleoside polyphosphates to initiate gene transcription, and by <strong>Jana Škerlová</strong>, who focused on the structural analysis of RNA polymerase. Using cryogenic electron microscopy data, she showed how dinucleoside polyphosphate molecules bind within the active site of RNA polymerase – that is, the core of the enzyme where genetic information is transcribed. Together, their findings help to elucidate the processes that accompany the transcription of genetic information from DNA to RNA.</p><p>Hana Cahová adds: <i>“We’re describing something that truly occurs in cells and that we’re now able to observe directly at the level of individual molecules. This allows us to answer fundamental questions about cellular processes, such as how cells adapt to stress. RNA plays a central role in this, as it carries the cascade of information underlying any cellular response – for example, to threatening conditions caused by nutrient deprivation or temperature shock.”</i></p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/UOCHB_Vyzkum_z_UOCHB_odhaluje_dosud_nepoznany_zpusob_prepisu_geneticke_informace_2_0fe88ff9e9.jpg" alt="IOCB Prague/Tomáš Belloň: Research from IOCB Prague reveals a previously unknown mechanism of genetic transcription: Dr. Tomáš Kouba, head of the Cryogenic Electron Microscopy core facility." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_UOCHB_Vyzkum_z_UOCHB_odhaluje_dosud_nepoznany_zpusob_prepisu_geneticke_informace_2_0fe88ff9e9.jpg 234w," sizes="100vw" width="2000" height="1335"></p><div><p>Cryogenic electron microscopy (cryo-EM) was central to the project. This part of the work was led by<strong> Dr. Tomáš Kouba</strong>, one of the authors of the study. <i>“Cryogenic electron microscopy allows us to freeze biological molecules in a state very close to their natural form and then determine their three-dimensional structure. This makes it possible to look directly into the active centers of enzymes and observe their function down to the atomic level,”</i> he explains.</p><p>Last year, IOCB Prague opened a new <a target="_blank" rel="noopener noreferrer" href="https://cryoem.group.uochb.cz/en"><strong>cryo-EM center</strong></a><strong> </strong>that is unique within the Czech research environment. State-of-the-art cryogenic electron microscopes are housed in a specially designed building and enable the study of biological processes with exceptional structural precision.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/UOCHB_Vyzkum_z_UOCHB_odhaluje_dosud_nepoznany_zpusob_prepisu_geneticke_informace_3_4d881e7a58.jpg" alt="IOCB Prague: Research from IOCB Prague reveals a previously unknown mechanism of genetic transcription: This work shows how NpnNs initiate bacterial transcription. Cryo-EM reveals how nucleobases pair with the template: one in canonical and one in reverse Watson–Crick mode, providing a structural basis for their function as non-canonical RNA caps." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_UOCHB_Vyzkum_z_UOCHB_odhaluje_dosud_nepoznany_zpusob_prepisu_geneticke_informace_3_4d881e7a58.jpg 245w," sizes="100vw" width="2000" height="1077"></p><blockquote><h4><strong>The Original article</strong></h4><h4><a target="_blank" rel="noopener noreferrer" href="https://www.nature.com/articles/s41589-025-02134-5"><strong>Molecular insight into 5′ RNA capping with Np<sub>n</sub>Ns by bacterial RNA polymerase</strong></a></h4><p>Valentina M. Serianni, Jana Škerlová, Anna Knopp Dubánková, Anton Škríba, Hana Šváchová, Tereza Vučková, Anatolij Filimoněnko, Milan Fábry, Pavlína Řezáčová, Tomáš Kouba &amp; Hana Cahova&nbsp;</p><p>Nat. Chem. Biol. 21 (2026)</p><p><a target="_blank" rel="noopener noreferrer" href="https://doi.org/10.1038/s41589-025-02134-5">https://doi.org/10.1038/s41589-025-02134-5</a></p><h6>licensed under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/"><strong>CC-BY 4.0</strong></a></h6></blockquote><h4><strong>Abstract</strong></h4><p>RNA capped with dinucleoside polyphosphates has been discovered in bacteria and eukaryotes only recently. The likely mechanism of this specific capping involves direct incorporation of dinucleoside polyphosphates by RNA polymerase as noncanonical initiating nucleotides. However, how these compounds bind into the active site of RNA polymerase during transcription initiation is unknown. Here, we explored transcription initiation in vitro, using a series of DNA templates in combination with dinucleoside polyphosphates and model RNA polymerase from <i>Thermus</i> <i>thermophilus</i>. We observed that the transcription start site can vary on the basis of the compatibility of the specific template and dinucleoside polyphosphate. Cryo-electron microscopy structures of transcription initiation complexes with dinucleoside polyphosphates revealed that both nucleobase moieties can pair with the DNA template. The first encoded nucleotide pairs in a canonical Watson–Crick manner, whereas the second nucleobase pairs noncanonically in a reverse Watson–Crick manner. Our work provides a structural explanation of how dinucleoside polyphosphates initiate RNA transcription.</p></div></div>

Research from IOCB Prague reveals a previously unknown mechanism of genetic transcription

<p><strong>In the week of February 9, the following webinars await you in the field of gas / solid phase and especially Raman, FTIR, GC and GC/MS.</strong></p><blockquote><h4><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/webinars"><strong>👉 DETAILS AND REGISTRATION IN THE WEBINARS SECTION</strong></a></h4><p><strong>👉 Search and filter in the largest global database</strong> with over <strong>5 000 GC, LC, MS and spectroscopy webinars</strong>.</p></blockquote><div><div><div><div><div><div><h5><strong>1. Thermo Fisher Scientific: Process Raman – A Reliable and Versatile Tool for Downstream Process Monitoring and Control for mAb Production</strong></h5><ul><li>Tu, 10.2.2026 16:00 CET</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/webinar/5808">Registration</a></li></ul><p>The presentation highlights how process Raman spectroscopy offers several advantages over traditional in-line UV-Vis analysis for process monitoring and metabolite production control in mAb manufacturing.</p><h5><strong>2. Wasson-ECE Instrumentation: The Data Driven Plant – How AI Transforms Chemical Manufacturing</strong></h5><ul><li>Tu, 10.2.2026 21:30 CET</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/webinar/5744">Registration</a></li></ul><p>Explore how artificial intelligence is applied to improve process efficiency, monitoring, and decision-making in modern chemical manufacturing.</p><h5><strong>3. New Food Magazine: The Science of Next-Gen Ingredients – Fermentation, Formulation and Function</strong></h5><ul><li>We, 11.2.2026 16:00 CET</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/webinar/5720">Registration</a></li></ul><p>Discover how fermentation-driven innovation is transforming functional food ingredients, with analytical insights to optimize flavour, functionality, and product stability.</p></div></div></div></div></div></div>

Webinars LabRulezGCMS Week 07/2026

<p><strong>This study presents an analytical strategy combining QuEChERS extraction with low-temperature partitioning (LTP) for the determination of multiclass pesticide residues in cocoa beans by GC–MS. Extraction conditions were optimized using a fractional factorial design, resulting in a simple and efficient workflow suitable for complex cocoa matrices.</strong></p><p>The validated method showed satisfactory limits of detection and quantification, recoveries within 70–120%, and good overall performance. Application to cocoa samples from Brazil detected permethrin in several samples, demonstrating that the QuEChERS–LTP approach is an effective and reliable cleanup strategy for routine pesticide residue analysis in cocoa.</p><blockquote><h4><strong>The original article</strong></h4><h4><a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c10360"><strong>QuEChERS Combined with Low-Temperature Partitioning and GC–MS as an Analytical Strategy for the Determination of Multiclass Pesticide Residues in Cocoa Beans</strong></a></h4><p>Priscilla M. de Freitas Machado, Madson M. Nascimento, Paulo R. R. Mesquita, Manuela B. Nascimento, Lilian Lefol N. Guarieiro, Gisele O. da Rocha, Jailson B. de Andrade, Raildo M. de Jesus*</p><p>ACS Omega 2025, 10, 51, 63464–63473</p><p><a target="_blank" rel="noopener noreferrer" href="https://doi.org/10.1021/acsomega.5c10360">https://doi.org/10.1021/acsomega.5c10360</a></p><h6>licensed under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/"><strong>CC-BY 4.0</strong></a></h6></blockquote><p><strong>Selected sections from the article follow. Formats and hyperlinks were adapted from the original.</strong></p><p>Cocoa is best known as the primary raw material for chocolate but is also processed into products such as cocoa butter, biscuits, cocoa honey, and cocoa powder. Cocoa powder is derived from roasted, pressed, and milled nibs, containing on average 20% (w/w) lipids on a dry basis and less than 9% moisture. <a href="javascript:void(0);">(3,4)</a></p><p>According to the Brazilian Health Regulatory Agency (ANVISA), pesticides such as atrazine, bifenthrin, cyproconazole, metalaxyl, tebuconazole, trifloxystrobin, and permethrin are approved for use in Brazil. <a href="javascript:void(0);">(13)</a> However, among these, only metalaxyl, trifloxystrobin, and tebuconazole are authorized by the European Union. <a href="javascript:void(0);">(14)</a> Thus, investigating these contaminants in cocoa samples is of utmost importance, as Brazil is one of the largest cocoa exporters, supplying cocoa commodities to South America, the United States, and the European Union. <a href="javascript:void(0);">(2)</a> Furthermore, Organochlorine pesticides, in particular, belong to the class of persistent organic pollutants (POPs). Although banned in many countries, they continue to be used in some developing nations because of their chemical stability, resistance to degradation, volatility, and high lipophilicity, which promote bioaccumulation and neurotoxicity. <a href="javascript:void(0);">(15)</a> Epidemiological evidence also associates their exposure with Parkinson’s disease, certain cancers, diabetes, and endometriosis. <a href="javascript:void(0);">(16)</a></p><p>Residues of pesticides in cocoa have been reported in various studies. <a href="javascript:void(0);">(17)</a> Analyzing pesticide residues in cocoa presents analytical challenges due to the matrix’s complexity, comprising high lipid content, fatty acids and esters, sugars, polyphenols, and caffeine. These components can interfere with extraction efficiency and contaminate analytical instrumentation. <a href="javascript:void(0);">(18)</a> Therefore, efficient sample preparation methods incorporating effective cleanup steps are essential for accurate residue determination.</p><p>Several techniques have been employed for multiresidue pesticide analysis in cocoa. For instance, Idowu et al. <a href="javascript:void(0);">(19)</a> quantified 14 organochlorines using Soxhlet extraction and silica/Na<sub>2</sub>SO<sub>4</sub> cleanup, with GC ECD detection. Okoffo et al. <a href="javascript:void(0);">(20)</a> determined 13 organophosphates and 9 pyrethroids employing SPE cartridges (Envi-carb/LC-NH<sub>2</sub> and Bond Elute C18), acetonitrile extraction, and GC PFPD or GC ECD quantification. Yusiasih et al. <a href="javascript:void(0);">(21)</a> applied dispersive SPE with PSA, Florisil, and MgSO<sub>4</sub> for pyrethroids, followed by GC ECD and GC–MS.</p><p>Therefore, this study aimed to evaluate the effectiveness of a QuEChERS–LTP analytical procedure for the determination of multiclass pesticide residues in cocoa beans. The factors that affect the QuEChERS–LTP procedure efficiency were optimized. After validation, the procedure was employed to investigate the occurrence of 15 multiclass pesticides in cocoa samples.</p><h4><strong>Experimental Section</strong></h4><h5><strong>Instrumental Apparatus</strong></h5><p>Pesticide separation and identification were performed on a Shimadzu <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=GC-MS-QP2010SE"><strong>GC-MS-QP2010SE</strong></a> system (Kyoto, Japan) equipped with an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=AOC-20i"><strong>AOC-20i autosampler</strong></a>. Separation was achieved using an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=DB-5MS"><strong>Agilent DB-5MS capillary column</strong></a> (30 m × 0.25 mm × 0.25 μm) with a stationary phase of 5% phenyl/95% dimethylpolysiloxane. The instrumental conditions were based on Nascimento et al. <a href="javascript:void(0);">(49)</a> and they are summarized in <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c10360#tbl4">Table 4</a>.</p><p>For quantification, the base peak was used, while two additional ions were monitored for confirmation (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/suppl/10.1021/acsomega.5c10360/suppl_file/ao5c10360_si_001.pdf">Table S2</a>) in accordance with SANTE guidelines. <a href="javascript:void(0);">(50)</a> A GC–MS/SIM chromatogram illustrating the separation of all target pesticides is presented in <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c10360#fig5">Figure 5</a>.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ACS_Omega_2025_10_51_63464_63473_Figure_5_Extracted_ion_chromatogram_EIC_in_SIM_mode_of_the_target_pesticides_f2461c14f4.jpg" alt="ACS Omega 2025, 10, 51, 63464–63473: Figure 5. Extracted ion chromatogram (EIC) in SIM mode of the target pesticides obtained from the injection of a mixed standard solution at 100 μg L–1. Analytes are listed in order of elution: [1] Molinate (6.18 min); [2] α-HCH (8.15 min); [3] atrazine-d5 (8.69 min); [4] atrazine (8.75 min); [5] diazinon (9.31 min); [6] disulfoton (9.67 min); [7] dimethachlor (10.60 min); [8] metalaxyl (11.25 min); [9] p,p′-DDE (15.82 min); [10] cyproconazole I (16.50 min); [11] cyproconazole II (16.56 min); [12] p,p′-DDD (17.29 min); [13] ethion (17.34 min); [14] trifloxystrobin (18.43 min); [15] tebuconazole (19.13 min); [16] bifenthrin (20.47 min); [17] permethrin I (23.92 min); [18] permethrin II (24.18 min)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_ACS_Omega_2025_10_51_63464_63473_Figure_5_Extracted_ion_chromatogram_EIC_in_SIM_mode_of_the_target_pesticides_f2461c14f4.jpg 245w," sizes="100vw" width="2080" height="835"></p><h5><strong>Application of the Proposed Procedure to Real Samples</strong></h5><p>In a 50 mL Falcon tube, 2.0 g of sample was weighed using an analytical balance (AUX320, Shimadzu, Kyoto, Japan). A total of 2.0 g of salt (NaCl and Na<sub>2</sub>SO<sub>4</sub> in a 1:1 w/w ratio) was added, followed by an aliquot of the atrazine-<i>d</i><sub>5</sub> solution (surrogate standard) to yield a final concentration of 250 μg kg<sup>–1</sup>. A mixture of acetonitrile (8.0 mL) and ultrapure water (2.0 mL) was then added. The system was vortexed (K40-10208, Kasvi, São Paulo, Brazil) for 3.0 min at 2500 rpm and centrifuged (MPW-351R, MPW Med. Instruments, Warsaw, Poland) for 10.0 min at 15 °C and 10,000 rpm. After phase separation, approximately 6.0 mL of the supernatant was transferred to a Falcon tube containing 150.0 mg of PSA sorbent. The mixture was vortexed again for 3.0 min at 2500 rpm and centrifuged for an additional 10.0 min under the same conditions. The tubes were then placed in the freezer for 24 h. Once the aqueous phase had frozen, the organic extract containing the analytes was collected, filtered through a Cytiva Whatman MiniUniprep G2 vial with a 0.20 μm membrane filter (Marlborough, Massachusetts, USA), and injected into the GC–MS system (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c10360#fig6">Figure 6</a>).</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ACS_Omega_2025_10_51_63464_63473_Figure_6_Schematic_representation_of_the_extraction_procedure_using_the_Qu_E_Ch_ERS_LTP_procedure_for_pesticide_extraction_in_cocoa_powder_samples_ed58549bcf.jpg" alt="ACS Omega 2025, 10, 51, 63464–63473: Figure 6. Schematic representation of the extraction procedure using the QuEChERS–LTP procedure for pesticide extraction in cocoa powder samples." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_ACS_Omega_2025_10_51_63464_63473_Figure_6_Schematic_representation_of_the_extraction_procedure_using_the_Qu_E_Ch_ERS_LTP_procedure_for_pesticide_extraction_in_cocoa_powder_samples_ed58549bcf.jpg 223w," sizes="100vw" width="1458" height="1022"></p><h4><strong>Results and Discussion</strong></h4><h5><strong>Evaluation of the Effect of Low and Ultralow Temperatures on the Analytical Response</strong></h5><p>Studies reporting the use of LTP generally employ a conventional freezer, which typically reaches −18 ± 2 °C as the minimum temperature. In this equipment, effective phase separation can require 8 to 24 h. <a href="javascript:void(0);">(35−37)</a> In contrast, ultralow temperature freezers (ultrafreezers) can reach −80 °C, leading to a substantial reduction in partitioning time. In this study, tests performed with the conventional freezer achieved satisfactory partitioning after 24 h, whereas in the ultrafreezer, complete partitioning was observed in only 20 min.</p><p>Considering the analytical response in terms of peak area (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c10360#fig3">Figure 3</a>), higher signals were obtained when LTP was performed in a conventional freezer rather than an ultrafreezer. This behavior can be attributed to the partitioning mechanism. <a href="javascript:void(0);">(32)</a> Partitioning depends on cooling and the subsequent freezing of the aqueous phase. In the conventional freezer, the slower freezing rate provides sufficient time for the system to approach thermodynamic equilibrium, favoring analyte diffusion between phases. Under these conditions, analyte molecules have more time to migrate and distribute optimally before complete solidification. In contrast, the rapid freezing in the ultrafreezer may trap analytes in a nonideal distribution, reducing the efficiency of the partitioning process <a href="javascript:void(0);">(32)</a> (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c10360#fig3">Figure 3</a>). According to these observations, the conventional freezer was selected for subsequent experiments.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ACS_Omega_2025_10_51_63464_63473_Figure_3_Comparison_of_chromatographic_peak_areas_of_pesticides_after_partitioning_in_the_conventional_freezer_versus_the_ultrafreezer_9598bcfec3.jpg" alt="ACS Omega 2025, 10, 51, 63464–63473: Figure 3. Comparison of chromatographic peak areas of pesticides after partitioning in the conventional freezer versus the ultrafreezer." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_ACS_Omega_2025_10_51_63464_63473_Figure_3_Comparison_of_chromatographic_peak_areas_of_pesticides_after_partitioning_in_the_conventional_freezer_versus_the_ultrafreezer_9598bcfec3.jpg 175w," sizes="100vw" width="996" height="891"></p><h5><strong>Application to Real Samples</strong></h5><p>Fifteen samples were analyzed in triplicate, comprising two from the State of Pará and 12 from the State of Bahia, located in the North and Northeast regions of Brazil, respectively. Among the 15 pesticides investigated, only permethrin isomers were quantified in four samples (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c10360#tbl3">Table 3</a>). The herbicide molinate was also detected in three samples; however, its concentration was below LOQ. Permethrin isomers concentrations ranged from 17.1 ± 0.3 to 49.6 ± 1.8 μg kg<sup>–1</sup>. These values are below the MRL established by European Union regulation, which is 100 μg kg<sup>–1</sup>. <a href="javascript:void(0);">(42)</a> Although permethrin is not permitted in the European Union, <a href="javascript:void(0);">(42)</a> it remains authorized for use as insecticide in Brazil, particularly in crops such as cotton, rice, coffee, citrus, cabbage, beans, tobacco, maize, soybean, tomato, wheat, and grape. <a href="javascript:void(0);">(13)</a> However, no MRL values have been established for cocoa beans under Brazilian legislation. <a href="javascript:void(0);">(13)</a> <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c10360#tbl3">Table 3</a> shows the concentration of detected compounds in the cocoa samples.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/ACS_Omega_2025_10_51_63464_63473_Table_3_Mean_Concentrations_mg_kg_1_Standard_Deviation_of_Target_Pesticides_Detected_in_This_Study_2427955699.jpg" alt="ACS Omega 2025, 10, 51, 63464–63473: Table 3. Mean Concentrations (μg kg–1 ± Standard Deviation) of Target Pesticides Detected in This Study" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_ACS_Omega_2025_10_51_63464_63473_Table_3_Mean_Concentrations_mg_kg_1_Standard_Deviation_of_Target_Pesticides_Detected_in_This_Study_2427955699.jpg 196w," sizes="100vw" width="1070" height="851"></p><p>To assess method performance for pesticides not detected in the cocoa samples, one of the analyzed samples was fortified with a mixed standard solution at concentrations of 50, 250, and 500 μg kg<sup>–1</sup>. The fortified analytes were subsequently detected in the chromatograms presented in <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/suppl/10.1021/acsomega.5c10360/suppl_file/ao5c10360_si_001.pdf">Figures S2–S4</a>, indicating good response of the proposed method.</p><h4><strong>Conclusions</strong></h4><p>The QuEChERS–LTP procedure was successfully developed for the determination of 16 multiclass pesticide residues in cocoa beans. For the first time, ultralow temperature (−80 °C) was applied to accelerate the low-temperature partitioning process during pesticide extraction from cocoa beans. Nevertheless, conventional freezing at −12 °C proved to be more effective for the extraction of the target analytes.</p><p>Evaluation of the matrix effect demonstrated that matrix-matched analytical curves, constructed in an analyte-free cocoa bean extract, were more effective in compensating for matrix interferences than the use of analyte protectants.</p><p>The pyrethroid permethrin was quantified in four cocoa samples. However, the concentrations did not exceed the MRL established by European Union legislation.</p><p>Overall, the QuEChERS–LTP procedure proved to be a promising approach for pesticide residue determination, as it requires smaller volumes of solvents and reagents, involves fewer cleanup and extraction steps, and shows strong potential for application to other complex matrices.</p>

QuEChERS Combined with Low-Temperature Partitioning and GC–MS as an Analytical Strategy for the Determination of Multiclass Pesticide Residues in Cocoa Beans

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The Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences (IOCB Prague) is a leading scientific institution in the Czech Republic, recognized internationally. Its primary mission is basic research in the fields of chemical biology and medicinal chemistry, organic and material oriented chemistry, chemistry of natural compounds, biochemistry and molecular biology, physical chemistry, theoretical chemistry, and analytical chemistry. 

Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences

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Start your analysis with confidence using SureSTART vials, caps, well plates, and kits—offering full compatibility, quality materials, and performance across three levels.

<h4><strong>Streamlined choice. Trusted quality.</strong></h4><p><strong>Start your analysis with confidence using Thermo Scientific™ SureSTART™ vials, caps, inserts, well plates, mats, and certified kits designed to meet your analytical, regulatory, and performance requirements. With full instrument compatibility, high material quality, and consistent performance across three defined levels, the SureSTART collection offers a smarter way to choose the right sample containment solution for your workflow.</strong></p><h3><strong>Why choose SureSTART?</strong></h3><ul><li><strong>Proven reliability</strong>: Every product is manufactured and certified to meet physical specifications—no weak links in your workflow.</li><li><strong>Clear selection</strong>: Three performance levels help you balance sensitivity, robustness, and cost, now visually marked with one, two, or three waves on the vial.</li><li><strong>Universal compatibility</strong>: Designed for seamless integration with all major GC, HPLC/UHPLC, and MS autosamplers across all vendors.</li><li><strong>Certified cleanliness</strong>: Products are manufactured using the purest glass and plastics with low extractables and leachables, including GOLD-grade and silanized glass.</li><li><strong>Maximum sample integrity</strong>: Minimize analyte loss and background peaks with precision-engineered sealing, surface chemistry, and material composition.</li><li><strong>Bulk savings &amp; simplified inventory</strong>: Available in multiple pack sizes, performance levels, and formats to support your lab’s needs and budget.</li></ul><h3><strong>The Three Performance Levels</strong></h3><ul><li><strong>Level 1 – Everyday analysis</strong>: For general-purpose GC/HPLC detection (e.g. UV/Vis, FID, RI). These chromatography-approved products are ideal for routine analyses with cost-efficiency in mind.</li><li><strong>Level 2 – High-throughput analysis</strong>: Designed for regulated labs requiring robust and reproducible data, especially when using MS detectors for routine quantification.</li><li><strong>Level 3 – High performance</strong>: For the most sensitive and selective analyses near the method detection limit. Packed in cleanroom environments and made with ultra-pure materials for maximum sample security and MS compatibility.</li></ul><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Thermo_Scientific_Sure_START_Vials_and_Well_Plates_Collection_5a8b0da936.jpg" alt="Thermo Scientific SureSTART Vials and Well Plates Collection: Three performance levels help you balance sensitivity, robustness, and cost, now visually marked with one, two, or three waves on the vial." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Thermo_Scientific_Sure_START_Vials_and_Well_Plates_Collection_5a8b0da936.jpg 245w," sizes="100vw" width="1182" height="270"></p><h3><strong>SureSTART Certified Vial and Cap Kits</strong></h3><ul><li><strong>Specification Certified</strong>: Routine analyses – Certified for physical specifications; no individual certificate.</li><li><strong>LC/GC Certified</strong>: Chromatography-grade – Tested for 15 physical parameters with LC-UV &amp; GC-FID; certificate included.</li><li><strong>MSCERT</strong>: For LC-MS/GC-MS – Certified low-adsorption kits tested with MS; includes SureStop™ vials with AVCS™ caps.</li><li><strong>MSCERT+</strong>: For trace-level MS or DIA – Pre-cleaned, tested with LC-MS/GC-MS, and sold only as kits to ensure purity.</li><li><strong>Application Certified</strong>: Pre-matched kits for specific instruments or validated applications.</li></ul><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Thermo_Scientific_Sure_START_Vials_and_Well_Plates_Collection_2_fef6049d71.jpg" alt="Thermo Scientific SureSTART Vials and Well Plates Collection: There are several factors to consider when choosing a vial or well plate for your application. The table below will help guide you through this process to determine what type of product/performance level is most suitable for your application requirements." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Thermo_Scientific_Sure_START_Vials_and_Well_Plates_Collection_2_fef6049d71.jpg 204w," sizes="100vw" width="1515" height="1159"></p><h3><strong>SureSTART Well Plates and Mats</strong></h3><p>Thermo Scientific™ WebSeal™ well plates are ideal for laboratories seeking to increase autosampler capacity, reduce solvent usage, and streamline high-throughput workflows. Available in <strong>96- and 384-well formats</strong>, they offer a certified alternative to traditional vials and are fully compatible with automated SPE/SLE platforms.</p><ul><li><strong>Space-saving efficiency</strong>: Replace vials with well plates to increase sample capacity up to 8× and reduce storage footprint.</li><li><strong>Flexible performance levels</strong>:<ul><li><strong>Level 1: Standard plates for routine</strong>, non-regulated use (GC-tested).</li><li><strong>Level 2: Low-bleed plates and high-performance mats</strong>, validated for LC-MS/GC-MS.</li><li><strong>Level 3: Premium WebSeal Plate+</strong> with glass-coated plastic wells—ideal for trace analytes and protein adsorption control.</li></ul></li><li><strong>Solvent stability and clean sample contact</strong>: WebSeal Plate+ uses nanolayered silicon dioxide for minimal extractables and ultra-low adsorption.</li><li><strong>Compatible sealing options</strong>:<ul><li><strong>Silicone mats: </strong>For long-term storage and consistent results.</li><li><strong>Pre-slit mats: </strong>For autosampler injection without evaporation or contamination.</li><li><strong>Adhesive seals: </strong>For single-use workflows and re-sealing options with cavity protection.</li></ul></li></ul><p>Whether you work with polar solvents, proteins, or trace-level analyses, SureSTART well plates and sealing accessories help you optimize throughput, precision, and data confidence across all chromatography workflows.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Thermo_Scientific_Sure_START_Vials_and_Well_Plates_Collection_3_abce3dd960.jpg" alt="Thermo Scientific SureSTART Vials and Well Plates Collection: Selecting the perfect Thermo Scientific WebSeal well plates and mats for your chromatography requirements is easy using our selector tools and resources." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Thermo_Scientific_Sure_START_Vials_and_Well_Plates_Collection_3_abce3dd960.jpg 245w," sizes="100vw" width="1516" height="902"></p>

Thermo Scientific QuEChERS Sample Preparation Kits

QuEChERS is a versatile sample preparation method for analyzing pesticides, veterinary drugs, and other residues in various sample types before GC-MS or LC-MS analysis.

<div><div><div><h3><strong>QuEChERS sample preparation—now easier, more convenient, and affordable</strong></h3><p><strong>QuEChERS</strong> (<strong><u>Q</u></strong><u>u</u>ick, <strong><u>E</u></strong>asy, <strong><u>C</u></strong>heap, <strong><u>E</u></strong>ffective, <strong><u>R</u></strong>ugged, and <strong><u>S</u></strong>afe)is a <strong>sample preparation method</strong> that was initially developed in 2003 for <strong>analyzing veterinary drugs in food</strong>. The method was also tested for <strong>pesticide residue analysis in plant material</strong> with great success. In 2003, the <strong>detailed method was published</strong> in the journal AOAC International. Since then, the QuEChERS method has evolved into a <strong>sample preparation technique used on a variety of analytes</strong> in an <strong>expanding number of sample types</strong> before analysis by <a target="_blank" rel="noopener noreferrer" href="https://www.thermofisher.com/cz/en/home/industrial/mass-spectrometry/gas-chromatography-mass-spectrometry-gc-ms.html"><strong>GC-MS</strong></a><strong> or </strong><a target="_blank" rel="noopener noreferrer" href="https://www.thermofisher.com/cz/en/home/industrial/mass-spectrometry/liquid-chromatography-mass-spectrometry-lc-ms.html"><strong>LC-MS</strong></a>.</p><p><strong>Thermo Scientific QuEChERS kits</strong> contain <strong>pre-packaged, ready-weighed salts, sorbents, and buffers</strong> to <strong>streamline your workflow</strong> and <strong>minimize the potential for error</strong>. The kits are grouped according to your <strong>analytes of interest</strong>, <strong>sample matrix</strong>, and <strong>preferred QuEChERS method</strong>:</p><ul><li><strong>Original 2003 Method</strong></li><li><strong>AOAC 2007.01 Method</strong></li><li><strong>EN 15662 Method</strong></li><li><strong>NY/T 1380-2007 Method</strong></li></ul><p><strong>Complete packages</strong>—including both <strong>extraction and clean-up kits</strong>—are available. <strong>Extraction-only and cleanup-only kits</strong> are also offered to suit your laboratory’s sample preparation needs. These <strong>pre-packaged kits save time and money</strong>, make QuEChERS procedures <strong>easier and more convenient</strong>, and ensure <strong>quality to yield reproducible results</strong> and <strong>excellent recoveries</strong> for a wide variety of analytes.</p><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Thermo_Scientific_Qu_E_Ch_ERS_Sample_Preparation_Kits_2_1e99f0c81b.jpg" alt="Thermo Scientific QuEChERS Sample Preparation Kits" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Thermo_Scientific_Qu_E_Ch_ERS_Sample_Preparation_Kits_2_1e99f0c81b.jpg 217w," sizes="100vw" width="891" height="640"></p><h3><strong>Typical QuEChERS workflow</strong></h3><div><div><div><div><div><p>As shown in the workflow diagram below, the <strong>QuEChERS method has four basic steps</strong>:</p><ol><li><strong>Homogenize sample</strong> (fruit or vegetable)</li><li><strong>Extract analytes of interest</strong> from a sample using <strong>extraction salts</strong> (pesticide residues, veterinary drugs, and/or mycotoxins)</li><li><strong>Clean-up the resulting supernatant</strong> using <strong>dispersive solid phase extraction (dSPE)</strong></li><li><strong>Analyze by GC-MS or LC-MS</strong></li></ol><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Thermo_Scientific_Qu_E_Ch_ERS_Sample_Preparation_Kits_496491ceff.jpeg" alt="Thermo Scientific QuEChERS Sample Preparation Kits" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Thermo_Scientific_Qu_E_Ch_ERS_Sample_Preparation_Kits_496491ceff.jpeg 245w," sizes="100vw" width="1170" height="706"></p><div><h3><strong>QuEChERS products</strong></h3></div><div><h4><strong>QuEChERS extraction kits for original 2003 method</strong></h4></div><div><p>The <strong>original QuEChERS method</strong> (Anastassiades et al, 2003) was developed by <strong>Steven J. Lehotay and Michelangelo Anastassiades</strong> in 2003 for the <strong>determination of pesticide residues in fruits and vegetables</strong>. The original method was created to <strong>analyze non-base-sensitive compounds</strong> and uses a <strong>sodium chloride buffer</strong> to <strong>reduce polar interferences</strong> and <strong>enhance extraction</strong>. <strong>Buffering</strong> is an important part of the QuEChERS procedure because it <strong>allows for analysis of pesticides and other residues</strong> that display <strong>pH dependence in their recoveries</strong>, depending on the <strong>sample matrix</strong>. <strong>Three different extraction kits</strong> are available to support the <strong>original 2003 QuEChERS method</strong>.</p><h5><strong>Chemicals used in the original 2003 method</strong></h5></div><ul><li><strong>Acetonitrile:</strong> Used to perform single-phase extraction (SPE) on a sample</li><li><strong>Anhydrous MgSO₄:</strong> Induces phase separation between water content in sample and acetonitrile layer during liquid-liquid partitioning step; removes remaining water from sample during dispersive solid phase extraction (dSPE) step</li><li><strong>NaCl:</strong> Induces phase separation between water content in sample and acetonitrile layer during liquid-liquid partitioning step; removes residual water from sample; reduces polar interference and enhances extraction</li><li><strong>PSA:</strong> Primary secondary amine, used to remove polar matrix components, citric co-extractives, and free fatty acids, from sample during dispersive solid phase extraction (dSPE) step</li></ul><div><h4><strong>QuEChERS extraction and clean-up kits for AOAC 2007.01 method</strong></h4><p>The <strong>AOAC 2007.01 QuEChERS Method</strong> was developed by <strong>Steven J. Lehotay and his co-workers</strong>, who <strong>modified the original 2003 method</strong> to accommodate the use of <strong>acetate buffering at higher concentration</strong> for <strong>greater buffering strength</strong>. <strong>Buffering</strong> is an important part of the QuEChERS procedure because it <strong>allows for analysis of pesticides and other residues</strong> that display <strong>pH dependence in their recoveries</strong>, depending on the <strong>sample matrix</strong>. These <strong>extraction and clean-up products</strong> here support the <strong>AOAC 2007.01 method</strong>.</p><div><h5><strong>Chemicals used in the AOAC 2007.01 method</strong></h5><ul><li><strong>Acetonitrile:</strong> Used to perform single-phase extraction on a sample</li><li><strong>Anhydrous MgSO₄:</strong> Induces phase separation between water content in sample and acetonitrile layer during liquid-liquid partitioning step; removes remaining water from sample during dispersive solid phase extraction (dSPE) step</li><li><strong>NaOAc:</strong> Buffers the sample to stabilize pH</li><li><strong>PSA:</strong> Primary secondary amine, used to remove polar matrix components, citric co-extractives, and free fatty acids, from sample during dispersive solid phase extraction (dSPE) step</li><li><strong>C18:</strong> Removes fats, sterols, and other non-polar interferences from sample</li><li><strong>GCB:</strong> Graphitized carbon black, removes pigment (<i>not recommended for use with planar pesticides</i>)</li></ul><div><h4><strong>QuEChERS extraction and clean-up kits for EN 15662 method</strong></h4><p>The <strong>extraction and clean-up products</strong> here support the <strong>EN 15662 method</strong>. <strong>Widely used in Europe</strong>, the EN 15662 method was developed by <strong>Michelangelo Anastassiades and co-workers</strong>, who <strong>modified the original 2003 method</strong> to accommodate the use of <strong>citrate buffering at a relatively low buffering capacity</strong>. This variation uses a <strong>sodium chloride buffer</strong> to <strong>minimize polar interferences</strong> in addition to <strong>sodium citrate dihydrate</strong> and <strong>disodium citrate sesquihydrate buffers</strong>. <strong>Buffering</strong> is an important part of the QuEChERS procedure because it <strong>allows for analysis of pesticides and other residues</strong> that display <strong>pH dependence in their recoveries</strong>, depending on the <strong>sample matrix</strong>.</p><h5><strong>Chemicals used in the EN 15662 method</strong></h5><ul><li><strong>Acetonitrile:</strong> Used to perform single-phase extraction on a sample</li><li><strong>Anhydrous MgSO₄:</strong> Induces phase separation between water content in sample and acetonitrile layer during liquid-liquid partitioning step; removes remaining water from sample during dispersive solid phase extraction (dSPE) step</li><li><strong>NaCl:</strong> Induces phase separation between water content in sample and acetonitrile layer during liquid-liquid partitioning step; removes residual water from sample</li><li><strong>Trisodium Citrate:</strong> Buffers the sample to stabilize pH</li><li><strong>Disodium Citrate Sesquihydrate:</strong> Buffers the sample to stabilize pH</li><li><strong>PSA:</strong> Primary secondary amine, used to remove polar matrix components, citric co-extractives, and free fatty acids, from sample during dispersive solid phase extraction (dSPE) step</li><li><strong>C18:</strong> Removes fats, sterols, and other non-polar interferences from sample</li><li><strong>GCB:</strong> Graphitized carbon black, removes pigment (<i>not recommended for use with planar pesticides</i>)</li></ul><p><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Thermo_Scientific_Qu_E_Ch_ERS_Sample_Preparation_Kits_3_721562526f.jpg" alt="Thermo Scientific QuEChERS Sample Preparation Kits" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Thermo_Scientific_Qu_E_Ch_ERS_Sample_Preparation_Kits_3_721562526f.jpg 245w," sizes="100vw" width="1471" height="488"></p><div><h4><strong>QuEChERS clean-up kit for NY/T 1380-2007 method</strong></h4></div><div><p>The <strong>NY/T 1380-2007 method</strong> is <strong>recommended by China Ministry of Agriculture</strong> for the <strong>QuEChERS Method sample preparation</strong> of <strong>51 specific pesticide residues</strong> in <strong>fruits and vegetables</strong> with <strong>analysis by GC-MS</strong>.</p><h5><strong>Chemicals used in the NY/T 1380-2007 method</strong></h5><ul><li><strong>Anhydrous MgSO₄:</strong> Induces phase separation between water content in sample and acetonitrile layer during liquid-liquid partitioning step; removes remaining water from sample during dispersive solid phase extraction (dSPE) step</li><li><strong>PSA:</strong> Primary secondary amine, used to remove polar matrix components, citric co-extractives, and free fatty acids, from sample during dSPE step</li><li><strong>C18:</strong> Removes fats, sterols, and other non-polar interferences from sample</li></ul></div></div></div></div></div></div></div></div></div></div></div></div>

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