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 Nature Chemical Biology.<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"><div>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.In their study, <a target="_blank" rel="noopener noreferrer" href="https://cahova.group.uochb.cz/en">Dr. Hana Cahová</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.The work was significantly shaped by Valentina Serianni from Hana Cahová’s team, who demonstrated the ability of dinucleoside polyphosphates to initiate gene transcription, and by Jana Škerlová, 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.Hana Cahová adds: “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.”<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"><div>Cryogenic electron microscopy (cryo-EM) was central to the project. This part of the work was led by Dr. Tomáš Kouba, one of the authors of the study. “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,” he explains.Last year, IOCB Prague opened a new <a target="_blank" rel="noopener noreferrer" href="https://cryoem.group.uochb.cz/en">cryo-EM center</a> 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.<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"><blockquote><h4>The Original article</h4><h4><a target="_blank" rel="noopener noreferrer" href="https://www.nature.com/articles/s41589-025-02134-5">Molecular insight into 5′ RNA capping with NpnNs by bacterial RNA polymerase</a></h4>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;Nat. Chem. Biol. 21 (2026)<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><h6>licensed under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/">CC-BY 4.0</a></h6></blockquote><h4>Abstract</h4>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 Thermus thermophilus. 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.</div></div>

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

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.<blockquote><h4><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/webinars">👉 DETAILS AND REGISTRATION IN THE WEBINARS SECTION</a></h4>👉 Search and filter in the largest global database with over 5 000 GC, LC, MS and spectroscopy webinars.</blockquote><div><div><div><div><div><div><h5>1. Thermo Fisher Scientific: Process Raman – A Reliable and Versatile Tool for Downstream Process Monitoring and Control for mAb Production</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>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.<h5>2. Wasson-ECE Instrumentation: The Data Driven Plant – How AI Transforms Chemical Manufacturing</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>Explore how artificial intelligence is applied to improve process efficiency, monitoring, and decision-making in modern chemical manufacturing.<h5>3. New Food Magazine: The Science of Next-Gen Ingredients – Fermentation, Formulation and Function</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>Discover how fermentation-driven innovation is transforming functional food ingredients, with analytical insights to optimize flavour, functionality, and product stability.</div></div></div></div></div></div>

Webinars LabRulezGCMS Week 07/2026

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.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.<blockquote><h4>The original article</h4><h4><a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/10.1021/acsomega.5c10360">QuEChERS Combined with Low-Temperature Partitioning and GC–MS as an Analytical Strategy for the Determination of Multiclass Pesticide Residues in Cocoa Beans</a></h4>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*ACS Omega 2025, 10, 51, 63464–63473<a target="_blank" rel="noopener noreferrer" href="https://doi.org/10.1021/acsomega.5c10360">https://doi.org/10.1021/acsomega.5c10360</a><h6>licensed under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/">CC-BY 4.0</a></h6></blockquote>Selected sections from the article follow. Formats and hyperlinks were adapted from the original.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>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>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.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/Na2SO4 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-NH2 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 MgSO4 for pyrethroids, followed by GC ECD and GC–MS.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.<h4>Experimental Section</h4><h5>Instrumental Apparatus</h5>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">GC-MS-QP2010SE</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">AOC-20i autosampler</a>. Separation was achieved using an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=DB-5MS">Agilent DB-5MS capillary column</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>.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>.<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"><h5>Application of the Proposed Procedure to Real Samples</h5>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 Na2SO4 in a 1:1 w/w ratio) was added, followed by an aliquot of the atrazine-d5 solution (surrogate standard) to yield a final concentration of 250 μg kg–1. 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>).<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"><h4>Results and Discussion</h4><h5>Evaluation of the Effect of Low and Ultralow Temperatures on the Analytical Response</h5>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.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.<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"><h5>Application to Real Samples</h5>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–1. These values are below the MRL established by European Union regulation, which is 100 μg kg–1. <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.<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">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–1. 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.<h4>Conclusions</h4>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.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.The pyrethroid permethrin was quantified in four cocoa samples. However, the concentrations did not exceed the MRL established by European Union legislation.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.

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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Phenomenex Strata SAX Solid Phase Extraction (SPE)

The quaternary amine group on this sorbent remains positively charged under all conditions, giving a strong anion-exchange mechanism of retention.

Ion-Exchange Solid Phase Extraction Sorbent (SPE)The quaternary amine group on this sorbent remains positively charged under all conditions, giving a strong anion-exchange mechanism of retention.<figure class="image"><img style="aspect-ratio:500/150;" src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_sax_470d923b27.webp" alt="Phenomenex: Strata-SAX" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_sax_470d923b27.webp 245w," sizes="100vw" width="500" height="150"></figure><ul><li>Surface Area (m²/g): -</li><li>Separation Mode: Ion Exchange</li><li>Particle Size: 55</li><li>Recommended Use: Extraction of weakly acidic compounds</li></ul><h4>Starting Method</h4><h5>Strata SAX – Strong Anion-Exchange</h5><ul><li>Condition: 1 mL Methanol</li><li>Equilibrate: 1 mL DI Water</li><li>Load: Pretreated sample, pH 6-7</li><li>Wash 1: 1 mL 25mM Ammonium Acetate Buffer, pH 6-7</li><li>Wash 2: 1 mL Methanol, dry under vacuum for 2-5 min</li><li>Elute: 1 mL 5% Formic Acid in Methanol</li></ul>Based on 100 mg/1 mL sorbent mass. The above is a convenient starting point for SPE method development, further optimization may be required to tailor the method for your specific extraction needs.

Phenomenex Strata Screen-A Solid Phase Extraction (SPE)

Incorporates the hydrophobic selectivity of a C8 phase and strong anion-exchange for the extraction of acidic drugs from biological matrices.

Mixed-Mode Solid Phase Extraction (SPE) SorbentIncorporates the hydrophobic selectivity of a C8 phase and strong anion-exchange for the extraction of acidic drugs from biological matrices.<figure class="image"><img style="aspect-ratio:500/150;" src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_Screen_A_f370bdfd48.webp" alt="Phenomenex: Strata Screen-A" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_Screen_A_f370bdfd48.webp 245w," sizes="100vw" width="500" height="150"></figure><ul><li>Surface Area (m²/g): -</li><li>Separation Mode: Multi-Mode</li><li>Particle Size: 55</li><li>Recommended Use: Extracts acidic drugs from biological matrices</li></ul><h4>Starting Method</h4><h5>Strata Screen-A Strong Anion-Exchange</h5><ul><li>Condition: 1 mL Methanol</li><li>Equilibrate: 1 mL Water</li><li>Load: Pretreated sample</li><li>Wash 1: 1 mL 25mM Ammonium Acetate Buffer, pH 6-7</li><li>Wash 2: 1 mL Methanol, dry under vacuum for 2-5 min</li><li>Elute: 1 mL 5% Formic Acid in Methanol</li></ul>Based on 100 mg/1 mL sorbent mass. The above is a convenient starting point for SPE method development, further optimization may be required to tailor the method for your specific extraction needs.

Phenomenex Strata Screen-C Solid Phase Extraction (SPE)

Incorporates the hydrophobic selectivity of a C8 phase and strong cation exchange for the extraction of basic drugs from biological matrices.

Strong Cation-Exchange Solid Phase Extraction (SPE)Incorporates the hydrophobic selectivity of a C8 phase and strong cation exchange for the extraction of basic drugs from biological matrices.<figure class="image"><img style="aspect-ratio:500/150;" src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_Screen_C_b60bb2b7e4.webp" alt="Phenomenex: Strata Screen-C" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_Screen_C_b60bb2b7e4.webp 245w," sizes="100vw" width="500" height="150"></figure><ul><li>Surface Area (m²/g): 500, m²/g, 500 m²/g</li><li>Separation Mode: Multi-Mode</li><li>Pore Size: 70</li><li>Particle Size: 55</li><li>Recommended Use: Extraction of basic drugs from biological matrixes</li></ul><h4>Starting Method</h4><h5>Strata Screen-C Strong Cation-Exchange</h5><ul><li>Condition: 1 mL Methanol</li><li>Equilibrate: 1 mL Acidified Water</li><li>Load: Pretreated sample (acidified)</li><li>Wash 1: 1 mL 0.1N HCl in Water</li><li>Wash 2: 1 mL 0.1N HCl in Methanol, dry under vacuum for 2-5 min</li><li>Elute: 1 mL 5 % NH4OH in Methanol</li></ul>Based on 100 mg/1 mL sorbent mass. The above is a convenient starting point for SPE method development, further optimization may be required to tailor the method for your specific extraction needs.

Phenomenex Strata Screen-C GF Solid Phase Extraction (SPE)

Optimized for gravity flow, this sorbent offers hydrophobic selectivity from a C8 phase and strong cation-exchange properties for the extraction of basic drugs.

Strong Cation-Exchange Solid Phase Extraction (SPE)Optimized for gravity flow, this sorbent offers hydrophobic selectivity from a C8 phase and strong cation-exchange properties for the extraction of basic drugs from biological matrixes. Offers the selectivity of Screen-C in a gravity flow particle size for viscous samples.<h4>Starting Method</h4><h5>Strata Screen-C GF Strong Cation-Exchange</h5><ul><li>Condition: 1 mL Methanol</li><li>Equilibrate: 1 mL Acidified Water</li><li>Load: Pretreated sample (acidified)</li><li>Wash 1: 1 mL 0.1N HCl in Water</li><li>Wash 2: 1 mL 0.1N HCl in Methanol, dry under vacuum for 2-5 min</li><li>Elute: 1 mL 5 % NH4OH in Methanol</li></ul>Based on 100 mg/1 mL sorbent mass. The above is a convenient starting point for SPE method development, further optimization may be required to tailor the method for your specific extraction needs.

Phenomenex Strata X-AW Solid Phase Extraction (SPE)

Strata-X-AW mixed-mode SPE sorbent enables strong retention of acids (pKa ≤5) with 100% organic wash, ensuring maximum removal of interferences for clean, reliable extractions.

Weak Anion Mixed-Mode Solid Phase Extraction (SPE)A weak anion-exchange functionalized polymeric sorbent that allows for complete retention of acidic compounds with a pKa less than 5, making 100% organic wash conditions possible. A 100% organic wash ensures that the maximum amount of interferences are removed from the target compound.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_AW_SPE_cd5908db4d.jpg" alt="Phenomenex: Strata-X-AW SPE" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_AW_SPE_cd5908db4d.jpg 245w," sizes="100vw" width="500" height="268"><ul><li>Recommended Use: Extraction of acidic compounds, particularly strong acids</li></ul><h4>Starting Method</h4><h5>For Acids with pKa ≤ 5</h5><ul><li>Column: 1 mL Methanol</li><li>Equilibrate: 1 mL Water, pH 6-7</li><li>Load: Diluted Sample pH 6-7</li><li>Wash 1: 1 mL 25 mM Ammonium Acetate Buffered, pH 6-7</li><li>Wash 2: 1 mL Methanol</li><li>Elute Any Acid: 2x 500 µL 5 % NH4OH in Methanol</li><li>Elute Weak Acids: 2x 500 µL 5 % Formic Acid in Methanol</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_single_tube_435d45d0ad.jpg" alt="Phenomenex: Strata X single tube" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_single_tube_435d45d0ad.jpg 156w," sizes="100vw" width="1080" height="1080">Based on 30 mg/1 mL sorbent mass. The above is a convenient starting point for SPE method development, further optimization may be required to tailor the method for your specific extraction needs.<h4>Available Formats</h4><ul><li>96-Well-Plate</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_96_well_plate_9a66005814.jpg" alt="Phenomenex: Strata X 96-well plate" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_96_well_plate_9a66005814.jpg 156w," sizes="100vw" width="1080" height="1080"><ul><li>1, 3, and 6mL Tubes</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_tubes_1_9b04cab6c1.jpg" alt="Phenomenex: Strata X 1, 3, and 6mL Tubes" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_tubes_1_9b04cab6c1.jpg 156w," sizes="100vw" width="1080" height="1080"><ul><li>Giga Tubes (12-150mL Tubes)</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_tubes_2_a8cd1706ec.jpg" alt="Phenomenex: Strata X Giga Tubes (12-150mL Tubes)" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_tubes_2_a8cd1706ec.jpg 156w," sizes="100vw" width="1080" height="1080">

Phenomenex Strata X-A Solid Phase Extraction (SPE)

Strata-X-A strong anion-exchange SPE retains weak acids (pKa >2) with 100% organic wash, maximizing interference removal. Available in tubes, plates, and giga formats.

Strong Anion Mixed-Mode Solid Phase Extraction (SPE)A strong anion-exchange functionalized polymeric sorbent that allows for complete retention of weakly acidic compounds with a pKa greater than 2, making 100% organic wash conditions possible. A 100% organic wash ensures that the maximum amount of interferences are removed from the target compound.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_A_SPE_e107f0b6bf.jpg" alt="Phenomenex: Strata-X-A SPE" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_A_SPE_e107f0b6bf.jpg 245w," sizes="100vw" width="500" height="268"><ul><li>Recommended Use: Extraction of weakly acidic compounds</li></ul><h4>Starting Method</h4><h5>For Acids with pKa &gt; 2</h5><ul><li>Column: 1 mL Methanol</li><li>Equilibrate: 1 mL Water, pH 6-7</li><li>Load: Diluted Sample pH 6-7</li><li>Wash 1: 1 mL 25 mM Ammonium Acetate Buffered, pH 6-7</li><li>Wash 2: 1 mL Methanol (collect this fraction to analyze Neutral/Bases)</li><li>Elute Acid: 2x 500 µL 5 % Formic Acid in Methanol</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_single_tube_435d45d0ad.jpg" alt="Phenomenex: Strata X single tube" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_single_tube_435d45d0ad.jpg 156w," sizes="100vw" width="1080" height="1080">Based on 30 mg/1 mL sorbent mass. The above is a convenient starting point for SPE method development, further optimization may be required to tailor the method for your specific extraction needs.<h4>Available Formats</h4><ul><li>96-Well-Plate</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_96_well_plate_9a66005814.jpg" alt="Phenomenex: Strata X 96-well plate" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_96_well_plate_9a66005814.jpg 156w," sizes="100vw" width="1080" height="1080"><ul><li>1, 3, and 6mL Tubes</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_tubes_1_9b04cab6c1.jpg" alt="Phenomenex: Strata X 1, 3, and 6mL Tubes" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_tubes_1_9b04cab6c1.jpg 156w," sizes="100vw" width="1080" height="1080"><ul><li>Giga Tubes (12-150mL Tubes)</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_tubes_2_a8cd1706ec.jpg" alt="Phenomenex: Strata X Giga Tubes (12-150mL Tubes)" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_tubes_2_a8cd1706ec.jpg 156w," sizes="100vw" width="1080" height="1080">

Phenomenex Strata X-C Solid Phase Extraction (SPE)

Strata-X-C strong cation-exchange SPE retains basic compounds (pKa ≤10.5) with 100% organic wash for maximum cleanup. Offered in tubes, plates, and giga formats.

Strong Cation Mixed-Mode Solid Phase Extraction (SPE)A strong cation-exchange functionalized polymeric sorbent that allows for complete retention of basic compounds with a pKa less than 10.5, making 100% organic wash conditions possible. A 100% organic wash ensures that the maximum amount of interferences are removed from the target compound.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_C_SPE_4927d7340d.jpg" alt="Phenomenex: Strata-X-C SPE" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_C_SPE_4927d7340d.jpg 245w," sizes="100vw" width="500" height="268"><ul><li>Recommended Use: Extraction of weakly basic compounds</li></ul><h4>Starting Method</h4><h5>For Bases with pKa ≤ 10.5</h5><ul><li>Column: 1 mL Methanol</li><li>Equilibrate: 1 mL Acidified Water</li><li>Load: Diluted Acidified Sample</li><li>Wash 1: 1 mL 0.1 N HCI in Water (collect this fraction to analyze Polar Neutrals)</li><li>Wash 2: 1 mL 0.1 N HCI in Methanol (collect this fraction to analyze Neutrals/Acids)</li><li>Elute Bases: 2x 500 µL 5 % NH4OH in Methanol</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_single_tube_435d45d0ad.jpg" alt="Phenomenex: Strata X single tube" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_single_tube_435d45d0ad.jpg 156w," sizes="100vw" width="1080" height="1080">Based on 30 mg/1 mL sorbent mass. The above is a convenient starting point for SPE method development, further optimization may be required to tailor the method for your specific extraction needs.<h4>Available Formats</h4><ul><li>96-Well-Plate</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_96_well_plate_9a66005814.jpg" alt="Phenomenex: Strata X 96-well plate" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_96_well_plate_9a66005814.jpg 156w," sizes="100vw" width="1080" height="1080"><ul><li>1, 3, and 6mL Tubes</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_tubes_1_9b04cab6c1.jpg" alt="Phenomenex: Strata X 1, 3, and 6mL Tubes" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_tubes_1_9b04cab6c1.jpg 156w," sizes="100vw" width="1080" height="1080"><ul><li>Giga Tubes (12-150mL Tubes)</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_tubes_2_a8cd1706ec.jpg" alt="Phenomenex: Strata X Giga Tubes (12-150mL Tubes)" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_tubes_2_a8cd1706ec.jpg 156w," sizes="100vw" width="1080" height="1080">

Phenomenex Strata X-CW Solid Phase Extraction (SPE)

Strata-X-CW weak cation-exchange SPE retains strong bases (pKa >8) with 100% organic wash for maximum cleanup. Available in tubes, 96-well plates, and giga formats.

Weak Cation Mixed-Mode Solid Phase Extraction (SPE)A weak cation-exchange functionalized polymeric sorbent that allows for complete retention of basic compounds with a pKa greater than 8, making 100% organic wash conditions possible. A 100% organic wash ensures that the maximum amount of interferences are removed from the target compound.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_CW_SPE_b16a0e0baf.jpg" alt="Phenomenex: Strata-X-CW SPE" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_CW_SPE_b16a0e0baf.jpg 245w," sizes="100vw" width="500" height="268"><ul><li>Recommended Use: Extraction of basic compounds, particularly strong bases</li></ul><h4>Starting Method</h4><h5>For Bases with pKa &gt; 8</h5><ul><li>Column: 1 mL Methanol</li><li>Equilibrate: 1 mL Water, pH 6-7</li><li>Load: Diluted Sample, pH 6-7</li><li>Wash 1: 1 mL Water, pH 6-7</li><li>Wash 2: 1 mL Methanol (collect this fraction to analyze Neutrals/Acids)</li><li>Elute Any Bases: 2x 500 µL 5 % Formic Acid in Methanol</li><li>Elute Weak Bases: 2x 500 µL 5 % NH4OH in Methanol</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_single_tube_435d45d0ad.jpg" alt="Phenomenex: Strata X single tube" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_single_tube_435d45d0ad.jpg 156w," sizes="100vw" width="1080" height="1080">Based on 30 mg/1 mL sorbent mass. The above is a convenient starting point for SPE method development, further optimization may be required to tailor the method for your specific extraction needs.<h4>Available Formats</h4><ul><li>96-Well-Plate</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_96_well_plate_9a66005814.jpg" alt="Phenomenex: Strata X 96-well plate" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_96_well_plate_9a66005814.jpg 156w," sizes="100vw" width="1080" height="1080"><ul><li>1, 3, and 6mL Tubes</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_tubes_1_9b04cab6c1.jpg" alt="Phenomenex: Strata X 1, 3, and 6mL Tubes" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_tubes_1_9b04cab6c1.jpg 156w," sizes="100vw" width="1080" height="1080"><ul><li>Giga Tubes (12-150mL Tubes)</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_tubes_2_a8cd1706ec.jpg" alt="Phenomenex: Strata X Giga Tubes (12-150mL Tubes)" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_tubes_2_a8cd1706ec.jpg 156w," sizes="100vw" width="1080" height="1080">

Phenomenex Strata X Solid Phase Extraction (SPE)

Strata-X reversed phase SPE retains neutrals, acids, and bases via π-π, hydrogen bonding, and hydrophobic interactions. Robust cleanup under high organic wash.

Reversed Phase Solid Phase Extraction (SPE)A reversed phase functionalized polymeric sorbent that gives strong retention of neutral, acidic, or basic compounds under aggressive, high organic wash conditions. This sorbent relies on 3 mechanisms of retention: pi-pi bonding, hydrogen bonding (dipole-dipole interactions), and hydrophobic interaction.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_d8f4451e42.jpg" alt="Phenomenex: Strata-X" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_d8f4451e42.jpg 245w," sizes="100vw" width="433" height="247"><ul><li>Recommended Use: Extraction of neutrals and aromatics</li></ul><h4>Starting Method</h4><h5>For Neutral Compounds</h5><ul><li>Column: 1 mL Methanol</li><li>Equilibrate: 1 mL Water</li><li>Load: Diluted Sample</li><li>Wash: 1 mL 5-60 % Methanol</li><li>Elute: 2x 500 µL 2 % Formic Acid in Methanol/Acetonitrile</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_single_tube_435d45d0ad.jpg" alt="Phenomenex: Strata X single tube" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_single_tube_435d45d0ad.jpg 156w," sizes="100vw" width="1080" height="1080">Based on 30 mg/1 mL sorbent mass. The above is a convenient starting point for SPE method development, further optimization may be required to tailor the method for your specific extraction needs.<h4>Available Formats</h4><ul><li>96-Well-Plate</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_96_well_plate_9a66005814.jpg" alt="Phenomenex: Strata X 96-well plate" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_96_well_plate_9a66005814.jpg 156w," sizes="100vw" width="1080" height="1080"><ul><li>1, 3, and 6mL Tubes</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_tubes_1_9b04cab6c1.jpg" alt="Phenomenex: Strata X 1, 3, and 6mL Tubes" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_tubes_1_9b04cab6c1.jpg 156w," sizes="100vw" width="1080" height="1080"><ul><li>Giga Tubes (12-150mL Tubes)</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Strata_X_tubes_2_a8cd1706ec.jpg" alt="Phenomenex: Strata X Giga Tubes (12-150mL Tubes)" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Strata_X_tubes_2_a8cd1706ec.jpg 156w," sizes="100vw" width="1080" height="1080">

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

Products from category SPE sample preparation focused on Consumables - page 1

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