<p><strong>Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 18th August 2025? Check out new documents from the field of the gas phase, especially GC and GC/MS techniques!</strong></p><blockquote><p><span style="font-size:20px;">👉 </span><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library"><span style="font-size:20px;"><strong>SEARCH THE LARGEST REPOSITORY OF DOCUMENTS ABOUT GCMS AND RELATED TECHNIQUES</strong></span></a></p></blockquote><blockquote><p><strong>👉 Need info about different analytical techniques?</strong> Peek into <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library"><strong>LabRulezLCMS</strong></a> or <a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/library"><strong>LabRulezICPMS</strong></a> libraries.</p></blockquote><p>This week we bring you poster by <strong>Agilent Technologies / ASMS </strong>and application note<strong> </strong>by<strong> Shimadzu!</strong></p><h3><strong>1. Agilent Technologies / ASMS: New Pollutant Screening of Environmental Samples Using High-Resolution GC/Q-TOF and Accurate Mass Spectral Library of Emerging Environmental Pollutants&nbsp;</strong></h3><ul><li>Poster</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/ps_7250_pdcl_library_pal3_suremass_asms_2025_thp_083_en_agilent_3f1ac53d50.pdf"><strong>Full PDF for download</strong></a></li></ul><p>This paper conducts qualitative and semi - quantitative analysis of complex GC/Q-TOF sample data by using high-resolution, accurate-mass gas chromatography/quadrupole time-of-flight mass spectrometry (GC/Q-TOF), an accurate mass spectral library of environmental pollutants specifically created for emerging pollutant screening, and analytical software with a screening process platform. Actual environmental water samples are used to verify the sensitivity, accuracy, and spiked recovery rate of the solution. All results confirm that this solution is simple, stable, and effective, providing technical support for emerging pollutant screening.</p><h4><strong>Experimental</strong></h4><h5><strong>Instrument Analysis&nbsp;</strong></h5><p>The samples were analyzed by <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=8890+GC"><strong>Agilent 8890 GC</strong></a> and <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=7250+GC%2FQ-TOF"><strong>7250 high resolution accurate mass GC/Q-TOF system</strong></a>, It was configurated with a mid-column backflush setup (Figure 1). A 55.5 - min retention time locked GC oven temperature program is utilized which is listed in Table 1. The key mass spectrometry parameters of the GC/Q-TOF are as follows: It operates in the Electron Ionization (EI) mode with an energy of 70 electron volts, conducts detection in the time-of-flight scan mode within a mass-to-charge ratio range of 50 - 1000. The spectral acquisition rate is 5 Hz, and both the interface temperature and the source temperature are set at 280 °C. Data analysis is performed with the assistance of MassHunter data analysis software. The high-resolution accurate mass spectral library employed in the screening process is independently created by the laboratory.</p><h5><strong>Data Analysis&nbsp;</strong></h5><ul><li>The data processing used Agilent <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=Masshunter+software"><strong>Masshunter data analysis software</strong></a>, including Suremass.&nbsp;</li><li>The target screening of new pollutants was based on an independently created by the laboratory GC/Q-TOF PCDL library<sup>1</sup>.</li></ul><h4><strong>Conclusions&nbsp;</strong></h4><ul><li>Based on the currently collected list of new pollutants, a truly meaningful new pollutant PCDL high-resolution spectral library has been created.&nbsp;</li><li>This work demonstrated a total workflow for targeted screening and semi-quantification in real water sample.&nbsp;</li><li>The confidence in identification of new pollutants was enhanced by stable RT and excellent mass accuracy as a result of using an RTL backflush method and highresolution accurate mass measurement.</li></ul><h3><strong>2. Shimadzu: Analysis of SAF Using Comprehensive Two- Dimensional Gas Chromatography (GC× GC)&nbsp;</strong></h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/an_01_00862_en_f1ee0a435f.pdf"><strong>Full PDF for download</strong></a></li></ul><h4><strong>User Benefits</strong></h4><ul><li>By comparing chromatograms obtained as two-dimensional images, it can be utilized for quality control Inspection of SAF.</li><li>Changing the column combination customizes separation characteristics to the sample composition.</li><li>Utilizing the FASST (Fast Automated Scan/SIM Type) allows for the simultaneous analysis of the composition of SAF and the quantitative analysis of antioxidants.</li></ul><p>SAF (Sustainable Aviation Fuel) produced from waste cooking oil, used paper, and sugarcane has gained attention in recent years from the perspective of achieving a carbon neutral society. The physical properties of SAF,such as combustibility, vary depending on its components. Therefore, component analysis of SAF is crucial; however, since SAF is a mixture of various hydrocarbons, complete separation of each component is extremely challenging. Comprehensive two-dimensional gas chromatography (GC×GC), which utilizes the separation characteristics of two different types of columns, is an effective method for analyzing SAF with such a complex composition. Additionally, the GCMS-QP2050 enables ultra-fast scanning (30,000 u/sec), which improves the separation of adjacent peaks and allows for high-precision qualitative analysis(Application News No.01-00788-EN).</p><p>In this application, two types of SAF (A and B) and one intermediate product from the SAF production process (C) were measured using a combination of GC×GC with a non-polar column as the first column and a medium-polarity column as the second column. The two-dimensional images allow for a visual representation of the composition distribution, making quality control Inspection. Moreover, high separation of paraffins and naphthenes using a combination of a medium-polar column as the first column and a non-polar column asthe second column, as well as the quantification of antioxidants in SAF, which are regulated by concentration in ASTM D2425 will be introduced.</p><h5><strong>System Configuration</strong></h5><ul><li><strong>GC Model</strong>: <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=Nexis%E2%84%A2+GC-2030"><strong>Nexis GC-2030</strong></a> / <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=AOC-30i"><strong>AOC-30i</strong></a></li><li><strong>MS Model</strong>: <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=GCMS-QP2050"><strong>GCMS-QP2050</strong></a> (TMP exhaust: 255 L/sec)</li><li><strong>Injection Port</strong>: SPL</li><li><strong>Modulator: </strong>ZX1 thermal modulator (ZOEX corp.)</li><li><strong>Nitrogen generator: </strong>MT-24F (System Instruments Co., Ltd.)</li><li><strong>Software</strong>:<ul><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=Labsolutions+GCMS"><strong>Labsolutions<sup>TM</sup> GCMS</strong></a></li><li>GC Image (GC Image, LLC)</li></ul></li><li><strong>Library: </strong>NIST Mass Spectral Library</li></ul><h4><strong>Conclusion</strong></h4><p>Three SAF samples were measured using a combination of lowpolar to medium polar columns and compared the twodimensional images. The two-dimensional images allow for intuitive comprehension of the distribution of each component, making it easy to identify differences in composition and conducting quality control Inspection. Additionally, in the measurement of SAF using a combination of medium-polar to non-polar columns, the separation of paraffins and naphthenes was improved. Furthermore, by utilizing the FASST, composition analysis of SAF and quantitative analysis of antioxidants were simultaneously performed, which are regulated by concentration in ASTM D2425.</p>

News from LabRulezGCMS Library - Week 34, 2025

<p><strong>Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 5th January 2026? Check out new documents from the field of the gas phase, especially GC and GC/MS techniques!</strong></p><blockquote><p><span style="font-size:20px;">👉 </span><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library"><span style="font-size:20px;"><strong>SEARCH THE LARGEST REPOSITORY OF DOCUMENTS ABOUT GCMS AND RELATED TECHNIQUES</strong></span></a></p></blockquote><blockquote><p><strong>👉 Need info about different analytical techniques?</strong> Peek into <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library"><strong>LabRulezLCMS</strong></a> or <a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/library"><strong>LabRulezICPMS</strong></a> libraries.</p></blockquote><p>This week we bring you application notes by <strong>Agilent Technologies, EST Analytical </strong>and<strong> Shimadzu!</strong></p><h3><strong>1. Agilent Technologies: Ultrasensitive and Powerful GC/MS/MS for Analyzing Multipesticides in Black Pepper and Dried Tea</strong></h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/an_gcms_ms_black_pepper_5994_8783en_agilent_4b1cc85920.pdf"><strong>Full PDF for download</strong></a></li></ul><p>Pesticides play a vital role in safeguarding crops and are indispensable in most farming settings to secure high yields.1 Regulatory authorities, including the Codex Alimentarius and the European Commission mandate the monitoring and reporting of pesticide residues found in or on food product.2 The analysis of pesticides in food faces several major challenges, such as the variety of pesticide classes, the complexity of different food matrices, the effects of these matrices, and the detection of target analytes at low&nbsp;concentrations.3&nbsp;</p><p>According to the EU's SANTE/11312/2021 guidelines, black pepper and dried tea are considered among the difficult or unique commodity matrices for multiresidue pesticide analysis.4 The matrix interferences are complex and diverse, including carbohydrates, fats, piperine, terpenoids (for black pepper)5 , and caffeine (in dried tea). "For dried tea, matrix interferences include polyphenols, pigments, polysaccharides, alkaloids, free amino acids, high caffeine levels, and&nbsp;catechins".6&nbsp;</p><p>In addition to affecting the analyte signals, matrix interferences can cause the system to become contaminated more quickly. This leads to a rapid decline in the sensitivity of the analytical instrument, and necessitates frequent maintenance, significantly reducing laboratory productivity. These are the current challenges faced by laboratories when analyzing pesticides in difficult and complex matrices.&nbsp;</p><p>To overcome these challenges, Agilent offers a robust solution with its backflush and JetClean self-cleaning ion source technologies integrated into the high-sensitivity 7010B GC/TQ system. Backflush technology prevents high‑boiling contaminants from reaching the detector, reducing the need for frequent maintenance and extending column life.7 This ensures consistent performance and minimizes downtime, thereby enhancing laboratory productivity.&nbsp;</p><p>With JetClean technology, your lab can significantly increase instrument uptime, as fewer manual cleanings are needed, maximizing productivity. This technology helps maintain data quality by ensuring a clean ion source, which guarantees run-to-run reproducibility. Additionally, JetClean enhances operator convenience through automated cleaning, requiring virtually no user intervention.8 Combined with the ultrasensitivity of the 7010B GC/TQ system, these technologies provide precise and reliable analysis of pesticides in complex matrices such as black pepper and dried tea. Agilent’s comprehensive approach effectively mitigates matrix interferences, preserves instrument sensitivity, and significantly boosts overall efficiency in pesticide analysis.</p><p>This application note describes a detailed approach for the simultaneous quantification of 284 pesticides in black pepper and dried tea samples. Agilent's solution for complex matrices demonstrates the sensitivity of the 8890 GC/7010B GC/TQ and confirms its robustness when using backflush and JetClean techniques.&nbsp;</p><h4><strong>Experimental and chemicals</strong></h4><h5><strong>GC/TQ parameters&nbsp;</strong></h5><p>The <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=8890"><strong>8890 GC</strong></a>/<a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=7010B"><strong>7010B GC/TQ systems</strong></a> (Figure 1) were optimized for wide calibration range performance. Equipped with an Agilent <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=7693A"><strong>7693A automatic liquid sampler </strong></a>and a 150-position tray, the GC operated in temperature‑programmed splitless injection mode with a multimode inlet. Detailed instrument parameters can be found in Table 1. Data acquisition was in dynamic MRM (dMRM) mode, enabling analysis of 284 pesticides with 1233 MRM transitions and up to 74 concurrent MRMs (see Figure 2). Retention time was synchronized with the Agilent Pesticides and Environmental Pollutants (P&amp;EP) 4.0 MRM Database, streamlining method&nbsp;setup.</p><h4><strong>Conclusion&nbsp;</strong></h4><p>This application note describes an approach for the analysis of multipesticides in complex and distinctive matrices, including black pepper and dried tea using the Agilent 8890 GC/7010B GC/TQ. The comprehensive solution successfully addresses the challenges encountered when analyzing multipesticides in difficult matrices such as black pepper and dried tea. The high sensitivity of the 7010B GC/TQ enables the application of deep dilution methods. Additionally, the use of backflush technology combined with the Agilent JetClean self-cleaning ion source ensures system stability and robustness, enhancing the operational efficiency of testing laboratories and reducing equipment downtime during&nbsp;maintenance.</p><h3><strong>2. EST Analytical: Static Headspace Sampling of Volatile Organic Compounds</strong></h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/Flex_8260_by_Static_Headspace_7ddf2e4157.pdf"><strong>Full PDF for download</strong></a></li></ul><h4><strong>Discussion</strong></h4><p>Purge and trap sampling involves purging the VOCs out of the matrix and trapping the analytes onto an analytical trap, the trap is then desorbed to the GC/MS. This process has a number of pros and cons. On the positive side, purge and trap is more sensitive. It is also the recommended sampling technique for USEPA Methods. Furthermore, the advent of autosampling systems has simplified sample preparation. However, purge and trap does have some negatives, including active sites, worries about foaming samples, and trap degradation.</p><p>Static headspace sampling, on the other hand, is much simpler than purge and trap sampling. For this sampling technique, the sample is brought to equilibrium and a portion of the headspace is transferred to the GC/MS for separation and analysis. The simplicity of this technique is a definite pro. Moreover, this sampling process does not develop active sites, has no need for an analytical trap and the linear calibration range can be much higher than that of purge and trap sampling. Conversely, samples need to be manually prepped thus, losing their sample integrity. Additionally, the detection limits are higher for a number of compounds. Finally, some of the analytes do not partition into the headspace well enough and need method optimization.&nbsp;</p><p>In recent years, GC/MS systems have become much more sensitive. The advent of SIM/Scan acquisition techniques has made low level detection a much simpler proposition. This analysis will focus on the headspace sampling and analysis of over 50 volatile organic compounds.&nbsp;</p><h4><strong>Experimental</strong></h4><p>The sampling system used for this analysis was the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2162"><strong>EST Analytical FLEX autosampler</strong></a> fitted with a 2.5ml headspace syringe. An <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=7890+GC"><strong>Agilent 7890 GC</strong></a> and <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=5975"><strong>5975 MS</strong></a> were used for separation and analysis. The GC was configured with a Restek Rxi 624 Sil MS 30m x 250mm x 1.4µm column and a SKY 2mm x 6.5 x 78.5 splitless inlet liner. The MS was run in SIM/Scan mode. Refer to Tables 1 and 2 for the analysis and sampling parameters.</p><h4><strong>Conclusions</strong></h4><p>Static headspace sampling in conjunction with SIM/Scan acquisition proved to be a good alternative to purge and trap sampling for a number of USEPA Method 8260 compounds. The curve %RSD results showed the linearity of the curve to meet the USEPA Method 8260 requirement of 15% or better. The method detection limits of all the compounds tested also passed method requirements. Lastly, the precision and accuracy of the autosampling and analysis system was excellent, with the average precision at less than 6% RSD and the average %recovery at just over 101%.</p><h3><strong>3. Shimadzu: Aromatic Component Analysis of Gasoline According to ASTM D5580 Using the Brevis GC- 2050 Gas Chromatograph</strong></h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/an_01_01024_en_039b304288.pdf"><strong>Full PDF for download</strong></a></li></ul><p>Aromatics, such as toluene and xylene, are sometimes added to gasoline to improve the octane number. Measuring the levels of these aromatics is essential for quality control in gasoline production. It is also important for environmental protection, in particular, for reducing emissions of benzene, a hazardous substance, as well as for sustainable energy use that reduces the environmental impact of gasoline while maintaining its performance.</p><p>ASTM D55801) is a standard test method that uses gas chromatography to measure aromatics in gasoline. Gasoline aromatics can be separated more effectively by switching between two gas chromatography columns of different polarities and venting non-aromatic components from the system. This Application News describes using the Brevis GC2050 gas chromatograph to determine aromatics in gasoline by applying ASTM D5580.</p><h4><strong>Equipment Configuration and Analytical Conditions&nbsp;</strong></h4><p>The system comprises a <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=Brevis+GC-2050"><strong>Brevis GC-2050 gas chromatograph</strong></a>, an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=AOC-30"><strong>AOC-30</strong></a> for sample injection, and a VB-30-S heated valve box. Aromatics were determined using two sets of Analysis Conditions that were tailored to measure different components (Table 1). Note that the timing of the flow path switching and other conditions needs to be adjusted according to the columns being used and the operating environment.</p><h4><strong>Determining Aromatics in Gasoline&nbsp;</strong></h4><p>A gasoline sample was prepared by adding 2 to 10 wt% aromatics and 10 wt% of an internal standard (2-hexanone) and then analyzed under Analysis Conditions A and Analysis Conditions B. Fig. 2 shows the chromatograms obtained under each set of Analysis Conditions. Despite gasoline containing large amounts of hydrocarbons, oxygenates, and other impurities, these impurities did not appear as peaks in the chromatograms, and only the aromatics added to the gasoline were detected. These results verify the utility of using flow path switching to effectively utilize the characteristics of two different columns.</p><h4><strong>Conclusion&nbsp;</strong></h4><p>A flow path switching valve was installed on a Brevis GC-2050 gas chromatograph to enable the determination of gasoline aromatics (benzene, toluene, ethylbenzene, p/m-xylene, oxylene, and C9+ aromatics) according to ASTM D5580.&nbsp;</p><p>This system can switch between different columns during analysis to determine specific aromatics from among the many compounds present in gasoline. Analysis was performed under two sets of conditions, each using different flow path switching times. This method met the requirements for linearity and reproducibility described in ASTM D5580. The timing of flow path switching can also be adjusted to allow the targeted determination of oxygenates in gasoline. The ability to perform multiple analyses on a single system means the Brevis GC-2050 offers even greater functionality as a compact gas chromatograph.</p>

News from LabRulezGCMS Library - Week 02, 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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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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