We would like to thank EAN University and the University of La Laguna.

1. Preparation of the stock and working solutions
NOTE: For safety reasons, it is advisable to wear nitrile gloves, a laboratory coat, and safety glasses throughout the protocol.
<ol>
	<li>Prepare individual stock solutions of each of the 45 commercial pesticide standards (see Table of Materials) at approximately 1,000 mg/L in acetonitrile in 10 mL volumetric flasks.</li>
	<li>Combine the above individual stock solutions to prepare a 400 mg/L stock solution in acetonitrile in a 25 mL volumetric flask. 
	NOTE: This mixed solution will be utilized to prepare the working solutions for recovery and calibration experiments.</li>
	<li>Prepare stock solutions of atrazine-d5 and triphenyl phosphate (TPP) at concentrations of 750 mg/L and 1,050 mg/L, respectively, in acetonitrile in 10 mL volumetric flasks. Utilize atrazine-d5 as a procedural internal standard (P-IS) and TPP as an injection internal standard (I-IS). 
	NOTE: The ideal scenario would involve the utilization of an isotopically labeled internal standard for each specific target analyte.</li>
	<li>Prepare stock recovery solutions in acetonitrile containing 0.05% (v/v) of formic acid (to prevent degradation) in 10 mL volumetric flasks to yield 10, 100, and 400 &#181;g/kg sample equivalents for the pesticides and 200 &#181;g/kg for the P-IS separately. Store these solutions in amber glass vials in the dark at &#8722;20 &#176;C.</li>
	<li>Prepare calibration solutions of the pesticides and P-IS together in acetonitrile with 0.05% (v/v) of formic acid in 10 mL volumetric flasks to yield 5, 10, 25, 75, 200, 400, and 600 &#181;g/kg, and 200 ng/ng, respectively, and store them in amber glass vials in the darkness at &#8722;20 &#176;C. 
	NOTE: The same solutions may be utilized throughout the experimental work but storing them under the specified conditions immediately after each use is essential.</li>
	<li>Prepare a mixture of analyte protectants containing 100 g/L of 3-ethoxy-1,2-propanediol, 10 g/L of L-gulonic acid &#947;-lactone, 10 g/L of D-sorbitol, and 5 g/L of shikimic acid in a 4/1 (v/v) ratio of acetonitrile to water with 0.5% (v/v) of formic acid. 
	NOTE: This mixture of analyte protectants is to be added just before the injection to mitigate ME.</li>
</ol>
2. Sample collection
<ol>
	<li>Collect samples from three avocado species (e.g., Criollo, Hass, and Lorena) available at supermarkets. Ensure that each sample weighs approximately 1 kg, which is enough for conducting all the subsequent studies and aligns with Directive 2002/63/CE21. 
	NOTE: Organic samples were preferentially selected to minimize the likelihood of the presence of pesticide residues.</li>
	<li>Transport the collected avocado samples to the laboratory, and individually homogenize them without the pipe using a chopper (see Table of Materials). Store the homogenized samples in amber glass containers at 4 &#176;C until analysis. 
	NOTE: The same avocado samples will be used throughout the entire study. Therefore, it is crucial to store them under the specified conditions immediately after each use.</li>
</ol>
3. Sample preparation utilizing the QuEChERS method with ammonium formate
NOTE: Figure 1 illustrates a schematic representation of the QuEChERS method with ammonium formate.
<ol>
	<li>Weigh 5 g of each avocado sample in a 50 mL centrifuge tube (see Table of Materials).</li>
	<li>Add 50 &#181;L of the P-IS solution to yield a concentration of 200 &#181;g/kg. For recovery assessment, also add the pesticide solutions prepared in step 1.4 to yield concentrations of 10, 100, and 400 &#181;g/kg (n = 5 each).</li>
	<li>Vortex the tube for 30 s to ensure thorough integration of the spike into the sample.</li>
	<li>Add 10 mL of acetonitrile to the centrifuge tube. Shake the tube at 70 rpm for 5 min.</li>
	<li>Add 2.5 g of ammonium formate, shake the tube again at 70 rpm for 5 min, and subsequently centrifuge it at 1,800 &#215; g for 5 min.</li>
	<li>To a 2 mL centrifuge tube containing 150 mg of anhydrous MgSO4, 50 mg of primary-secondary amine (PSA), 50 mg of octadecylsilane (C18), 10 mg of graphitized carbon black (GCB), and 60 mg of a zirconium oxide-based sorbent Z-Sep+, add 1 mL of the extract for purification utilizing dispersive-solid phase extraction (d-SPE). Vortex the tube for 30 s and centrifuge it at 1,800 &#215; g for 5 min.</li>
	<li>Transfer 200 &#181;L of the extract to an autosampler vial, add 20 &#181;L of the analyte protectant solution prepared in step 1.6, and include 50 &#181;L of the TPP solution.</li>
	<li>Perform instrumental analysis using a GC-MS/MS system (see section 4).</li>
	<li>Perform matrix-matched calibration following the same procedure as described above, using blank extracts, except, during the d-SPE step (step 3.6), clean 5 mL of the supernatant in 15 mL tubes. Add the spike and P-IS solutions at step 3.7. Add the calibration standard solutions to the autosampler vials to yield 5, 10, 25, 50, 100, 200, 400, and 600 &#181;g/kg, along with the TPP, resulting in a final volume of 270 &#181;L. 
	NOTE: Overall, be sure to construct matrix-matched calibration curves for each avocado variety plus the acetonitrile-only calibrations.</li>
</ol>
4. Instrumental analysis using GC-MS/MS
<ol>
	<li>Conduct the analyses employing a GC-MS/MS system with a triple quadrupole (TQ) equipped with an electron ionization interface (&#8722;70 eV) and an autosampler (see Table of Materials).</li>
	<li>Employ an MS GC column (silica Bond of 30 m length, 0.25 mm inner diameter, 0.25 &#181;m film thickness) along with ultrahigh purity Helium as the carrier gas at a constant flow rate of 1.2 mL/min.</li>
	<li>Verify the following parameters before proceeding with the equipment operation:
	<ol>
		<li>Ensure that the gas pressures are correct: Helium at 140 psi and Argon at 65 psi.</li>
		<li>Check the condition of the rotary pump oil to ensure that it is clear and at the appropriate level.</li>
		<li>Ensure that the injection syringe does not have any obstructions from previous injections.</li>
		<li>Confirm that the wash vials contain a sufficient volume of each solvent.</li>
		<li>Check that the consumables counter (septum, liner) has not reached its limit.</li>
	</ol>
	</li>
	<li>Turn on the main GC switch located on the front panel and turn on the MS switch located at the back.</li>
	<li>Open the GCMS Real Time Analysis software that controls all the parameters of the GC-MS/MS system. 
	NOTE: The instrument system includes the GCMS Real Time Analysis software by default.</li>
	<li>Click on Vacuum Control | Advanced | Rotary Pump 1 to initiate the vacuum system. 
	NOTE: In this window, monitor the pressure to determine the optimal vacuum values, which should be lower than 9.0 Pa. It will take approximately 12 h.</li>
	<li>Click on Start to turn on turbo molecular pump 1 and turbo molecular pump 2.</li>
	<li>Click on Start for the Ion Source Heater option. 
	NOTE: After a recommended time of 1 h, check the system&#39;s vacuum to confirm that the recommended value is lower than 1.6e-3 Pa.</li>
	<li>Set the MS interface temperature to 250 &#176;C and the ion source temperature to 300 &#176;C.</li>
	<li>Maintain the GC oven at an initial temperature of 50 &#176;C for 1 min, then ramp it up to 180 &#176;C at a rate of 25 &#176;C/min. Subsequently, increase the temperature to 230 &#176;C at 5 &#176;C/min and then to 290 &#176;C at 25 &#176;C/min. Finally, keep the temperature constant at 290 &#176;C for 6 min. The total analysis time is 24.6 min.</li>
	<li>Click on Close once all these systems are turned on.</li>
	<li>Click on the Tuning option from the analysis software and click on Peak Monitor View to perform an initial verification of the mass spectrometer conditions. 
	&#8203;NOTE: If necessary, perform autotuning.</li>
	<li>Click on Acquisition, and from the displayed window, click on Download Initial Parameters. Verify that the equipment is ready GC and ready MS.</li>
</ol>
5. Data acquisition
<ol>
	<li>Click on New Batch File from the software and create a sequence containing information such as sample name, sample ID, method file, data file, injection volume, and tuning file. Add rows as necessary and click on Save.</li>
	<li>Click on Batch Start and let the injection process commence.</li>
	<li>Perform the injection at 250 &#176;C in the splitless mode, maintaining an injection volume of 1 &#181;L. After 1 min following the injection, open the split. 
	NOTE: Between injections, be sure to clean the 10 &#181;L syringe with methanol, ethyl acetate, and acetonitrile, using a single rinse with each solvent. All the injections are performed in triplicate.</li>
	<li>Analyze the analytes using the multiple reaction monitoring (MRM) mode, which is the standard mode employed in MS/MS systems with a TQ. 
	NOTE: Table 1 provides the retention times (in min) and the quantifier and qualifier transitions for the multiclass pesticides, P-IS, and I-IS. The quantitative analysis relies on the ratio of the peak area of the quantitation ion to the P-IS ion. The I-IS is employed for quality control during injection. Supplementary File 1 contains chromatograms for all the 45 analyzed pesticides.</li>
	<li>Open the Postrun Analysis software for data analysis. 
	NOTE: The instrument system includes the GCMS Postrun Analysis software by default.</li>
	<li>Click on the injection to be analyzed, navigate through the table containing the analytes, and select the peak of interest.</li>
	<li>Click on the peak or the region of interest to visualize the chromatogram. Review the peak integrations, and if necessary, perform manual integration. Verify the areas of all analytes to perform the necessary calculations and method evaluation.</li>
</ol>

Analyzing Pesticides in Avocado Using the QuEChERS Method and CG-MS/MS

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A., Gonz&#225;lez-Curbelo, M. &. #. 1. 9. 3. ;., Gonz&#225;lez-S&#225;lamo, J., Hern&#225;ndez-Borges, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-throughput+analysis+of+pesticides+in+minor+tropical+fruits+from+Colombia.">High-throughput analysis of pesticides in minor tropical fruits from Colombia.</a> Food Chem. 280, 221-230 (2019).</li><li>Li, L., Li, W., Qin, D. M., Jiang, S. R., Liu, F. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+graphitized+carbon+black+to+the+QuEChERS+method+for+pesticide+multiresidue+analysis+in+spinach.">Application of graphitized carbon black to the QuEChERS method for pesticide multiresidue analysis in spinach.</a> J AOAC Int. 92 (2), 538-547 (2009).</li></ol>

The authors have no conflicts of interest to disclose.

The primary limitation associated with matrix-matched calibration arises from the use of blank samples as calibration standards. This leads to an augmented number of samples to be processed for analysis and an increased injection of matrix components in each analytical sequence, potentially leading to higher instrument maintenance demands. Nonetheless, this strategy is more suitable than standard addition, which would generate a much larger number of samples to be injected due to the need to perform a calibration curve f...

In chemical analysis, the matrix effect (ME) can be defined in various ways, but a widely accepted general definition is as follows: it refers to the change in the signal, particularly a change in the slope of the calibration curve when the sample matrix or portion of it is present during the analysis of a specific analyte. As a critical aspect, ME necessitates thorough investigation during the validation process of any analytical method, as it directly affects the accuracy of quantitative measurement for the target analytes1. Ideally, a sample pretreatment procedure should be selective enough to avoid extracting any components from the sample matrix. However, despite significant efforts, many of these matrix components still end up in the final determination systems in most cases. Consequently, such matrix components often compromise the recovery and precision values, introduce additional noise, and escalate the overall cost and labor involved in the method.
In gas chromatography (GC), ME arises due to the presence of active sites within the GC system, which interact with the target analytes through various mechanisms. On the one hand, the matrix constituents block or mask these active sites that would otherwise interact with the target analytes, resulting in frequent signal enhancement2. On the other hand, active sites that remain unobstructed may cause peak tailing or analyte decomposition due to strong interactions, leading to a negative ME. However, this can offer potential benefits in certain cases2. It is crucial to emphasize that achieving complete inertness in a GC system is exceedingly challenging, despite using highly inert components and proper maintenance. With continuous use, the accumulation of matrix components in the GC system becomes more pronounced, causing an increased ME. Nowadays, it is widely recognized that analytes containing oxygen, nitrogen, phosphorus, sulfur, and similar elements, exhibit a greater ME as they readily interact with these active sites. Conversely, highly stable compounds such as hydrocarbons or organohalogens do not undergo such interactions and do not show observable ME during analysis2,3.
Overall, ME cannot be fully eliminated, leading to the development of several strategies for compensation or correction when complete removal of matrix components is not feasible. Among these strategies, the utilization of deuterated internal standards (ISs), analyte protectants, matrix-matched calibration, the standard addition method, or the modification of injection techniques have been documented in scientific literature1,2,4,5. The SANTE/11312/2021 guidelines have also recommended these strategies6.
Regarding the application of matrix-matched calibration to compensate for MEs, sample sequences in practical situations encompass diverse types of foods or various samples from the same commodity. In this case, the assumption is made that employing any sample from the same commodity will effectively compensate for ME in all samples. However, there is a lack of sufficient studies in the existing literature that specifically investigate this issue7.
The multiresidue determination of pesticides in matrices containing an appreciable percentage of fat and pigments constitutes a challenging task. The considerable amount of coextracted material can significantly affect the extraction efficiency and interfere with the subsequent chromatographic determination, potentially damaging the column, source, and detector, and resulting in significant MEs8,9,10. Consequently, the analysis of pesticides at trace levels in such matrices necessitates a significant reduction of matrix components before analysis while ensuring high recovery values7. Obtaining high recovery values is crucial to ensure that pesticide analyses remain reliable, accurate, and compliant with regulatory standards. This is vital for ensuring food safety, environmental protection, and informed decision-making in agriculture and related fields.
Avocado is a fruit of high commercial value cultivated in tropical and Mediterranean climates worldwide and widely consumed both in its regions of origin and in the numerous export markets. From the analytical point of view, avocado is a complex matrix containing a significant number of fatty acids (i.e., oleic, palmitic, and linoleic), similar to nuts, a significant pigment content, as in green leaves, as well as sugars and organic acids, similar to those found in other fruits11. Due to its fatty nature, special attention must be given when employing any analytical method for analysis. While pesticide residue analysis has been conducted on avocados using GC-MS in some instances8,12,13,14,15,16,17,18,19,20, it has been relatively less frequent compared to other matrices. In most cases, a version of the Quick-Easy-Cheap-Effective-Rugged-Safe (QuEChERS) method has been applied8,12,13,14,15,16,17,18. None of these studies have investigated the consistency of MEs among different avocado varieties.
Therefore, the aim of this work was to study the consistency of MEs and recovery values for 45 representative pesticides across different varieties of avocado (i.e., Criollo, Hass, and Lorena) using the QuEChERS method with ammonium formate and GC-MS/MS. To the best of our knowledge, this is the first time that this type of study has been conducted on such fatty matrix samples.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>3-Ethoxy-1,2-propanediol</td>
			<td>Sigma Aldrich</td>
			<td>260428-1G</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetonitrile</td>
			<td>Merk</td>
			<td>1006652500</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium formate</td>
			<td>Sigma Aldrich</td>
			<td>156264-1KG</td>
			<td></td>
		</tr>
		<tr>
			<td>AOAC 20i/s autosampler</td>
			<td>Shimadzu</td>
			<td>221-723115-58</td>
			<td></td>
		</tr>
		<tr>
			<td>Automatic shaker MX-T6-PRO</td>
			<td>SCILOGEX</td>
			<td>8.23222E+11</td>
			<td></td>
		</tr>
		<tr>
			<td>Balance</td>
			<td>OHAUS</td>
			<td>PA224</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge tubes, 15 mL</td>
			<td>Nest</td>
			<td>601002</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge tubes, 2 mL</td>
			<td>Eppendorf</td>
			<td>4610-1815</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge tubes, 50 mL</td>
			<td>Nest</td>
			<td>602002</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge Z206A</td>
			<td>MERMLE</td>
			<td>6019500118</td>
			<td></td>
		</tr>
		<tr>
			<td>Choper 2L</td>
			<td>Oster</td>
			<td>2114111</td>
			<td></td>
		</tr>
		<tr>
			<td>Column SH-Rxi-5sil MS, 30 m x 0.25 mm, 0.25 &#181;m</td>
			<td>Shimadzu</td>
			<td>221-75954-30</td>
			<td>MS GC column&#160;</td>
		</tr>
		<tr>
			<td>Dispensette 5-50 mL</td>
			<td>BRAND</td>
			<td>4600361</td>
			<td></td>
		</tr>
		<tr>
			<td>DSC-18</td>
			<td>Sigma Aldrich</td>
			<td>52600-U</td>
			<td></td>
		</tr>
		<tr>
			<td>D-Sorbitol</td>
			<td>Sigma Aldrich</td>
			<td>240850-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethyl acetate</td>
			<td>Merk</td>
			<td>1313181212</td>
			<td></td>
		</tr>
		<tr>
			<td>GCMS-TQ8040&#160;</td>
			<td>Shimadzu</td>
			<td>211552</td>
			<td></td>
		</tr>
		<tr>
			<td>Graphitized carbon black</td>
			<td>Sigma Aldrich</td>
			<td>57210-U</td>
			<td></td>
		</tr>
		<tr>
			<td>Injection syringe</td>
			<td>Shimadzu</td>
			<td>LC2213461800</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Gulonic acid &#947;-lactone</td>
			<td>Sigma Aldrich</td>
			<td>310301-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>Linner splitless</td>
			<td>Shimadzu</td>
			<td>221-4887-02</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium sulfate anhydrus</td>
			<td>Sigma Aldrich</td>
			<td>M7506-2KG</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Panreac</td>
			<td>131091.12.12</td>
			<td></td>
		</tr>
		<tr>
			<td>Milli-Q ultrapure (type 1) water</td>
			<td>Millipore</td>
			<td>F4H4783518</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette tips 10 - 100 &#181;L</td>
			<td>Biologix</td>
			<td>200010</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette tips 100 - 1000 &#181;L</td>
			<td>Brand</td>
			<td>541287</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette tips 20 - 200 &#181;L</td>
			<td>Brand</td>
			<td>732028</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipettes Pasteur</td>
			<td>NORMAX</td>
			<td>5426023</td>
			<td></td>
		</tr>
		<tr>
			<td>Pippette Transferpette S variabel 10 - 100 &#181;L</td>
			<td>BRAND</td>
			<td>704774</td>
			<td></td>
		</tr>
		<tr>
			<td>Pippette Transferpette S variabel 100 - 1000 &#181;L</td>
			<td>BRAND</td>
			<td>704780</td>
			<td></td>
		</tr>
		<tr>
			<td>Pippette Transferpette S variabel 20 - 200 &#181;L</td>
			<td>SCILOGEX</td>
			<td>7.12111E+11</td>
			<td></td>
		</tr>
		<tr>
			<td>Primary-secondary amine</td>
			<td>Sigma Aldrich</td>
			<td>52738-U</td>
			<td></td>
		</tr>
		<tr>
			<td>Shikimic acid</td>
			<td>Sigma Aldrich</td>
			<td>S5375-1G</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe Filter PTFE/L 25 mm, 0.45 &#181;m</td>
			<td>NORMAX</td>
			<td>FE2545I</td>
			<td></td>
		</tr>
		<tr>
			<td>Triphenyl phosphate (QC)</td>
			<td>Sigma Aldrich</td>
			<td>241288-50G</td>
			<td></td>
		</tr>
		<tr>
			<td>Vials with fused-in insert</td>
			<td>Sigma Aldrich</td>
			<td>29398-U</td>
			<td></td>
		</tr>
		<tr>
			<td>Z-SEP+</td>
			<td>Sigma Aldrich</td>
			<td>55299-U</td>
			<td>zirconium oxide-based sorbent</td>
		</tr>
		<tr>
			<td>Pesticides</td>
			<td></td>
			<td></td>
			<td>CAS registry number</td>
		</tr>
		<tr>
			<td>4,4&#180;-DDD</td>
			<td>Sigma Aldrich</td>
			<td>35486-250MG</td>
			<td>72-54-8</td>
		</tr>
		<tr>
			<td>4,4&#180;-DDE</td>
			<td>Sigma Aldrich</td>
			<td>35487-100MG</td>
			<td>72-55-9</td>
		</tr>
		<tr>
			<td>4,4&#180;-DDT</td>
			<td>Sigma Aldrich</td>
			<td>31041-100MG</td>
			<td>50-29-3</td>
		</tr>
		<tr>
			<td>Alachlor</td>
			<td>Sigma Aldrich</td>
			<td>45316-250MG</td>
			<td>15972-60-8</td>
		</tr>
		<tr>
			<td>Aldrin</td>
			<td>Sigma Aldrich</td>
			<td>36666-25MG</td>
			<td>309-00-2</td>
		</tr>
		<tr>
			<td>Atrazine</td>
			<td>Sigma Aldrich</td>
			<td>45330-250MG-R</td>
			<td>1912-24-9</td>
		</tr>
		<tr>
			<td>Atrazine-d5 (IS)</td>
			<td>Sigma Aldrich</td>
			<td>34053-10MG-R</td>
			<td>163165-75-1</td>
		</tr>
		<tr>
			<td>Buprofezin</td>
			<td>Sigma Aldrich</td>
			<td>37886-100MG</td>
			<td>69327-76-0</td>
		</tr>
		<tr>
			<td>Carbofuran</td>
			<td>Sigma Aldrich</td>
			<td>32056-250-MG</td>
			<td>1563-66-2</td>
		</tr>
		<tr>
			<td>Chlorpropham</td>
			<td>Sigma Aldrich</td>
			<td>45393-250MG</td>
			<td>101-21-3</td>
		</tr>
		<tr>
			<td>Chlorpyrifos</td>
			<td>Sigma Aldrich</td>
			<td>45395-100MG</td>
			<td>2921-88-2</td>
		</tr>
		<tr>
			<td>Chlorpyrifos-methyl</td>
			<td>Sigma Aldrich</td>
			<td>45396-250MG</td>
			<td>5598-13-0</td>
		</tr>
		<tr>
			<td>Deltamethrin</td>
			<td>Sigma Aldrich</td>
			<td>45423-250MG</td>
			<td>52918-63-5</td>
		</tr>
		<tr>
			<td>Dichloran</td>
			<td>Sigma Aldrich</td>
			<td>45435-250MG</td>
			<td>99-30-9</td>
		</tr>
		<tr>
			<td>Dichlorvos</td>
			<td>Sigma Aldrich</td>
			<td>45441-250MG</td>
			<td>62-73-7</td>
		</tr>
		<tr>
			<td>Dieldrin</td>
			<td>Sigma Aldrich</td>
			<td>33491-100MG-R</td>
			<td>60-57-1</td>
		</tr>
		<tr>
			<td>Diphenylamine</td>
			<td>Sigma Aldrich</td>
			<td>45456-250MG</td>
			<td>122-39--4</td>
		</tr>
		<tr>
			<td>Endosulfan A</td>
			<td>Sigma Aldrich</td>
			<td>32015-250MG</td>
			<td>115-29-7</td>
		</tr>
		<tr>
			<td>Endrin</td>
			<td>Sigma Aldrich</td>
			<td>32014-250MG</td>
			<td>72-20-8</td>
		</tr>
		<tr>
			<td>EPN</td>
			<td>Sigma Aldrich</td>
			<td>36503-100MG</td>
			<td>2104-64-5</td>
		</tr>
		<tr>
			<td>Esfenvalerate</td>
			<td>Sigma Aldrich</td>
			<td>46277-100MG</td>
			<td>66230-04-4</td>
		</tr>
		<tr>
			<td>Ethion</td>
			<td>Sigma Aldrich</td>
			<td>45477-250MG</td>
			<td>563-12-2</td>
		</tr>
		<tr>
			<td>Fenamiphos</td>
			<td>Sigma Aldrich</td>
			<td>45483-250MG</td>
			<td>22224-92-6</td>
		</tr>
		<tr>
			<td>Fenitrothion</td>
			<td>Sigma Aldrich</td>
			<td>45487-250MG</td>
			<td>122-14-5</td>
		</tr>
		<tr>
			<td>Fenthion</td>
			<td>Sigma Aldrich</td>
			<td>36552-250MG</td>
			<td>55-38-9</td>
		</tr>
		<tr>
			<td>Fenvalerate</td>
			<td>Sigma Aldrich</td>
			<td>45495-250MG</td>
			<td>51630-58-1</td>
		</tr>
		<tr>
			<td>HCB</td>
			<td>Sigma Aldrich</td>
			<td>45522-250MG</td>
			<td>118-74-1</td>
		</tr>
		<tr>
			<td>Iprodione</td>
			<td>Sigma Aldrich</td>
			<td>36132-100MG</td>
			<td>36734-19-7</td>
		</tr>
		<tr>
			<td>Lindane</td>
			<td>Sigma Aldrich</td>
			<td>45548-250MG</td>
			<td>58-89-9</td>
		</tr>
		<tr>
			<td>Malathion</td>
			<td>Sigma Aldrich</td>
			<td>36143-100MG</td>
			<td>121-75-5</td>
		</tr>
		<tr>
			<td>Metalaxyl</td>
			<td>Sigma Aldrich</td>
			<td>32012-100MG</td>
			<td>57837-19-1</td>
		</tr>
		<tr>
			<td>Methidathion</td>
			<td>Sigma Aldrich</td>
			<td>36158-100MG</td>
			<td>950-37-8</td>
		</tr>
		<tr>
			<td>Myclobutanil</td>
			<td>Sigma Aldrich</td>
			<td>34360-100MG</td>
			<td>88671-89-0</td>
		</tr>
		<tr>
			<td>Oxyfluorfen</td>
			<td>Sigma Aldrich</td>
			<td>35031-100MG</td>
			<td>42874-03-3</td>
		</tr>
		<tr>
			<td>Parathion-methyl</td>
			<td>Sigma Aldrich</td>
			<td>36187-100MG</td>
			<td>298-00-0</td>
		</tr>
		<tr>
			<td>Penconazol</td>
			<td>Sigma Aldrich</td>
			<td>36189-100MG</td>
			<td>66246-88-6</td>
		</tr>
		<tr>
			<td>Pirimiphos-methyl</td>
			<td>Sigma Aldrich</td>
			<td>32058-250MG</td>
			<td>29232-93-7</td>
		</tr>
		<tr>
			<td>Propiconazole</td>
			<td>Sigma Aldrich</td>
			<td>45642-250MG</td>
			<td>60207-90-1</td>
		</tr>
		<tr>
			<td>Propoxur</td>
			<td>Sigma Aldrich</td>
			<td>45644-250MG</td>
			<td>114-26-1</td>
		</tr>
		<tr>
			<td>Propyzamide</td>
			<td>Sigma Aldrich</td>
			<td>45645-250MG</td>
			<td>23850-58-5</td>
		</tr>
		<tr>
			<td>Pyriproxifen</td>
			<td>Sigma Aldrich</td>
			<td>34174-100MG</td>
			<td>95737-68-1</td>
		</tr>
		<tr>
			<td>Tolclofos-methyl</td>
			<td>Sigma Aldrich</td>
			<td>31209-250MG</td>
			<td>5701804-9</td>
		</tr>
		<tr>
			<td>Triadimefon</td>
			<td>Sigma Aldrich</td>
			<td>45693-250MG</td>
			<td>43121-43-3</td>
		</tr>
		<tr>
			<td>Triflumizole</td>
			<td>Sigma Aldrich</td>
			<td>32611-100MG</td>
			<td>68694-11-1</td>
		</tr>
		<tr>
			<td>&#945;-HCH</td>
			<td>Sigma Aldrich</td>
			<td>33377-50MG</td>
			<td>319-86-8</td>
		</tr>
		<tr>
			<td>&#946;-HCH</td>
			<td>Sigma Aldrich</td>
			<td>33376-100MG</td>
			<td>319-85-7</td>
		</tr>
	</tbody>
</table>

determination of 45 pesticides in avocado varieties by the quechers method and gas chromatography-tandem mass spectrometry

Gas chromatography (GC) tandem mass spectrometry (MS/MS) stands as a preeminent analytical instrument extensively employed for the surveillance of pesticide residues in food. Nevertheless, these methods are vulnerable to matrix effects (MEs), which can potentially affect accurate quantification depending on the specific combination of analyte and matrix. Among the various strategies to mitigate MEs, matrix-matched calibration represents the prevailing approach in pesticide residue applications due to its cost-effectiveness and straightforward implementation. In this study, a total of 45 representative pesticides were analyzed in three different varieties of avocado (i.e., Criollo, Hass, and Lorena) using the Quick-Easy-Cheap-Effective-Rugged-Safe (QuEChERS) method with ammonium formate and GC-MS/MS. 
For this purpose, 5 g of the avocado sample was extracted with 10 mL of acetonitrile, and then 2.5 g of ammonium formate was added to induce phase separation. Subsequently, the supernatant underwent a cleanup process via dispersive solid-phase extraction employing 150 mg of anhydrous MgSO4, 50 mg of primary-secondary amine, 50 mg of octadecylsilane, 10 mg of graphitized carbon black, and 60 mg of a zirconium oxide-based sorbent (Z-Sep+). The GC-MS/MS analysis was successfully performed in less than 25 min. Rigorous validation experiments were carried out to assess the performance of the method. The examination of a matrix-matched calibration curve for each variety of avocado revealed that the ME remained relatively consistent and less than 20% (considered as a soft ME) for most pesticide/variety combinations. Furthermore, the method&#180;s limits of quantification were lower than 5 &#181;g/kg for all three varieties. Finally, the recovery values for most pesticides fell within the acceptable range of 70-120%, with relative standard deviation values below 20%.

Avocado Sample Preparation Using the QuEChERS Method with Ammonium Formate for Pesticide Analysis

Determination of 45 Pesticides in Avocado Varieties by the QuEChERS Method and Gas Chromatography-Tandem Mass Spectrometry

To begin the sample preparation using the QuEChERS method, weigh five grams of an avocado sample of interest in a 50 milliliter centrifuge tube. Add 50 microliters of the procedural internal standard or P-IS solution to the tube. Add 10 milliliters of aceto nitrile to the centrifuge tube and shake the tube at 70 RPM for five minutes.Then add 2.5 grams of ammonium formate to it and shake the tube again at 70 RPM for five minutes. Subsequently, centrifuge the tube at 1, 800 G for five minutes. Next, in a two milliliter centrifuge tube, take the appropriate amounts of the reagents displayed on the screen.Then add one milliliter of the extract into the tube for purification using dispersive solid phase extraction. Vortex the tube for 30 seconds before centrifuging it at 1, 800 G for five minutes. Transfer 200 microliters of the purified extract to an auto-sampler vial, and add 20 microliters of the analyte protectant solution, followed by adding 50 microliters of a pre-prepared triphenyl phosphate solution.Finally, perform instrumental analysis using a GC-MS/MS system.

Comprehensive validation of the analytical method was conducted according to SANTE/11312/2021 guidelines6, encompassing assessments of linearity, ME, recovery, and repeatability.
For the linearity assessment, matrix-matched calibration curves were constructed using spiked blank samples at multiple concentration levels (ranging from 5 to 600 &#181;g/kg). The determination coefficients (R2) for most of the selected pesticides were found to be higher than or equ...

Read this Scientific Article Protocol about Author Spotlight: A Matrix-Matched Calibration Approach for Mitigating Matrix Effects in Avocado Pesticide Residue Analysis at JoVE.com

The present protocol describes the analysis of multiclass pesticide residues in avocado varieties using the Quick-Easy-Cheap-Effective-Rugged-Safe (QuEChERS) method with ammonium formate, followed by gas chromatography-tandem mass spectrometry.

Gas chromatography (GC) tandem mass spectrometry (MS/MS) stands as a preeminent analytical instrument extensively employed for the surveillance of ...

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GC-MS/MS Analysis and Data Acquisition for Assessing Pesticides in Avocado Samples Prepared by the QuEChERS Method

408 Views.  Universidad EAN.  The present protocol describes the analysis of multiclass pesticide residues in avocado varieties using the Quick-Easy-Cheap-Effective-Rugged-Safe (QuEChERS) method with ammonium formate, followed by gas chromatography-tandem mass spectrometry. 

Analyzing Pesticides in Avocado Using the QuEChERS Method and CG-MS/MS

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