{ "id": "epq8jd5cf4", "slug": "quechers", "title": "QuEChERS", "updated": "2026-10-25", "topic_path": [ { "id": "physical", "label": "Physical world and mathematics", "api_url": "https://www.edgepedia.org/api/v1/topics/physical" }, { "id": "physical.chemistry", "label": "Chemistry", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry" }, { "id": "physical.chemistry.methods", "label": "Chemical principles and methods", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.methods" }, { "id": "physical.chemistry.methods.analytical-chemistry", "label": "Analytical chemistry", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.methods.analytical-chemistry" }, { "id": "physical.chemistry.methods.analytical-chemistry.extraction-and-sample-preparation", "label": "Extraction and sample preparation", "api_url": "https://www.edgepedia.org/api/v1/topics/physical.chemistry.methods.analytical-chemistry.extraction-and-sample-preparation" } ], "geo": [ { "id": "geo.nongeo.t2001.physical.chemistry.methods.analytical-chemistry", "label": "Non-geographic · 2001 to 2020: Analytical chemistry", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.physical.chemistry.methods.analytical-chemistry", "path": [ { "id": "geo.nongeo", "label": "Non-geographic", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo" }, { "id": "geo.nongeo.t2001", "label": "Non-geographic · 2001 to 2020", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001" }, { "id": "geo.nongeo.t2001.physical", "label": "Physical world and mathematics", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.physical" }, { "id": "geo.nongeo.t2001.physical.chemistry", "label": "Chemistry", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.physical.chemistry" }, { "id": "geo.nongeo.t2001.physical.chemistry.methods", "label": "Chemical principles and methods", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.physical.chemistry.methods" }, { "id": "geo.nongeo.t2001.physical.chemistry.methods.analytical-chemistry", "label": "Analytical chemistry", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.t2001.physical.chemistry.methods.analytical-chemistry" } ] } ], "excerpt": "QuEChERS, short for quick, easy, cheap, effective, rugged, and safe, is an analytical chemistry method extracting pesticide residues from food using acetonitrile and salt, followed by cleanup.", "snippet": "QuEChERS, short for quick, easy, cheap, effective, rugged, and safe, is an analytical chemistry method extracting pesticide residues from food using acetonitrile and salt, followed by cleanup.", "node": "physical.chemistry.methods.analytical-chemistry.extraction-and-sample-preparation", "markdown": "# QuEChERS\n\nQuEChERS (quick, easy, cheap, effective, rugged, and safe) is a sample-preparation method in analytical chemistry that isolates pesticide residues and other contaminants from food and environmental samples by salting-out extraction with acetonitrile, followed by dispersive solid-phase extraction (dSPE) cleanup.[1](https://doi.org/10.1093/jaoac/86.2.412) It produces a clean acetonitrile extract that can be injected directly, after simple dilution, into GC-MS or LC-MS/MS instruments, and the same extract can serve both GC and LC analysis.[2](https://pubmed.ncbi.nlm.nih.gov/21643905/) • [3](https://www.sciencedirect.com/science/article/abs/pii/S221415881830028X) Extraction of a homogenized sample takes less than 30 minutes, cleanup less than 30 minutes more, and in most cases no concentration step is needed.[3](https://www.sciencedirect.com/science/article/abs/pii/S221415881830028X) These traits made it a very flexible multiresidue method for pesticide analysis in produce, and two buffered versions hold official status as AOAC Official Method 2007.01 and CEN Standard Method EN 15662.[2](https://pubmed.ncbi.nlm.nih.gov/21643905/)\n\n| Key fact | Detail |\n|---|---|\n| What the acronym means | Quick, Easy, Cheap, Effective, Rugged, and Safe[2](https://pubmed.ncbi.nlm.nih.gov/21643905/) |\n| Product | A cleaned acetonitrile extract for GC-MS and LC-MS/MS, usable for both in parallel[2](https://pubmed.ncbi.nlm.nih.gov/21643905/) • [3](https://www.sciencedirect.com/science/article/abs/pii/S221415881830028X) |\n| Core chemistry | Salting-out of acetonitrile from water with MgSO₄ and NaCl, then dSPE with PSA, C18, and optionally GCB[4](https://phenomenex.blob.core.windows.net/documents/4d3b8d56-2072-4df0-951e-3ed29e39530f.pdf) • [5](https://pmc.ncbi.nlm.nih.gov/articles/PMC5757139/) |\n| Official versions | AOAC 2007.01 (acetate buffer) and EN 15662 (citrate buffer)[2](https://pubmed.ncbi.nlm.nih.gov/21643905/) |\n| Typical recoveries | Mostly 70–120% with RSD ≤ 20% across matrices at 0.005–0.050 mg/kg[6](https://www.eurl-pesticides.eu/userfiles/file/EurlFV/methods/EURL-FV%20%282022-M52%29.pdf) |\n| Throughput and cost | 10 chopped samples in about 30 minutes, about $1 of materials per sample[7](https://agresearchmag.ars.usda.gov/ar/archive/2003/jul/quech0703.pdf) |\n| Solvent waste | Under 10 mL per sample, versus 75–450 mL for other methods[7](https://agresearchmag.ars.usda.gov/ar/archive/2003/jul/quech0703.pdf) |\n\n## How it works\n\nThe method rests on the partition behavior of acetonitrile in a salted aqueous matrix. Adding anhydrous magnesium sulfate absorbs water and increases the ionic strength of the aqueous phase, which induces phase separation between acetonitrile and water; the acetonitrile layer carries the analytes.[4](https://phenomenex.blob.core.windows.net/documents/4d3b8d56-2072-4df0-951e-3ed29e39530f.pdf) [Acetonitrile](https://www.edgepedia.org/acetonitrile) is the solvent of choice because it separates from water by salt partitioning, extracts fewer matrix interferences than alternatives, and the resulting extract suits both GC and LC injection.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC5757139/) The MgSO₄/NaCl combination gave the most effectively tailored phase separation, avoiding co-extraction of proteins and sugars.[8](https://www.chromatographyonline.com/view/the-quecherser-mega-method)\n\nThe cleanup step is dispersive SPE: sorbent powder is added directly to a subsample of the extract. PSA (primary secondary amine) removes sugars, fatty acids, organic acids, and anthocyanin pigments; C18 removes nonpolar interferences such as fats and oils; GCB (graphitized carbon black) removes pigments, sterols, and nonpolar interferences; MgSO₄ removes residual water.[9](https://discover.restek.com/wp-content/uploads/FSAR3917.pdf) • [10](https://www.waters.com/nextgen/us/en/products/sample-preparation/disque--quechers-sample-preparation-products.html)\n\n## How it is done\n\nAll versions follow two stages: extraction with solvent and salts, then dSPE cleanup of a subsample of the organic layer.[11](https://discover.restek.com/wp-content/uploads/803-01-005.pdf)\n\nOriginal unbuffered and EN 15662 (citrate): weigh 10 g of homogenized sample, add 10 mL acetonitrile, then a salt packet of 4 g anhydrous MgSO₄ plus 1 g NaCl (unbuffered) or that plus 1 g trisodium citrate dihydrate and 0.5 g disodium hydrogen citrate sesquihydrate (citrate-buffered).[12](https://www.go-jsb.co.uk/resources/media/assortiment/manuals/Lehotay_etal_Comparison_various_QuEChERS_extractions_2010_J_Chrom_A_40852PDF1944.pdf) • [6](https://www.eurl-pesticides.eu/userfiles/file/EurlFV/methods/EURL-FV%20%282022-M52%29.pdf) The tube is shaken and centrifuged (EN 15662 specifies over 3000 × g for 5 minutes).[13](http://global.shimadzu-sglc.com/sites/default/files/pdf/2026-01/SGLC-SPE-006A%20SHIMSEN%20QuEChERS_0.pdf) EN 15662 also calls for pH adjustment with 5 N NaOH before extraction if the sample pH is below 5 (600 µL below pH 3, 200 µL between pH 3 and 5).[11](https://discover.restek.com/wp-content/uploads/803-01-005.pdf)\n\nAOAC 2007.01 (acetate): weigh 15 g of sample, add 15 mL of 1% acetic acid in acetonitrile and a packet of 6 g anhydrous MgSO₄ plus 1.5 g anhydrous sodium acetate, shake, and centrifuge.[11](https://discover.restek.com/wp-content/uploads/803-01-005.pdf) • [14](https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/application::paper.paper/5378f26f-a27c-4e65-b4b4-d7f73bc2fa73.pdf)\n\nCleanup: transfer a portion of the acetonitrile layer to a tube with 150 mg anhydrous MgSO₄ plus 50 mg PSA per mL of extract, shake, and centrifuge again.[15](https://doi.org/10.1093/jaoac/88.2.615) Dry commodities such as cereals, dried fruits, or tea need water added before extraction, generally to a roughly 1:1 water-to-solvent ratio (about 10–15 mL total water), to weaken analyte-matrix interactions and ensure partitioning.[16](https://www.quechers.eu/method) • [9](https://discover.restek.com/wp-content/uploads/FSAR3917.pdf) The final extract is analyzed directly by GC-MS or LC-MS/MS after simple dilution.[10](https://www.waters.com/nextgen/us/en/products/sample-preparation/disque--quechers-sample-preparation-products.html)\n\n## Origin\n\nQuEChERS was introduced in 2003 by Michelangelo Anastassiades and colleagues, in the paper \"Fast and Easy Multiresidue Method Employing Acetonitrile Extraction/Partitioning and 'Dispersive Solid-Phase Extraction' for the Determination of Pesticide Residues in Produce,\" published in the Journal of AOAC International.[1](https://doi.org/10.1093/jaoac/86.2.412) The acetate-buffered variant, the basis of AOAC Official Method 2007.01, was introduced by Steven J Lehotay, Kateřina Maštovská, and Alan R Lightfield in the Journal of AOAC International in 2005.[15](https://doi.org/10.1093/jaoac/88.2.615) Maštovská, Lehotay, and Anastassiades introduced analyte protectants to overcome GC matrix effects in Analytical Chemistry in 2005.[17](https://doi.org/10.1021/ac0515576) Uptake was rapid: from publication in March 2003 to March 2023 the introducing paper received almost 4,000 citations in [Web of Science](https://www.edgepedia.org/web-of-science), and both buffered versions met interlaboratory performance criteria to achieve official status as AOAC Official Method 2007.01 and CEN Standard Method EN 15662.[18](https://link.springer.com/article/10.1007/s44169-024-00073-1) • [2](https://pubmed.ncbi.nlm.nih.gov/21643905/)\n\n## Variants\n\nThe three main versions differ in their salt packets: unbuffered uses 4 g MgSO₄ plus 1 g NaCl per 10 g sample; acetate-buffered uses 6 g MgSO₄ plus 1.5 g sodium acetate; citrate-buffered adds 1 g trisodium citrate dihydrate and 0.5 g disodium hydrogen citrate sesquihydrate to the unbuffered salts.[12](https://www.go-jsb.co.uk/resources/media/assortiment/manuals/Lehotay_etal_Comparison_various_QuEChERS_extractions_2010_J_Chrom_A_40852PDF1944.pdf) AOAC salts buffer the final extract to about pH 4.75 and EN salts to pH 5.0–5.5, while with unbuffered salts the extract pH follows the sample.[9](https://discover.restek.com/wp-content/uploads/FSAR3917.pdf) In a three-way comparison of 32 pesticides in apple-blueberry sauce, peas, and limes at 50–1000 ng/g, all versions gave an overall average recovery of 98% with 10% RSD, except that the unbuffered method gave lower recoveries for pH-dependent pesticides.[12](https://www.go-jsb.co.uk/resources/media/assortiment/manuals/Lehotay_etal_Comparison_various_QuEChERS_extractions_2010_J_Chrom_A_40852PDF1944.pdf) In soil, the acetate version gave average recoveries of 72–121% (RSD < 19%), the citrate version 67–123% (RSD < 15%), and the unbuffered method fell below 70% for about 30% of 58 pesticides.[19](https://www.mdpi.com/1420-3049/27/13/4323) Cleanup can also use mini-cartridge SPE instead of dSPE; a cited effective dSPE mixture for fruits and vegetables is 150 mg MgSO₄, 50 mg PSA, 50 mg C18, and 7.5 mg GCB per mL of extract with acetate buffering.[20](https://www.sciencedirect.com/science/article/abs/pii/S0021967310006382) Zirconium-oxide sorbents (Z-Sep, Z-Sep+) combined with C18 and PSA improve cleanup of high-fat samples, and ChloroFiltr removes more than 82% of chlorophyll without loss of planar compounds.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC5757139/) • [18](https://link.springer.com/article/10.1007/s44169-024-00073-1) Micro-QuEChERS reduces sample mass to 5 g or less, a reduction of at least half versus conventional protocols that use 10–15 g of matrix, cutting solvent and sorbent waste.[21](https://www.mdpi.com/2297-8739/12/12/339) The QuEChERSER \"megamethod\" adds \"efficient and robust\" to the acronym and covers a broader polarity range of analytes in diverse matrices, using 1–5 g samples extracted with 5 mL/g of 4:1 acetonitrile-water and automated instrument-top mini-cartridge cleanup of 45 mg MgSO₄/PSA/C18/CarbonX per 300 µL extract.[18](https://link.springer.com/article/10.1007/s44169-024-00073-1) • [8](https://www.chromatographyonline.com/view/the-quecherser-mega-method)\n\n## Applications\n\nQuEChERS has been extended to pharmaceuticals, polycyclic aromatic hydrocarbons (PAHs), and persistent organic pollutants including dioxins, [polychlorinated biphenyls](https://www.edgepedia.org/polychlorinated-biphenyl), perfluoroalkyl substances, and brominated flame retardants in food, biological, and environmental matrices.[3](https://www.sciencedirect.com/science/article/abs/pii/S221415881830028X) For PAHs in fatty fish, a variant using ethyl acetate, acetone, and isooctane attained overall recoveries almost 40% higher than [Soxhlet extraction](https://www.edgepedia.org/soxhlet-extraction), and QuEChERS determined PCBs in fish with LOQs below 1 ng/g.[5](https://pmc.ncbi.nlm.nih.gov/articles/PMC5757139/) In QuEChERS-based PFAS methods, acetonitrile was the extraction solvent in 95% of reviewed methods, with mild acidification (0.1–1.5% formic or acetic acid) improving recovery of the organic phase.[22](https://iris.unimore.it/retrieve/a4c8e2eb-8ea8-400d-a18f-e91c0188c71d/foods-Galluzzo%20may2026.pdf)\n\n## Limitations and alternatives\n\nIn an EURL validation across zucchini, orange, and avocado at 0.005 and 0.050 mg/kg, most recoveries for 33 pesticides fell within 70–120% with RSD ≤ 20% using citrate-buffered QuEChERS.[6](https://www.eurl-pesticides.eu/userfiles/file/EurlFV/methods/EURL-FV%20%282022-M52%29.pdf) Against traditional methods, QuEChERS offers at least fourfold lower material costs and fourfold greater throughput per analyst, and generates under 10 mL of solvent waste versus 75–450 mL.[7](https://agresearchmag.ars.usda.gov/ar/archive/2003/jul/quech0703.pdf) Its main trade-off against conventional SPE is enrichment: micro-QuEChERS gives enrichment factors of 10–50 for PAHs in water versus 100–1000 for SPE.[21](https://www.mdpi.com/2297-8739/12/12/339)\n\nKnown failure modes include hydrophilic analytes that do not partition into the acetonitrile layer during salting-out, PSA that retains LC-amenable carboxylic acid analytes, and acetonitrile-rich extracts that give poor peak shapes for early-eluting compounds in reversed-phase LC.[8](https://www.chromatographyonline.com/view/the-quecherser-mega-method) PSA's basicity can hydrolyze alkali-sensitive pesticides; more than half of 25 herbicides in one study lost 23–80% recovery with 50 mg PSA per mL, while 50 mg C18 per mL achieved 72–108%.[19](https://www.mdpi.com/1420-3049/27/13/4323) GCB strongly retains planar pesticides such as thiabendazole and chlorothalonil.[18](https://link.springer.com/article/10.1007/s44169-024-00073-1) Highly non-polar pesticides in fatty matrices give low but consistent recoveries below 70%,[16](https://www.quechers.eu/method) and PSA's anion-exchange properties can retain ionizable PFAS, dropping recoveries below 50% for some carboxylates at high PSA amounts.[22](https://iris.unimore.it/retrieve/a4c8e2eb-8ea8-400d-a18f-e91c0188c71d/foods-Galluzzo%20may2026.pdf) On the green-chemistry side, natural deep eutectic solvents (NADES) have been benchmarked against QuEChERS: a thymol:menthol (1:1) extraction for eleven pesticides in orange, wheat, and spinach scored 0.65 on the AGREEprep greenness metric, above both AOAC 2007.01 and a miniaturized QuEChERS, with LOQs of 10 µg/kg and no salting-out or cleanup steps; the driver is partly acetonitrile's toxicity profile, which is classified as problematic for safety, health, and environment.[23](https://link.springer.com/article/10.1038/s41538-026-00717-7)\n\n## References\n\n1. [Michelangelo Anastassiades and colleagues (2003). Fast and Easy Multiresidue Method Employing Acetonitrile Extraction/Partitioning and “Dispersive Solid-Phase Extraction” for the Determination of Pesticide Residues in Produce. Journal of AOAC International.](https://doi.org/10.1093/jaoac/86.2.412)\n2. [QuEChERS sample preparation approach for mass spectrometric analysis of pesticide residues in foods (Lehotay, 2011, Methods Mol Biol)](https://pubmed.ncbi.nlm.nih.gov/21643905/)\n3. [Review of the QuEChERS method for the analysis of organic pollutants: Persistent organic pollutants, polycyclic aromatic hydrocarbons, and pharmaceuticals (Trends in Environmental Analytical Chemistry, 2019)](https://www.sciencedirect.com/science/article/abs/pii/S221415881830028X)\n4. [Frequently Asked Questions (FAQ), QuEChERS (Phenomenex)](https://phenomenex.blob.core.windows.net/documents/4d3b8d56-2072-4df0-951e-3ed29e39530f.pdf)\n5. [Application of QuEChERS for Determining Xenobiotics in Foods of Animal Origin (J AOAC Int / PMC)](https://pmc.ncbi.nlm.nih.gov/articles/PMC5757139/)\n6. [EURL FV (2022 M52) (eurl-pesticides.eu)](https://www.eurl-pesticides.eu/userfiles/file/EurlFV/methods/EURL-FV%20%282022-M52%29.pdf)\n7. [QuEChERS Method Catches Pesticide Residues (Agricultural Research, July 2003)](https://agresearchmag.ars.usda.gov/ar/archive/2003/jul/quech0703.pdf)\n8. [The QuEChERSER Mega-Method (LCGC, article by the method's co-developer)](https://www.chromatographyonline.com/view/the-quecherser-mega-method)\n9. [How to Use QuEChERS for Diverse Sample Types (Restek application note)](https://discover.restek.com/wp-content/uploads/FSAR3917.pdf)\n10. [DisQuE, QuEChERS Sample Preparation Products (Waters)](https://www.waters.com/nextgen/us/en/products/sample-preparation/disque--quechers-sample-preparation-products.html)\n11. [QuEChERS Sample Preparation Procedures (Restek)](https://discover.restek.com/wp-content/uploads/803-01-005.pdf)\n12. [Comparison of QuEChERS sample preparation methods for the analysis of pesticide residues in fruits and vegetables (Lehotay et al., J. Chromatogr. A 1217 (2010) 2548–2560)](https://www.go-jsb.co.uk/resources/media/assortiment/manuals/Lehotay_etal_Comparison_various_QuEChERS_extractions_2010_J_Chrom_A_40852PDF1944.pdf)\n13. [SHIMSEN QuEChERS Product Guidebook (Shimadzu)](http://global.shimadzu-sglc.com/sites/default/files/pdf/2026-01/SGLC-SPE-006A%20SHIMSEN%20QuEChERS_0.pdf)\n14. [roQ QuEChERS Kits User Guide (manufacturer protocol document)](https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/application::paper.paper/5378f26f-a27c-4e65-b4b4-d7f73bc2fa73.pdf)\n15. [Steven J Lehotay, Kateřina Maštovská, Alan R Lightfield (2005). Use of Buffering and Other Means to Improve Results of Problematic Pesticides in a Fast and Easy Method for Residue Analysis of Fruits and Vegetables. Journal of AOAC International.](https://doi.org/10.1093/jaoac/88.2.615)\n16. [QuEChERS: About the method](https://www.quechers.eu/method)\n17. [Kateřina Maštovská, Steven J. Lehotay, Michelangelo Anastassiades (2005). Combination of Analyte Protectants To Overcome Matrix Effects in Routine GC Analysis of Pesticide Residues in Food Matrixes. Analytical Chemistry.](https://doi.org/10.1021/ac0515576)\n18. [Overview of the Evolution and Trends of the QuEChERS Sample Preparation Procedure (Reviews of Environmental Contamination and Toxicology, 2024)](https://link.springer.com/article/10.1007/s44169-024-00073-1)\n19. [Pesticide-Residue Analysis in Soils by the QuEChERS Method: A Review (Molecules, 2022)](https://www.mdpi.com/1420-3049/27/13/4323)\n20. [High throughput analysis of 150 pesticides in fruits and vegetables using QuEChERS and low-pressure GC–TOFMS (J. Chromatogr. A)](https://www.sciencedirect.com/science/article/abs/pii/S0021967310006382)\n21. [Towards Greener Sample Preparation: A Review on Micro-QuEChERS Advances and Applications in Food, Environmental, and Biological Matrices (Separations 12(12):339)](https://www.mdpi.com/2297-8739/12/12/339)\n22. [QuEChERS-Based LC-MS/MS and HRMS Methods for PFAS Determination in Food: A Systematic Review (Foods, 2026; repository copy)](https://iris.unimore.it/retrieve/a4c8e2eb-8ea8-400d-a18f-e91c0188c71d/foods-Galluzzo%20may2026.pdf)\n23. [Natural deep eutectic solvents as a sustainable alternative for multi-class pesticide extraction in food safety analysis (npj Science of Food, 2026)](https://link.springer.com/article/10.1038/s41538-026-00717-7)\n\n---\n*Topic: Encyclopedia › Physical world and mathematics › Chemistry › Chemical principles and methods › Analytical chemistry › Extraction and sample preparation*\n\n*Initially written Sep 29, 2026 · Edited: Oct 15, 2026; Oct 25, 2026*\n\n*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*\n\nLicense: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license\n", "same_as": [], "url": "https://www.edgepedia.org/quechers", "markdown_url": "https://www.edgepedia.org/quechers.md", "license": { "name": "Edgepedia Community License 1.0", "url": "https://www.edgepedia.org/edgepedia/license", "summary": "Free with credit, commercial use included. AI training is open to everyone. For other uses, organizations over USD 100M in revenue or 100M monthly users license separately.", "spdx": "LicenseRef-Edgepedia-Community-1.0" }, "credit": "\"QuEChERS\", Edgepedia (EdgeChat), https://www.edgepedia.org/quechers. Edgepedia Community License 1.0.", "credit_md": "\"[QuEChERS](https://www.edgepedia.org/quechers)\", Edgepedia (EdgeChat), [https://www.edgepedia.org/quechers](https://www.edgepedia.org/quechers). [Edgepedia Community License 1.0](https://www.edgepedia.org/edgepedia/license).", "credit_html": "\"QuEChERS\", Edgepedia (EdgeChat), https://www.edgepedia.org/quechers. Edgepedia Community License 1.0.", "speakable": "QuEChERS, short for quick, easy, cheap, effective, rugged, and safe, is an analytical chemistry method extracting pesticide residues from food using acetonitrile and salt, followed by cleanup." }