title: Use of ammonium formate in QuEChERS for high-throughput analysis of pesticides in food by fast, low-pressure gas chromatography and liquid chromatography tandem mass spectrometry.
abstract: The "quick, easy, cheap, effective, rugged, and safe" (QuEChERS) approach to sample preparation is widely applied in pesticide residue analysis, but the use of magnesium sulfate and other nonvolatile compounds for salting out in the method is not ideal for mass spectrometry. In this study, we developed and evaluated three new different versions of the QuEChERS method using more volatile salts (ammonium chloride and ammonium formate and acetate buffers) to induce phase separation and extraction of 43 representative pesticide analytes of different classes. Fast low-pressure gas chromatography tandem mass spectrometry (LPGC-MS/MS) and liquid chromatography (LC)-MS/MS were used for analysis. The QuEChERS AOAC Official Method 2007.01 was also tested for comparison purposes. Of the studied methods, formate buffering using 7.5g of ammonium formate and 15mL of 5% (v/v) formic acid in acetonitrile for the extraction of 15g of sample (5g for wheat grain) provided the best performance and practical considerations. Method validation was carried out with and without the use of dispersive solid-phase extraction for cleanup, and no significant differences were observed for the majority of pesticides. The method was demonstrated in quantitative analysis for GC- and LC-amenable pesticides in 4 representative food matrices (apple, lemon, lettuce, and wheat grain). With the typical exceptions of certain pH-dependent and labile pesticides, 90-110% recoveries and <10% RSD were obtained. Detection limits were mostly <5ng/g, which met the general need to determine pesticide concentrations as low as 10ng/g for monitoring purposes in food applications.
authors.affiliation: US Department of Agriculture, Agricultural Research Service, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA; Departamento de Química Analítica, Nutrición y Bromatología, Facultad de Química, Universidad de La Laguna, Avenida Astrofísico Francisco Sánchez s/n, 38206 La Laguna (Tenerife), España.
authors.forename: Miguel Ángel
authors.initials: MÁ
authors.lastname: González-Curbelo
authors.affiliation: US Department of Agriculture, Agricultural Research Service, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA. Electronic address: Steven.Lehotay@ars.usda.gov.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Lehotay
authors.affiliation: Departamento de Química Analítica, Nutrición y Bromatología, Facultad de Química, Universidad de La Laguna, Avenida Astrofísico Francisco Sánchez s/n, 38206 La Laguna (Tenerife), España.
authors.forename: Javier
authors.initials: J
authors.lastname: Hernández-Borges
authors.affiliation: Departamento de Química Analítica, Nutrición y Bromatología, Facultad de Química, Universidad de La Laguna, Avenida Astrofísico Francisco Sánchez s/n, 38206 La Laguna (Tenerife), España.
authors.forename: Miguel Ángel
authors.initials: MÁ
authors.lastname: Rodríguez-Delgado
mesh_terms: D002021:Buffers; D002849:Chromatography, Gas / Q000379:methods; D002853:Chromatography, Liquid / Q000379:methods; D002957:Citrus / Q000737:chemistry; D004338:Drug Combinations; D002523:Edible Grain / Q000737:chemistry; D005506:Food Contamination / Q000032:analysis; D005561:Formates / Q000737:chemistry*; D005638:Fruit / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D007306:Insecticides / Q000032:analysis*; D018545:Lactuca / Q000737:chemistry; D057230:Limit of Detection; D018942:Macrolides / Q000032:analysis; D027845:Malus / Q000737:chemistry; D009943:Organophosphorus Compounds / Q000032:analysis; D010573:Pesticide Residues / Q000032:analysis*; D052616:Solid Phase Extraction; D013453:Sulfonylurea Compounds / Q000032:analysis; D053719:Tandem Mass Spectrometry / Q000379:methods; D013844:Thiazoles / Q000032:analysis; D013876:Thiophenes / Q000032:analysis; D014227:Triazines / Q000032:analysis; D014908:Triticum / Q000737:chemistry
chemical_list: D002021:Buffers; D004338:Drug Combinations; D005561:Formates; D007306:Insecticides; D018942:Macrolides; D009943:Organophosphorus Compounds; D010573:Pesticide Residues; D013453:Sulfonylurea Compounds; D013844:Thiazoles; D013876:Thiophenes; D014227:Triazines; C030544:formic acid; C414314:thifensulfuron methyl; C480311:pymetrozine; C041191:tricyclazole; C415329:spinosad
keywords: Ammonium formate buffering; High-throughput analysis; Pesticide residue monitoring; QuEChERS; Sample preparation