title: Combined determination and confirmation of ethylenethiourea and propylenethiourea residues in fruits at low levels of detection.
abstract: In this work, a new method for the determination of ethylenethiourea (ETU) and propylenethiourea (PTU) in fruits and vegetables is presented. Different extraction and purification techniques, including matrix solid phase dispersion (MSPD) and solid-liquid extraction (SLE), followed by a clean-up step by solid phase extraction (SPE), were compared. The determination of ETU and PTU was performed by high performance liquid chromatography with diode array detection (HPLC/DAD) or by gas chromatography with mass spectrometry detection (GC/MS). The effect of several parameters on the extraction, separation and detection was studied. The proposed method based on solid-liquid extraction with acetonitrile, clean-up with Envicarb II/PSA cartridges and subsequent analysis by HPLC/DAD was characterised and applied to the analysis of fruits and vegetables from different countries. Analytes recoveries were between 71% and 94% with relative standard deviations (RSDs) ranging from 8% to 9.5%. Quantification limits obtained for ETU and PTU with the HPLC/DAD method were 7 and 16 μg kg⁻¹ in strawberries (fresh weight), respectively. For apples, they were 11 and 25 μg kg⁻¹, respectively.
authors.affiliation: Nutrition and Bromatology Group, Analytical and Food Chemistry Department, Faculty of Sciences, University of Vigo, Ourense Campus, E-32004 Ourense, Spain.
authors.forename: O
authors.initials: O
authors.lastname: López-Fernández
authors.forename: R
authors.initials: R
authors.lastname: Rial-Otero
authors.forename: A
authors.initials: A
authors.lastname: Cid
authors.forename: J
authors.initials: J
authors.lastname: Simal-Gándara
mesh_terms: D018556:Crops, Agricultural / Q000737:chemistry*; D005031:Ethylenethiourea / Q000032:analysis* / Q000737:chemistry; D005506:Food Contamination; D005513:Food Inspection / Q000379:methods; D031985:Fragaria / Q000737:chemistry; D005612:Freeze Drying; D005638:Fruit / Q000737:chemistry*; D005659:Fungicides, Industrial / Q000032:analysis* / Q000737:chemistry; D018545:Lactuca / Q000737:chemistry; D057230:Limit of Detection; D027845:Malus / Q000737:chemistry; D019083:Mediterranean Region; D010316:Particle Size; D010573:Pesticide Residues / Q000032:analysis* / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification; D018515:Plant Leaves / Q000737:chemistry; D015203:Reproducibility of Results; D013030:Spain; D013859:Thiocarbamates / Q000032:analysis / Q000737:chemistry; D013890:Thiourea / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D027843:Vitis / Q000737:chemistry
chemical_list: D005659:Fungicides, Industrial; D010573:Pesticide Residues; D010936:Plant Extracts; D013859:Thiocarbamates; C035039:propylenethiourea; D005031:Ethylenethiourea; D013890:Thiourea
keywords: Dithiocarbamate metabolites; Ethylenethiourea (ETU); Fruits; Propylenethiourea (PTU); Vegetables