ORIGINAL PAPER Migration of e-caprolactam from nylon cooking utensils: validation of a liquid chromatography-ultraviolet detection method Juana Bustos • Raquel Sendo ´n • Jose Juan Sa ´nchez • Perfecto Paseiro • Ma Eugenia Cirugeda Received: 5 June 2009 / Revised: 1 October 2009 / Accepted: 11 October 2009 / Published online: 30 October 2009 Ó Springer-Verlag 2009 Abstract A large amount of modern cooking utensils are made of nylon. This is the generic name of polyamides that are polymers having characteristic amide linkages. Cap- rolactam is the monomer used in the synthesis of nylon 6. This work presents the validation of an LC-UV method for the determination of caprolactam in the aqueous food simulant 3% acetic acid (w/v) employing capryllactam as internal standard. LC–MS/MS was the confirmation tech- nique. The obtained detection and quantification limits were satisfactory regarding caprolactam specific migration limit; these were 0.6 and 2 mg kg -1 , respectively. The working range was 2–30 mg kg -1 and the correlation coefficients (r) were in all cases at least 0.999. The intra- day repeatability was between 2.5 and 4.8% depending on the validation level. The global mean recovery was 100.6% with a RSD (%) of 5.0%. Different nylon cooking utensils were analyzed for the migration of caprolactam in the food simulant acetic acid 3% p/v. Conditions used were repeated exposure to the simulant for 2 h at 100 °C, and the results obtained after the third exposure were in compliance regarding Directive 2002/72/EC. With the aim of identi- fying the polymer used in these utensils, IR spectra were also obtained for all samples. Keywords Food contact materials  Caprolactam  Migration  LC-UV  LC–MS/MS  Nylon cooking utensils Introduction A large amount of modern cooking utensils are made of nylon. These type of cookware (i.e. turners, whisks and spoons for cooking and frying) are nowadays broadly used because they are cheap, unbreakable (resist high tempera- tures), and do not scratch other surfaces. Because they are intended to come into contact with food they should be framed in the European food contact materials legislation. Nylon is the generic name of polyamides that are polymers having characteristic amide linkages. The amide groups can interact with each other by hydrogen bond. Because of this, and because the polyamide backbone is regular and symmetrical, nylons are often crystalline, and make very good fibers. There are several classes of polyamides formed from different starting substances. One type is formed from cyclic monomers like nylon 6 and nylon 12 which are made from caprolactam (six carbon atoms per repeat unit) and laurolactam (12 carbon atoms per repeat unit), respectively. In this case the single index used indicates the number of carbons in the repeat unit. Other type of nylon is formed from various diamines and diacids and their nomenclature involves two indexes indicating the number of carbons in the diamine and diacid units, respectively; e.g., nylon 66 is made from hexamethylene diamine and adipic acid [1]. Other kinds of nylons are available like nylon 6/66, nylon 6/12, nylon 6/69 that are made from condensation of cap- rolactam and other diamines and diacids. During last years nylon was associated with casings for sausages and cooked meats and also with bags (mono- or J. Bustos (&)  J. J. Sa ´nchez  M. E. Cirugeda Monomers and Additives Section, Chemical Area, National Food Centre, Spanish Food Safety and Nutrition Agency, Majadahonda, 28220 Madrid, Spain e-mail: Jbustos@msps.es R. Sendo ´n  P. Paseiro Department of Analytical Chemistry, Nutrition and Bromatology, Faculty of Pharmacy, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain e-mail: raquel.sendon@usc.es 123 Eur Food Res Technol (2009) 230:303–313 DOI 10.1007/s00217-009-1171-4