Characterization of newfound natural luminescent properties of melamine, and development and validation of a method of high performance liquid chromatography with fluorescence detection for its determination in kitchen plastic ware

• Published in: Talanta (Oxford) Vol. 123; pp. 128 - 134
• Main Authors: de Lourdes Mendes Finete, Virginia, Martins Gouvêa, Marcos, de Carvalho Marques, Flávia Ferreira, Duarte Pereira Netto, Annibal
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-06-2014
• Subjects: Chromatography, High Pressure Liquid - methods; Cooking and Eating Utensils; Extraction; Fluorescence; Fluorescence of natural melamine; Food Contamination - analysis; High performance liquid chromatography; HPLC–fluorescence detection; Hydrogen-Ion Concentration; Kitchen melamine plastic ware; Kitchens; Luminescence; Mathematical analysis; Melamine; Melamine determination; Microwaves; Ovens; Plastics - analysis; Plastics - chemistry; Reproducibility of Results; Solvents - chemistry; Spectrometry, Fluorescence - methods; Triazines - analysis; Triazines - chemistry; Triazines - isolation & purification; Melamine determination; Kitchen melamine plastic ware; HPLC–fluorescence detection; Fluorescence of natural melamine
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2014.02.012

Experimental studies of the natural photoluminescence of melamine in aqueous solutions showed that its fluorescence intensity (at 250/365nm) was appropriated for analytical purposes. The exploitation of such melamine property provided the basis of development of a new, simple, precise and accurate method based on high performance liquid chromatography with fluorescence detection (HPLC–Fluo) to determine melamine in kitchen plastic ware following aqueous extraction using a microwave oven. Optimization of analytical parameters such as solvent composition, pH and extraction conditions led to limits of detection and quantification of melamine of 0.0081 and 0.027μgmL−1, respectively, with a linear range up to 10μgmL−1. Sample extracts fortified with melamine at three concentration levels produced an average recovery of 98±6%, which was in agreement with the results achieved with a reference HPLC–UV method. Different samples of kitchen plastic ware analyzed by the developed and optimized method showed melamine concentrations in the aqueous extract up to 17µgmL−1, which corresponded to 86.0mgkg−1 in these utensils. The results obtained indicate that the use of kitchen plastic ware made of melamine can contaminate food with this compound after heating in a microwave oven.
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•Melamine emits an intense fluorescence signal in aqueous solutions.•Fluorescence was used to develop a new HPLC method with fluorescence detection.•Melamine was measured in kitchen plastic ware extracts obtained in microwave oven.•Low levels of melamine were found in the extracts.•A possible pathway for food contamination with melamine is indicated.