Detection of melamine using commercial enzyme-linked immunosorbent assay technology.
Recent cases of adulteration with melamine have led to the need for rapid and reliable screening methods. To meet this need, commercial enzyme-linked immunosorbent assay (ELISA) test kits for the detection of triazines were evaluated. The recently released Melamine Plate kit (Abraxis, Warminster, Pa.) displayed a limit of detection of 9 ng/ml for melamine in phosphate-buffered saline (PBS) and approximately 1 microg/ml for melamine added to dog food. An atrazine ELISA test kit produced by Abraxis required 0.2 mg/ml to generate a response more than four times the standard deviation from background. In contrast, with the EnviroGard Triazine Plate kit (Strategic Diagnostics, Inc., Newark, Del.), 1.5 mg/ml melamine in PBS generated a signal only one standard deviation from background, which was insufficient to define a limit of detection. Extraction based on dilution with 105 mM sodium phosphate/75 mM NaCl/2.5% nonfat milk/0.05% Tween 20 (UD) enabled detection of fivefold less melamine in dog food than did use of the procedure recommended by the manufacturer, which entailed extraction into 60% methanol, sonication, centrifugation, filtration, and further dilution into 10% methanol/PBS. Using the Abraxis Melamine ELISA, both extraction protocols yielded identical results with a dog food sample adulterated with melamine. The recovery of melamine spiked into gravy from dog food using UD was 74% +/- 4%. In conclusion, the recently released Abraxis ELISA for melamine proved to be a useful alternative to more cumbersome methods.
Garber
Eric A E
EA
Division of Bioanalytical Chemistry, Office of Regulatory Science, Center for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, Maryland 20740, USA. eric.garber@fda.hhs.gov
D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D003257:Consumer Product Safety; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005506:Food Contamination / Q000032:analysis*; D006540:Herbicides / Q000032:analysis*; D006801:Humans; D010573:Pesticide Residues / Q000032:analysis; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014227:Triazines / Q000032:analysis*
D006540:Herbicides; D010573:Pesticide Residues; D011933:Reagent Kits, Diagnostic; D014227:Triazines; C011907:melamine