Development of enzyme-linked immunosorbent assays for Sudan dyes in chilli powder, ketchup and egg yolk.
This study aimed at developing sensitive competitive enzyme-linked immunosorbent assays (ELISAs) for the banned Sudan dyes using polyclonal antibodies. Three different formats were developed and characterized in terms of sensitivity, selectivity and rapidity. A competitive indirect ELISA was developed, which showed an IC(50) of 3.8 microg l(-1). Two competitive direct ELISAs were also developed, in which the antibody was added before or simultaneously with the other reagents; the first showed an IC(50) of 8.3 microg l(-1) and the latter showed an IC(50) of 4.9 microg l(-1). Nevertheless, considering dilution of extracts which is needed to offset matrix interference, the limits of detection of the three formats were substantially the same (10 microg kg(-1)). The antibodies in all three test formats were able to recognize Sudan I and partially Sudan II, III and IV; no cross-reactivity was observed with the five edible dyes. Twenty food samples, including chilli powder, paprika, ketchup, and egg, were extracted by a simple sample preparation and very limited dilution. Extracts were analyzed by the developed competitive direct ELISA with the simultaneous addition of reagents. A good correlation was observed (y = 1.19 x-10.0, r(2) = 0.991, n = 20) when the data was compared with that obtained through a conventional HPLC method.
Anfossi
Laura
L
Department of Analytical Chemistry, University of Turin, Torino, 10125 Italy. laura.anfossi@unito.it
Baggiani
Claudio
C
Giovannoli
Cristina
C
Giraudi
Gianfranco
G
D001391:Azo Compounds / Q000032:analysis; D002212:Capsicum / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003212:Condiments / Q000032:analysis*; D004530:Egg Yolk / Q000737:chemistry*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005505:Food Coloring Agents / Q000032:analysis*; D005506:Food Contamination / Q000032:analysis; D009284:Naphthols / Q000032:analysis; D012015:Reference Standards
D001391:Azo Compounds; D005505:Food Coloring Agents; D009284:Naphthols; C024336:1-phenylazo-2-naphthol; C033003:sudan red; C009213:Scarlet Red; C033006:sudan III