title: Development and application of an indirect competitive enzyme-linked immunoassay for aflatoxin m(1) in milk and milk-based confectionery.
abstract: High-titer rabbit polyclonal antibodies to aflatoxin M(1) (AFM1) were produced by utilizing AFM1-bovine serum albumin (BSA) conjugate as an immunogen. An indirect competitive enzyme-linked immunosorbent assay was standardized for estimating AFM1 in milk and milk products. To avoid the influence of interfering substances present in the milk samples, it was necessary to prepare AFM1 standards in methanol extracts of certified reference material (CRM) not containing detectable AFM1 (< 0.05 ng/g). The reliability of the procedure was assessed by using CRM with AFM1 concentrations of < 0.5 and 0.76 ng/g. Also, assays of milk samples mixed with AFM1 ranging in concentration between 0.5 and 50 ng/L gave recoveries of > 93%. The relative cross-reactivity with aflatoxins (AF) and ochratoxin A, assessed as the amount of AFM1 necessary to cause 50% inhibition of binding, was 5% for AFB1 and much less for AFB2, AFG1, and AFG2; there was no reaction with ochratoxin A. AFM1 contamination was measured in retail milk and milk products collected from rural and periurban areas in Andhra Pradesh, India. Of 280 milk samples tested, 146 were found to contain < 0.5 ng/mL of AFM1; in 80 samples it varied from 0.6 to 15 ng/mL, in 42 samples from 16 to 30 ng/mL, and in 12 samples from 31 to 48 ng/mL. Most of the milk samples that contained high AFM1 concentrations were obtained from periurban locations. The results revealed a significant exposure of humans to AFM1 levels in India and thus highlight the need for awareness of risk among milk producers and consumers.
authors.affiliation: International Crops Research Institute for the Semi-Arid Tropics, Patancheru, Andhra Pradesh, India.
authors.forename: K
authors.initials: K
authors.lastname: Thirumala-Devi
authors.forename: M A
authors.initials: MA
authors.lastname: Mayo
authors.forename: A J
authors.initials: AJ
authors.lastname: Hall
authors.forename: P Q
authors.initials: PQ
authors.lastname: Craufurd
authors.forename: T R
authors.initials: TR
authors.lastname: Wheeler
authors.forename: F
authors.initials: F
authors.lastname: Waliyar
authors.forename: A
authors.initials: A
authors.lastname: Subrahmanyam
authors.forename: D V R
authors.initials: DV
authors.lastname: Reddy
mesh_terms: D016607:Aflatoxin M1 / Q000032:analysis*; D000818:Animals; D000918:Antibody Specificity; D001667:Binding, Competitive; D002182:Candy / Q000032:analysis; D003611:Dairy Products / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005506:Food Contamination; D006801:Humans; D007194:India; D007223:Infant; D007225:Infant Food / Q000032:analysis; D008892:Milk / Q000737:chemistry*; D009793:Ochratoxins / Q000032:analysis
chemical_list: D009793:Ochratoxins; C025589:ochratoxin A; D016607:Aflatoxin M1