title: Non-targeted detection of milk powder adulteration using Raman spectroscopy and chemometrics: melamine case study.
abstract: Raman spectroscopy in combination with chemometrics was explored as a rapid, non-targeted screening method for the detection of milk powder (MP) adulteration using melamine as an example contaminant. Raman spectroscopy and an unsupervised pattern-recognition method, principal component analysis (PCA), allowed for the differentiation of authentic MPs from adulterated ones at concentrations > 1.0% for dry-blended (DB) samples and > 0.30% for wet-blended (WB) ones. Soft independent modelling of class analogy (SIMCA), a supervised pattern-recognition method, was also used to classify test samples as adulterated or authentic. Combined statistics at a 97% confidence level from the SIMCA models correctly classified adulteration of MP with melamine at concentrations ≥ 0.5% for DB samples and ≥ 0.30% for WB ones, while no false-positives from authentic MPs were found when the spectra in the 600-700 cm-1range were pre-processed using standard normal variate (SNV) followed by a gap-segment derivatisation. The combined technique of Raman spectroscopy and chemometrics proved to be a useful tool for the rapid and cost-efficient non-targeted detection of adulteration in MP at per cent spiking levels.
authors.affiliation: a US Food and Drug Administration (USFDA), Center for Food Safety and Applied Nutrition , Office of Regulatory Science , College Park , MD , USA.
authors.forename: Sanjeewa R
authors.initials: SR
authors.lastname: Karunathilaka
authors.affiliation: a US Food and Drug Administration (USFDA), Center for Food Safety and Applied Nutrition , Office of Regulatory Science , College Park , MD , USA.
authors.forename: Samantha
authors.initials: S
authors.lastname: Farris
authors.affiliation: a US Food and Drug Administration (USFDA), Center for Food Safety and Applied Nutrition , Office of Regulatory Science , College Park , MD , USA.
authors.forename: Magdi M
authors.initials: MM
authors.lastname: Mossoba
authors.affiliation: b US Pharmacopeial Convention , Rockville , MD , USA.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Moore
authors.affiliation: a US Food and Drug Administration (USFDA), Center for Food Safety and Applied Nutrition , Office of Regulatory Science , College Park , MD , USA.
authors.forename: Betsy Jean
authors.initials: BJ
authors.lastname: Yakes
mesh_terms: D000818:Animals; D005506:Food Contamination / Q000032:analysis*; D008892:Milk / Q000737:chemistry*; D011208:Powders; D025341:Principal Component Analysis; D012984:Software; D013059:Spectrum Analysis, Raman; D014227:Triazines / Q000032:analysis*
chemical_list: D011208:Powders; D014227:Triazines; C011907:melamine
keywords: PCA; Raman spectroscopy; Skim milk powder (SMP); classification; economic adulteration; non-fat dry milk powder (NFDM); non-targeted detection; soft independent modelling of class analogy (SIMCA)