Skip to Content
Merck
  • Validation of a rapid method of analysis using ultrahigh-performance liquid chromatography - tandem mass spectrometry for nitrogen-rich adulterants in nutritional food ingredients.

Validation of a rapid method of analysis using ultrahigh-performance liquid chromatography - tandem mass spectrometry for nitrogen-rich adulterants in nutritional food ingredients.

Journal of chromatography. A (2014-12-02)
Jon Draher, Vickie Pound, Todime M Reddy
ABSTRACT

A method for the rapid quantification of 9 potential nitrogen-rich economic adulterants (dicyandiamide, urea, biuret, cyromazine, amidinourea, ammeline, amidinourea, melamine, and cyanuric acid) in five milk and soy derived nutritional ingredients, i.e. whole milk powder, nonfat dry milk, milk protein concentrate, sodium caseinate, and soy protein isolate has been developed and validated for routine use. The samples were diluted tenfold with water followed by treatment with 2% formic acid and acetonitrile to precipitate proteins. Sample extracts were analyzed using hydrophilic interaction chromatography and tandem mass spectrometry (HILIC-MS/MS) under both positive and negative modes. Stable isotope labeled internal standards were used to ensure accurate quantification. In multi-day validation experiments, the average accuracies, relative standard deviations (RSD), and method detection limits (MDL) for all analytes in whole milk powder were 82-101%, 6-13%, and 0.1mg/kg-7 mg/kg, respectively. The retention times of the analytes in matrix spiked controls were within ± 0.06 min of the average retention times of the corresponding analytes in calibration standards. The validated method was proven to be rugged for routine use to quantify the presence of 9 nitrogen-rich compounds in milk and soy derived ingredients and to provide a defense from economically motivated adulteration.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Urea solution, BioUltra, ~8 M in H2O
Sigma-Aldrich
Urea-12C, 99.9 atom % 12C
Sigma-Aldrich
Melamine, 99%
Supelco
Ammonium acetate, LiChropur, eluent additive for LC-MS
Sigma-Aldrich
Dicyandiamide, 99%
Sigma-Aldrich
Ammonium acetate, reagent grade, ≥98%
Sigma-Aldrich
Ammonium acetate, BioXtra, ≥98%
Sigma-Aldrich
Ammonium acetate solution, for molecular biology, 7.5 M
Sigma-Aldrich
Urea solution, 40 % (w/v) in H2O
Millipore
Urea solution, suitable for microbiology, 40% in H2O
Sigma-Aldrich
Ammonium acetate solution, BioUltra, for molecular biology, ~5 M in H2O
Supelco
Melamine, analytical standard
Sigma-Aldrich
Ammonium acetate, for molecular biology, ≥98%
Sigma-Aldrich
Ammonium acetate, BioUltra, for molecular biology, ≥99.0%
Sigma-Aldrich
Ammonium acetate, 99.999% trace metals basis
Supelco
Melamine, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Metformin Related Compound A, Pharmaceutical Secondary Standard; Certified Reference Material
Metformin impurity A, European Pharmacopoeia (EP) Reference Standard
USP
Melamine, United States Pharmacopeia (USP) Reference Standard
Sigma-Aldrich
Ammonium acetate, ACS reagent, ≥97%
Sigma-Aldrich
Ammonium acetate, ≥99.99% trace metals basis
Supelco
Residual Solvent - Acetonitrile, Pharmaceutical Secondary Standard; Certified Reference Material
USP
Metformin Related Compound A, United States Pharmacopeia (USP) Reference Standard
Supelco
Cyanuric acid, analytical standard
Supelco
Urea, 8 M (after reconstitution with 16 mL high purity water)
Sigma-Aldrich
Acetonitrile, electronic grade, 99.999% trace metals basis
Supelco
Ammelide, analytical standard
Supelco
Acetonitrile, analytical standard
Sigma-Aldrich
Biuret, 98% (Contains ≤10%(w/w) Triuret)
Sigma-Aldrich
Urea, BioUltra, for molecular biology, 99% (T)