title: Optimization and validation of a method for the determination of the refractive index of milk serum based on the reaction between milk and copper(II) sulfate to detect milk dilutions.
abstract: We report the use of a method to determine the refractive index of copper(II) serum (RICS) in milk as a tool to detect the fraudulent addition of water. This practice is highly profitable, unlawful, and difficult to deter. The method was optimized and validated and is simple, fast and robust. The optimized method yielded statistically equivalent results compared to the reference method with an accuracy of 0.4% and quadrupled analytical throughput. Trueness, precision (repeatability and intermediate precision) and ruggedness are determined to be satisfactory at a 95.45% confidence level. The expanded uncertainty of the measurement was ±0.38°Zeiss at the 95.45% confidence level (k=3.30), corresponding to 1.03% of the minimum measurement expected in adequate samples (>37.00°Zeiss).
authors: Laboratório de Físico-Química de Produtos de Origem Animal - POA/PL, Laboratório Nacional Agropecuário do Estado de Minas Gerais - LANAGRO/MG, Avenida Rômulo Joviano, s/n, Caixa Postal 35 e 50, Pedro Leopoldo, MG CEP 33600-000, Brazil; Centro Federal de Educação Tecnológica de Minas Gerais - CEFET-MG, Avenida Amazonas, 5253, Belo Horizonte, MG CEP 30421-169, Brazil. Electronic address: patriciarezende@des.cefetmg.br.
authors: Patrícia Sueli
authors: PS
authors: Rezende
authors: Laboratório de Físico-Química de Produtos de Origem Animal - POA/PL, Laboratório Nacional Agropecuário do Estado de Minas Gerais - LANAGRO/MG, Avenida Rômulo Joviano, s/n, Caixa Postal 35 e 50, Pedro Leopoldo, MG CEP 33600-000, Brazil.
authors: Geraldo Paulo do
authors: GPD
authors: Carmo
authors: Laboratório de Físico-Química de Produtos de Origem Animal - POA/PL, Laboratório Nacional Agropecuário do Estado de Minas Gerais - LANAGRO/MG, Avenida Rômulo Joviano, s/n, Caixa Postal 35 e 50, Pedro Leopoldo, MG CEP 33600-000, Brazil.
authors: Eduardo Gonçalves
authors: EG
authors: Esteves
mesh_terms: D000818:Animals; D002417:Cattle; D019327:Copper Sulfate / Q000737:chemistry*; D003611:Dairy Products / Q000032:analysis*; D005506:Food Contamination / Q000032:analysis*; D007201:Indicator Dilution Techniques; D008892:Milk / Q000737:chemistry*; D011786:Quality Control; D012031:Refractometry / Q000379:methods* / Q000592:standards*; D015203:Reproducibility of Results; D044967:Serum / Q000737:chemistry*
chemical_list: D019327:Copper Sulfate
keywords: Method validation; Milk quality; Refractometry