Interlaboratory Validation of Modified Classical Qualitative Methods for Detection of Adulterants in Milk: Starch, Chloride, and Sucrose

Interlaboratory validation procedures were proposed and performed to confirm the effectiveness of modified classical qualitative methods for the detection of adulterants in milk, including starch, chloride, and sucrose, which were previously validated by a single laboratory approach. Raw milk samples that were adulterated with 150 g L−1 of water and 0.0, 0.3, 0.8, and 1.2 g L−1 of starch, 0, 1.5, 2.0, and 2.5 g L−1 of chlorides, and 0.0, 2.4, 3.0, and 3.6 g L−1 of sucrose were sent to 10 collaborators in Brazil that represent the government, food control, food industry, and university affiliations. Reliability rates of 93 to 100, 98 to 100, and 99 to 100 % were obtained for the starch, chlorides, and sucrose methods, respectively. The prediction intervals for the probability of detection proved the sensitivity and selectivity of the methods. Concordance values were greater than 0.85 to starch, 0.98 to chlorides, and 0.99 to sucrose, indicating precision and that the procedures were properly standardized between the collaborators. The estimated detection limits and unreliability regions confirmed the fitness of the modified methods for their respective purposes.