A rapid sample preparation method for the analysis of stable isotope ratios of beef from different countries.

RATIONALE: The use of multi-isotopic analyses to trace beef is gaining wider acceptance, but there is still no uniform standard pretreatment method for stable isotope ratio determinations. Drying and defatting of meat samples are usually applied. Thus, a rapid sample preparation prrocedure is needed to provide a reference for the study of beef by stable isotope methods. METHODS: A student's t-test (T-test) was used to determine significant differences between delta(13) C and delta(15) N values in traditional and rapid beef preparation. The delta(13) C, delta(15) N, delta(2) H, and delta(18) O values of beef samples from six countries were assayed by elemental analyzer-isotope ratio mass spectrometry (EA-IRMS). Stable isotope data were subjected to principal component analysis (PCA), discriminant analysis (DA), and partial least square-discriminant analysis (PLS-DA). RESULTS: There was no significant difference (P > 0.05) between the delta(13) C and delta(15) N values between the two preparation approaches. A classification of satisfactory was obtained with the original-validation rate of 96.6% and the cross-validation rate of 95.9%. The PLS-DA model was correctly validated to differentiate the beef from six countries. CONCLUSIONS: We describe a rapid sample preparation method for beef samples. A model combining stable isotope data and chemometric methods correctly assigned the origin of beef from different countries. The results demonstrated the successful utilization of rapid pretreatment methods to prepare beef samples when using multiple stable isotope analyses to trace beef from different countries.