Interlaboratory study of acid orange 12 dye binding for measuring protein in meat

Six samples of beef and pork were analyzed by 4 laboratories, using the dye binding method. Dye binding protein was calculated by using a dye binding capacity of meat of 0.410 mg dye bound/g protein. Correlations of 0.976, 0.987, 0.996, and 0.995 were found between dye binding and Kjeldahl protein values. An analysis of covariance showed that the slopes of regression between dye binding and Kjeldahl protein for 3 laboratories were not significantly different at the 5% level. The adjusted means of the regression lines for the same 3 laboratories were significantly different at the 1% level. The results show that 3 of the laboratories were finding the same relationship between dye binding and Kjeldahl protein but were not in calibration with one another.