Abstract: Based on the two-dimensional correlation mid infrared spectroscopy, a rapid method for the identification of tetracycline in milk was established. 20 pure milk samples and 20 tetracycline adulterated milk samples（0.005~30 mg/L）were prepared respectively. At room temperature, the conventional one-dimensional spectral data of milk samples were collected in the range of 400~4 000 cm^-1. Taking the concentration of tetracycline in milk as the external perturbation, synchronous and asynchronous two-dimensional correlation spectra were constructed in the range of 1 500~1 700 cm^-1 and 3 250~3 450 cm^-1, respectively. The absorption peaks at 1 550 cm^-1 and 1 640 cm^-1 were supposed to come from the tetracycline in milk, which were caused by the stretching vibration of C==N and C==O bonds. At 3 310 cm^-1, the peak also came from tetracycline, which was caused by the stretching and bending vibration of N––H bond. The results showed that the analysis of two-dimensional correlation mid infrared spectral characteristics can qualitatively determine whether the milk is adulterated with tetracycline.

Key words: milk, tetracycline, mid infrared spectroscopy, two-dimensional correlation