Experimental methods and operational steps:

Preparation of reagents and materials

Streptomycin detection kit, pure water (first grade water in accordance with GB/T6682)

Preparation of instruments and equipment

DF-3500 food safety detector, 8-channel pipette, single channel pipette, mixing shaker, centrifuge, stoppered test tube, metal bath,

Preparation of samples

Organize a sample of 1000g to remove fat, crush, mix well, and label. Use the quartering method to separate milk and powdered milk into no less than 500g and label. Store at -18 ° C to -20 ° C.

Measurement steps:

The DF-3500 food safety detector selects a wavelength of 450nm, adds the test sample to the microplate, sequentially adds the corresponding reagents, and washes the plate more than 5 times. After measuring the OD value, the final result is calculated.