Sampling, preserving and storage of samples shall be the same as for Babcock testing with the following exceptions.

(1) Proportionate portions from each shipment of milk shall be added to the composite sample so that the completed composite sample will contain not less than 5 ounces.

(2) When each shipment of milk is tested on a fresh basis, there shall be at least 5 ounces of milk taken for sample.

(3) Potassium dichromate shall be used for composite samples. Other preservatives may only be used if approved by the director of agriculture specifically for this method of testing.