Potential Sources of Copper Contamination of Farm Milk Supplies Measured by Atomic Absorption Spectrophotometry

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Abstract
A method was developed to use atomic absorption spectrophotometry for copper measurements in milk filtrates prepared from equal volumes of milk and 20% trichloracetic acid. Results are reported for 11 farms for water supplies, wash and rinse solutions, and milk. Copper below 10 mug/liter was found at the well for the 5 farms with their own spring supply. Averages and ranges for all 11 farms in mug/liter were 33 (0 to 156) at the cold water tap in the milk house, 220 (8 to 1,360) at the hot water tap, 246 (8 to 1,722) in the wash sink with added detergent and hot water, and 275 (9 to 1,823) after using the wash solution. Rinse solution with hypochlorite in cold water showed a rise from 31 (1 to 157) before use to 51 (5 to 206) after use. Copper in milk averaged 99 mug/liter (72 to 163). In spite of relatively high copper in wash solutions, copper in milk was not correlated postively, giving rise to question whether adsorbed copper from such solutions can contribute much copper to milk. Thorough rinsing with low copper cold water and a high dilution ratio in milk were seen as mitigating factors. Direct contact of milk with copper bearing metals presented a greater opportunity for contamination. Removal of substantial amounts of copper from pipe lines and bulk tanks with sulfamic acid was demonstrated.

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