This paper reports effects of concentration of milk, concentration of individual ingredients of detergents, and temperature on transmittance of light at 527 nm through solutions of milk, water, and individual detergent ingredients. Milk in soft water caused the major portion of the variation, more than 99% of the total sum of squares, for each ingredient except sodium hydroxide and wetting agent. Milk contributed 95.7 and 17.9% to the sums of squares for the sodium hydroxide and wetting agent, respectively. Concentration of detergent ingredient and temperature were of practical significance only with wetting agent. Effects of milk on transmittance were significantly different among milk concentrations for all detergent ingredients, except trisodium phosphate in hard water at the lowest concentrations of milk.

Although precipitates contributed to turbidity of solutions containing trisodium phosphate in hard water, milk was responsible for 95.9% of the variance in the sum of squares. Additionally, in hard water milk accounted for 98.9, 99.1 and 99.7% of the sums of squares in analyses of effects on turbidity of sodium tripolyphosphate, sodium hexametaphosphate, and tetrasodium pyrophosphate, respectively. Turbidity increased with time of holding some phosphate solutions, however, this did not appear to pose serious problems in measuring content of milk.

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Author notes

1Contribution from the University of Missouri Experiment Station. Journal Series No. 6924. Approved by the Director. Trade names and names of commercial companies are used in this publication solely to provide specific information. Mention of a trade name or manufacturer does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture or an endorsement by the Department over other products not mentioned.