The chance of a no color change occurring because of contamination with disinfectants or cleaning agents is only possible in case of high concentrations. When such agents are correctly used for disinfection and or cleaning of milking equipment or teat disinfection, the final concentration in the milk is too low to interfere with the test performance.
However, at incorrect use in general, Delvotest® microbial inhibition tests can be inhibited by such compounds. See table below.
Preservatives, used to preserve milk for later analysis, could make the milk unsuitable for testing or will significantly prolong the required incubation time.
Indicative concentration of example disinfectants and cleaning agents giving a positive Delvotest® result at control time (1 ppm = 1000 ppb = 1000 μg/Kg)
Active chlorine | 200 ppm |
Iodine | 150 ppm |
Hydrogen peroxide (30%) | 600 ppm |
Quaternary Ammonium Compounds | 30 – 10000 ppm |
Mercuric chloride (corrosive sublimate) | 10 ppm |
Potasium dichromate | 20 ppm |
Sodium Azide | 50 ppm |