Model II - Blue Yellow



Charm Blue Yellow II is a microbial inhibition assay that detects inhibitors, such as antibiotics – the most common inhibitors found in raw milk. The Charm Blue Yellow II has achieved the Charm Gold Standard by establishing a new benchmark in sensitivity by detecting many antimicrobial drugs at or below EU MRLs (Maximum Residue Limits). It is designed for high volume screening of raw commingled and ultra-pasteurized cow milk.

  • Broadest detection for antibiotics and other antimicrobials
  • Detects many drugs at or near EU MRLs
  • Easy: Just add milk and incubate
  • Results in less than 3 hours
  • Ideal for large volume testing


The starting color in the well is blue. Milk is added to the microwell and incubated. Spores germinate and grow, generating acid which is indicated by color change to yellow. If antibiotics are present in the milk, microbial growth is inhibited so that no acid is generated. Thus antibiotic positive samples remain blue.


The Charm Blue Yellow II Test has achieved Gold Standard status. To be considered a Gold Standard, a Charm Test must not only meet, but exceed standards required for sensitivity, accuracy, precision, reproducibility, and ruggedness.

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