FAQ: “More customers are asking us about Chinese Pharmacopeia Numbers… is this similar to EP/USP Colour?
There are 5 visual pharmacopoeia liquid colour standards in use worldwide. All are in the yellow region of colour space with many similarities and some differences.
- USP – United States Pharmacopeia
- EP – European Pharmacopeia
- CP – Chinese Pharmacopoeia
- BP – British Pharmacopoeia
- JP – Japanese Pharmacopoeia
The Chinese Pharmacopoeia Colour Scale for grading pharmaceutical solutions is prepared initially from 3 standard colour solutions of cuprous chloride, potassium dichromate and cupric sulfate that are further mixed into 5 stock reference solutions representing 5 colour series. Each reference solution is further diluted in concentration to form 10 liquid colour standards along a hue line:
- Yellowish Green (YG1 – YG10)
- Yellow (Y1 – Y10)
- Orange Yellow (OY1 – OY10)
- Orange Red (OR1 – OR10)
- Brownish Red (BR1 – BR10).
Similarities to EP – European Pharmacopeia Colour
The visual CP – Chinese Pharmacopoeia colour scale is most similar to EP – European Pharmacopeia Colour in being arranged in five (5) hue lines that radiate out from distilled water with increasing chroma or saturation. The CP labeling is more rational than EP Colour in that the colour standard names along each hue line (ex: Y1, Y2….Y10) increase with chroma rather than decrease as EP Colour does.
The liquid CP Colour standards are different in formulation from EP Colour standards in that potassium dichromate is used instead of iron as one of the major colour components. There are 50 liquid CP colour standards instead of 39 for EP Colour.
