FAQ: “More customers are asking us about Chinese Pharmacopeia Numbers… is this similar to EP/USP Color?
There are 5 visual pharmacopoeia liquid color standards in use worldwide. All are in the yellow region of color 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 Color Scale for grading pharmaceutical solutions is prepared initially from 3 standard color solutions of cuprous chloride, potassium dichromate and cupric sulfate that are further mixed into 5 stock reference solutions representing 5 color series. Each reference solution is further diluted in concentration to form 10 liquid color 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 Color
The visual CP – Chinese Pharmacopoeia color scale is most similar to EP – European Pharmacopeia Color 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 Color in that the color standard names along each hue line (ex: Y1, Y2….Y10) increase with chroma rather than decrease as EP Color does.
The liquid CP Color standards are different in formulation from EP Color standards in that potassium dichromate is used instead of iron as one of the major color components. There are 50 liquid CP color standards instead of 39 for EP Color.
Industrial Test Methods referencing CP – Chinese Pharmacopoeia Color
CP – Chinese Pharmacopoeia Appendix IX A