EP – European Pharmacopoeia Color is a visual liquid color scale used primarily in the pharmaceutical industry. It consists of 3 primary color standard solutions (yellow, red and blue) mixed with hydrochloric acid to make 5 standard color solutions – B (brown), BY (brownish-yellow), Y (yellow), GY (greenish-yellow) and R (red). These 5 standard color solutions are further diluted with hydrochloric acid (10 mg/l) at different concentrations to make 37 reference EP liquid color standards – 9B, 7BY, 7Y, 7GY and 7R, radiating out from distilled water at the center.

Reference for EP European Pharmacopoeia Liquid Color Standards

European Pharmacopoeia Method 2.2.2 Degree of Coloration of Liquids, European Pharmacopoeia, Strasbourg, France (1997: 15-16)  

There are multiple sources for EP Color standards (search on the Internet for “EP European Pharmacopoeia Color Standards”), here are two suppliers that we have experience with.

Sources for EP European Pharmacopoeia Liquid Color Standards

• Fluka Analytical of Sigma-Aldrich, St. Louis, MO 63178 USA (search on “Pharmaceutical Calibration Standards”, then select “Ph Eur Color Standards”).

 The 37 EP Liquid Color Standards from Fluka Analytical come in sets for each of the 5 standard color solutions – B (brown), BY (brownish-yellow), Y (yellow), GY (greenish-yellow) and R (red) and comes in sets of 2 ml and 10 ml volumes

• RICCA Chemical, Arlington, TX 76094 USA

Note: that RICCA Chemical EP color standards are ordered through Fisher Scientific (fischersci.com; search on “EP Colorimetric Standards”).

RICCA Chemical can supply the 3 primary color standard solutions (yellow, red and blue), or the 5 standard color solutions – B (brown), BY (brownish-yellow), Y (yellow), GY (greenish-yellow) and R (red) in quantity to mix into the 37 individual EP liquid color standards. They can also make up any of the 37 individual EP liquid color standards and certify them.