Analytical grade C-phycocyanin obtained by a single-step purification process

C-phycocyanin (C-PC) is a phycobiliprotein that can be used as a natural blue dye in the food and cosmetic industries, as a biomarker or as an agent in medical treatments, depending on its purity grade. Here we described for the first time a single-step purification process of C-PC extracted from the wet biomass of Spirulina (Arthrospira) platensis LEB-52 using ion exchange chromatography with pH gradient elution. Different conditions varying the elution buffers and volumes, the loading pH and the addition of salt in the elution buffer were studied. The chromatographic condition that resulted in high recovery and purity consisted in equilibration and washing with 0.025 mol/L Tris-HCl buffer pH 6.5 and elution combining a step with 0.08 mol/L NaCl in 0.025 mol/L Tris-HCl buffer pH 6.5 and a pH gradient elution with 0.05 mol/L citrate buffer pH 6.2–3.0. This process resulted in C-PC with purities of 4.2 and 3.5 with recoveries of 32.6 and 49.5 %, respectively, in one purification step.