Cryptosporidium parvum and Cryptosporidium meleagridis oocysts have been purified from fecal matter, usually from bovine or porcine sources, generally in simple two-layer Nycodenz® gradients [2- 9], although for the partial separation of Type 1 and Type 2 oocysts linear gradients of the same solute have been used [10]. 

Chesnot and Schwartzbrod [11] noted that Nycodenz® gradients were superior to those of Percoll® for oocyst purification, when considering both “recovery and particulate load”. 

The Nycodenz® solutions have been made up either in phosphate-buffered saline [2] or water [6]; there will be a small difference in density between the two types of solvent, but otherwise it is unlikely that the solvent will have any significant effect on the separation.