MilliporeSigma has developed a physical-chemical assay for pluronic. The assay, which is based on analytical chromatography, is used by the company to test all the pluronic batches that it uses for cell culture media production. Physiologic Relevance Interest in primary cell culture is causing a shift in cell culture media preferences, according to Nicol Watson, Ph.D., senior global marketing manager at Thermo Fisher Scientific, which surveys customers annually about such things. "A good indicator," says Dr. Watson, "is that customers are purchasing more chemically defined media as well as newly introduced transfection reagents that are more efficient for difficult-to-transfect cells, but also gentler on them." Interest in primary cells has caused an uptick in Thermo Fisher's custom media business. "Customers are looking for a slightly leaner medium, to which they add various growth factors and substrates," Dr. Watson adds.