Lipids of commercial serum products offered as controls or "standards" for cholesterol and triglyceride determinations.

The cholesterol and triglyceride content of commercial control products (usually sera), purchased from six manufacturers, were measured. In addition, total fatty acid and qualitative neutral lipid composition of the total lipids were measured by gas-liquid and thin-layer chromatography, respectively. Cholesterol values we found by the Abell-Kendall method differed from the values given for six of the 12 assayed products by 6 to 37 mg/100 ml; triglyceride values, determined by a modified Carison procedure, differed from the means given for two of the four assayed products by 14to 17 mg/lOU ml. Neutral lipids present in total lipids in 13of 15 lyophilized samples, and fatty acid composition of the latter in 12, closely resembled those of freshly drawn human serum, indicating that the lipids had not deteriorated grossly. The lipids of one lyophilized product from a bovine serum source included an appreciable amount of linolenic acid, which is not found in human serum; a second contained an unknown lipid-solvent material. Some decomposition of the lipids was noted in a filtered liquid sample. These results strongly support the use of commercial lyophilized preparations as control sera, but not as secondary serum standards.