title: Gravimetric determination of phospholipid concentration.
abstract: Accurate determination of lipid concentrations is an obligatory routine in a research laboratory engaged in studies using this class of biomaterials. For phospholipids, this is frequently accomplished using the phosphate assay (Bartlett, G.R. Phosphorus Assay in Column Chromatography. J. Biol. Chem. 234, 466-468, 1959). Given the purity of the currently commercially available synthetic and isolated natural lipids, we have observed that determination of the dry weight of lipid stock solutions provides the fastest, most accurate, and generic method to assay their concentrations. The protocol described here takes advantage of the high resolution and accuracy obtained by modern weighing technology. We assayed by this technique the concentrations of a number of phosphatidylcholine samples, with different degrees of acyl chain saturation and length, and in different organic solvents. The results were compared with those from Bartlett assay, (31)P NMR, and Langmuir compression isotherms. The data obtained show that the gravimetric assay yields lipid concentrations with a resolution similar or better than obtained by the other techniques.
authors: Helsinki Biophysics and Biomembrane Group, Department of Biomedical Engineering and Computational Science, School of Sciences, Aalto University, P.O. Box 12200, FI-00076 Espoo, Finland.
authors: Roberto
authors: R
authors: Tejera-Garcia
authors: Lisa
authors: L
authors: Connell
authors: Walter A
authors: WA
authors: Shaw
authors: Paavo K J
authors: PK
authors: Kinnunen
mesh_terms: D009682:Magnetic Resonance Spectroscopy; D010713:Phosphatidylcholines / Q000737:chemistry; D010743:Phospholipids / Q000032:analysis*; D058525:Quartz Crystal Microbalance Techniques; D012997:Solvents / Q000737:chemistry; D013818:Thermogravimetry
chemical_list: D010713:Phosphatidylcholines; D010743:Phospholipids; D012997:Solvents