High-performance liquid chromatographic determination of some polar phospholipids in serum

High-performance liquid chromatography method for quantifying sphingomyelin in rat brain

A rapid, reproducible and accurate high-performance liquid chromatographic (HPLC) method for the quantitative determination of sphingomyelin in rat brain was developed and validated using normal-phase silica gel column, acetonitrile-methanol-water (65:18:17 (v/v)) at a flow rate of 1 ml/min, isocratic elution, UV detection at 207 nm and 1,2-dimyristoyl-sn-glycero-3-phosphocholine as an internal standard. Total run time was 10.0 min. The calibration curve was linear over the range of 0.025-0.4 mg/ml sphingomyelin (R2>0.99). The intra-day coefficient of variation ranged from 1.4% to 2.2%. The average inter-day coefficient of variation over a period of 4 days was 3.1%. The practical limit of detection was 0.005 mg/ml with a quantification limit of 0.01 mg/ml.

High-performance liquid chromatographic determination of cholesteryl esters in the blood of obese children

The serum of obese children and adolescents was analyzed for cholesteryl esters. The test substances were first separated from the sample matrix by solvent extraction and thin-layer chromatography and then resolved in a reversed-phase high-performance liquid chromatographic system involving a Separon SGX C18 column and a mobile phase of 2-propanol-acetonitrile (40:60, v/v), with ultraviolet detection at 206 nm. Cholesterol and 10-cholesteryl esters could be separated and determined within ca. 25 min at a flow-rate of 1 ml/min. The method was applied to a study of the effect of external conditions (physical stress, diet) on the content of cholesteryl esters in a test group of obese boys and girls aged from 13 to 16 years. The analyses have demonstrated that the above conditions do not affect the concentrations of the individual cholesteryl esters, although the total cholesterol concentration decreased significantly after spa treatment.

Isolation and purification of lecithin by preparative high-performance liquid chromatography

Mixed-chain, multispecies, egg yolk-derived lecithin was isolated and purified on a silica column with isocratic elution. A method development column (20 x 0.46 cm I.D.) packed with YMC 15-30 microns, 120 A spherical silica and a mobile phase consisting of 5 mM ammonium acetate in acetonitrile-2-propanol-methanol-water (80:13:5:12) was used to separate the lecithin from other phospholipids. The mobile phase conditions for the method development system was adopted for two types of preparative HPLC systems: a Separations Technology SepTech NovaPrep 5000 system with a 20 x 1.93 cm I.D. column and a ST/800A system with a 20 x 5.00 cm I.D. Annular Expansion (A/E) column. The maximum load was 50 microliters of crude solution (2 mg) for the method development column, 0.90 ml (35 mg) for the 20 x 1.93 cm I.D. column and 6.0 ml (240 mg) for the 20 x 5.00 cm I.D. A/E column. The flow-rates were 2, 35 and 235 ml/min, respectively. The fractions collected from the preparative systems were analyzed for purity by analytical-scale high-performance liquid chromatography and by thin-layer chromatography with selective detection with molybdenum blue for phospholipids and detection of all organic compounds by sulfuric acid. Purity of the recovered lecithin was greater than 99%.