Measurement of Aldehydes in Low Density Lipoprotein by High Performance Liquid Chromatography

A modified procedure is presented for the HPLC determination of nanomolar concentrations of n-alkanals, hydroxyalkenals, malondialdehyde and furfural in biological fluid. The modifications allow aldehyde profile analysis of small samples of fresh, human, low density lipoprotein (LDL), enabling more detailed studies of LDL fatty acid peroxidation. Aldehydes are reacted with 1,3-cyclohexanedione to produce fluorescent derivatives which are separated by gradient, reversed phase, high performance liquid chromatography (HPLC). Analysis time has been reduced by shortening the sample preparation. Sensitivity has been increased by miniaturization of the derivatisation procedure, reducing required sample size. Recoveries of added aldehydes have been improved. In addition, the method presented allows determination of three further aldehydes, not measured previously by CHD methods: malondialdehyde, formaldehyde and furfural. Recovery and variability data and concentrations of aldehydes found in human LDL are given. The capacity of the method for further development, to enable determination of other aldehydes such as the trans, 2-alkenals, is also demonstrated.