Intralipid as Matrix Additive for Evaluating Hyperlipidemic Postmortem Blood.

INTRODUCTION: Postmortem whole blood samples can differ greatly in quality where hyperlipemia is a frequent variable that can influence the results of analytical methods. The aim of this study was to investigate the influence of lipemia on postmortem analysis as well as to demonstrate the usage of Intralipid in comparison to pooled postmortem lipids as matrix additives for meaningful evaluation and validation of hyperlipidemic postmortem samples.

METHODS: Hyperlipidemic blood samples were simulated by adding different concentrations of Intralipid® or pooled authentic postmortem lipids to bovine whole blood. The hyperlipidemic blood samples were spiked with 14 benzodiazepines, and five sedative and antianxiety drugs (alprazolam, clonazepam, 7-aminoclonazepam, diazepam, flunitrazepam, 7-aminoflunitrazepam, hydroxyzine, lorazepam, midazolam, nitrazepam, 7-aminonitrazepam, nordazepam, oxazepam, propiomazine, dihydropropiomazine, temazepam, triazolam, zolpidem and zopiclone,). Samples were prepared with LLE followed by UHPLC-MS/MS. The effect of lipemia on the recovery of analytes and internal standards were evaluated to determine the effect of, and any differences between, the two additives.

RESULTS: Lipemia was found to cause major interference when quantifying the analytes. For most analytes, the internal standards (IS) could compensate for analyte losses. However, the most hydrophilic analytes (7-amino-metabolites), together with the most lipophilic (propiomazine and dihydropropiomazine), were greatly affected by lipemia (<50% recovery) and the IS could not compensate for analyte losses. In general, lower analyte recoveries were observed for samples with Intralipid as a lipemic additive in comparison to those containing pooled postmortem lipids.

CONCLUSION: Both Intralipid and pooled postmortem lipids showed marked effects on the analytical results. Intralipid gave a good indication of the effects of lipemia and could be a useful tool for making meaningful evaluation of hyperlipidemic postmortem samples during method development and validation.