Gas chromatographic determination of high molecular weight alcohols from policosanol in omega-3 fish oil by acylation with acetyl chloride.

A new validated gas chromatographic (GC) method using acetyl chloride as a derivatizing agent for determining policosanol's high molecular weight alcohols (policosanol's fatty alcohols; PFAs) in fish oil (FO) is described. Before derivatizing the alcohols, FO was subjected to a methylation reaction, and then the PFAs were isolated in a chloroform fraction by silica gel by column liquid chromatography. GC analysis was performed using a BPX-5 wide-bore column and 1-eicosanol as an internal standard. Validation assays applied to the method proved noninterference by a very complex mixture of the FO with PFAs, even for samples subjected to stress conditions. Good linearity [correlation coefficient >0.999, relative standard deviation (RSD) of the slope <1.3%, and RSD of the response factors <1.9% with no bias] and accuracy (average recovery from 100.6 to 102.2%) over a range of 28-142% of the nominal concentration were obtained. Within-day and intermediate precisions at the nominal dose (100%) were 1.7 and 2.9%, respectively. The method was successfully used to identify and quantitate the PFAs in FO.