After saponification, the lipid extract, called “unsaponifiables”, may contain other lipids besides sterols including hydrocarbons, carotenoids, tocopherols, free fatty acids, and other triterpenes. Many researchers proceed with derivatization and GC analysis without further sample cleanup and do not have problems with interference by these compounds. This is usually acceptable for the unsaponifiables fraction of a refined fat or oil sample. However, in some samples, such as crude oils, it may be necessary to further purify the sterol fraction from polar unsaponifiable lipids. Silica, C18, and aminopropyl SPE cartridges have all been used for this purpose. Phillips and co-workers  used aminopropyl SPE columns to separate sterols and stanols from serum unsaponifiable lipids, using chloroform: isopropanol for elution. Toivo and co-workers  demonstrated that equal yields were obtained using either C18 or silica SPE columns and eluting the sterol fraction from either column with 5% methanol in chloroform or 1% isopropanol in hexane, respectively.
This application note describes the extraction of cocaine and major metabolites from whole blood, prior to GC/MS analysis. This protocol also allows the simultaneous extraction of various other drugs of abuse classes: amphetamines, barbiturates, benzodiazepines and opiates.
ISOLUTE® SLE+ columns with 1 mL sample capacity are used to extract whole blood samples following a straightforward sample dilution. No protein precipitation or other pre-treatment is required prior to sample loading. The sample preparation procedure delivers clean extracts, good recoveries and RSD values and LLOQs from 20 ng/mL (analyte dependant).
Tags: Anhydroecgonine Methyl Ester AEME , Anhydroecgonine methyl ester , Application Notes , Benzoylecgonine , Clinical , Cocaethylene , Cocaine , Cocaines , Column , Drugs of Abuse , Ecgonine Methyl Ester EME , English , Forensic , GC-MS , Whole blood
Selecting an HPLC Column: The heart of a HPLC system is the column. Changing a column will have the greatest effect on the resolution of analytes during method development. Choosing the best column for application requires consideration of stationary phase chemistry, retention capacity, particle size, and column dimensions. The three main components of an HPLC column are the hardware (column housing), the matrix, and the stationary phase. Generally, modern reverse phase HPLC columns are made by packing the column housing with spherical silica gel beads which are coated with the hydrophobic stationary phase.