Storage of Lipid Extracts

Autoxidation is always a concern for storage of lipid extracts. They should not be stored in a dry state, but dissolved in a small volume of a relatively nonpolar (aprotic) solvent. The lipid samples should be stored at -20 C at least in a glass (never plastic) container. Air should be excluded from the container by flushing with a stream of nitrogen. Antioxidants should be used for prolonged storage. 

Christie, W.W. and Han, X. (2010) Lipid Analysis Isolation, Separation, Identification and Lipidomic Analysis. The Oily Press, Bridgwater, England, pp 448. 

Holtzman, D.M. and McKeel, D.W., Jr. (2001) Plasmalogen deficiency in early Alzheimer s disease subjects and in animal models Molecnlar characterization nsing electrospray ionization mass spectrometry. J. Neurochem. 77, 1168-1180. 

(2010) Multi-dimensional mass spectrometry-based shotgun lipidomics and the altered lipids at the mild cognitive impairment stage of Alzheimer s disease. Biochim. Biophys. Acta 1801, 774-783. 

and Han, X. (2009) Automated hpid identification and quantification by multi-dimensional mass spectrometry-based shotgun lipidomics. Anal. Chem. 81,4356-4368. 

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The general rules that should therefore be observed include the use of a blanket of nitrogen whenever possible and evaporation of solvents at the lowest feasible temperatures, which must not exceed 50°C. The addition of an antioxidant such as butylated hydroxytoluene (2,6-di-/-butyl-4-methylphenol) to the extraction solvents (0.1 g 1 ) might be necessary to prevent deterioration of unsaturated lipids but it is essential for storage of lipid extracts at about 0.1% of the weight of lipid. Inactivation of lipolytic enzymes may usually be achieved by addition of an alcohol such as methanol or, in some cases, isopropanol. The latter is recommended for some more stable enzymes sometimes found in plant tissues. Alternatively the plant may be briefly immersed in boiling water. 

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