Miscellaneous in Quantitative Analysis of Lipids

No matter what delivery tool (i.e., HPLC, syringe, or loop injection) is used for analysis of lipids, it is advisable to use a metal needle or a metal-coated capillary as the spray tip instead of a silica capillary tube. The latter is frequently used in proteomics. This is because a high content of certain solvents (e.g., chloroform) is frequently used for lipid analysis, and these solvents can readily damage silica tubing under a high voltage, leading to the loss of ionization stability. 

Currently, a flow rate ranging between hundred nanoliters to a few microliters per minute from an HPLC system can be coupled directly to the ion source chamber. However, a splitter must be utilized if an HPLC system can only deliver at a higher flow rate. To a similar setting, a postsource delivery device could be utilized to introduce a type of particular modifier if this modifier might interfere with the HPLC separation with or without a solvent gradient. 

and Han, X. (2011) A practical approach for determination of mass spectral baselines. J. Am. Soc. Mass Spectrom. 22, 2090-2099. 

Koivusalo, M., Harmi, P., Herkinheimo, L., Kostiainen, R. and Somerharju, P. (2001) Quantitative determination of phospholipid compositions by ESI-MS effects of acyl chain length, unsaturation, and lipid concentration on instrument response. J. Lipid Res. 42, 663-672. 

Sparagna, G.C., Johnson, C.A., McCune, S.A., Moore, R.L. and Murphy, R.C. (2005) Quantitation of cardiohpin molecular species in spontaneously hypertensive heart failure rats using electrospray ionization mass spectrometry. J. Lipid Res. 46,1196-1204. 

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