Analysis of lipids

Selected applications of coupled SEE-SEC consider the analysis of tocopherols in plants and oil by-products (65) or the analysis of lipid-soluble vitamins (66) by using a dynamic on-line SEE-SEC coupling, integrated in the SE chromatograph, based on the use of micropacked columns. 

Iodine is such a universal reagent. It was introduced by Mangold [i] as early as 1961 for the analysis of lipids and used again within a year by Bakrett [2] as a nondestructive reagent . 

In addition to blood, certain types of specimens are submitted to the Pediatric laboratory which would not be commonly seen elsewhere. An example of this is sweat for analysis of chloride. The process of obtaining the sweat by iontophoresis usually falls to the personnel of the Laboratory of Neonatology (17). Stool for analysis of lipids and trypsin is more commonly submitted to the Laboratory of Neonatology than to the laboratory which services the adult population. The reason for this is that one is screening for certain intestinal diseases characteristic of infants and newborns which are rare in adults. Such conditions would be celiac disease, cystic fibrosis and others. 

Analysis of lipid metabolism in adipocytes (insulin stimulation of lipogenesis) using a 60... 

Christie, W.W., Lipids their structure and occurrence, in Lipid Analysis, Isolation, Separation, Identification and Structural Analysis of Lipids, Vol. 5, Christie, W.W., Ed., The Oily Press, England, 2003, pp. 3-33. 

Murtola, T., et al., Conformational analysis of lipid molecules by self-organizing maps, /. Chem. Phys., 125, 054707, 2007. 

Kramer, S. D., Hurley, J. A., Abbott, N. J., Begley, D. J., Lipids in blood-brain barrier models in vitro I TLC and HPLC for the analysis of lipid classes and long polyunsaturated fatty adds, submitted. 

G. Chiavari, D. Fabbri and S. Prati, In situ pyrolysis and silylation for analysis of lipid materials used in paint layers, Chromatographia, 53, 311 314 (2001). 

Evershed, R. P. (1990) Preliminary report of the analysis of lipids from samples of skin from seven Dutch bog bodies. Archaeometry 32, 139 153. 

Evershed, R. P., Turner Walker, G., Hedges, R. E. M., Tuross, N. and Leyden, A. (1995) Preliminary results for the analysis of lipids in ancient bone. Journal of Archaeological Science 22, 277 290. 

Passi, S., Rothschildboros, M.C., Fasella, P., Nazzaroporro, M. and Whitehouse, D. (1981) An application of high performance liquid chromatography to analysis of lipids in archaeological samples. Journal of Lipid Research 22, 778 784. 

Mutant or knockout mice defective in specific enzymes involved in lipid synthesis have provided powerful tools for genetic analysis of lipid function in the nervous system. For example, disruption of the genes for ceramide galactosyl transferase or galactosyl ceramide sulfotransferase,... 

Lipid A constitutes the covalently bound lipid component and the least variable component of LPS (25). It anchors LPS to the bacterial cell by hydrophobic and electrostatic forces and mediates or contributes to many of the functions and activities that LPS exerts in prokaryotic and eukaryotic organisms. In the following sections, the primary structure of lipid A of different Gram-negative bacteria is described, together with some of its characteristic biological properties. Furthermore, this article describes some of the principal methods that have been used for the structural analysis of lipid A and discusses their merits and limitations. 

Byrdwell WC. 2001. Atmospheric pressure chemical ionization mass spectrometry for analysis of lipids. Lipids 36 327. 

Barbizhayev, M. A. (2005). Analysis of lipid peroxidation and electron microscopic survey of maturation stages during human cataractogenesis Pharmacokinetic assay of Can-C N-acetylcamosine prodrug lubricant eye drops for cataract prevention. Drugs 6, 345-369. 

Reviews appeared on the following subjects Analysis of lipid hydroperoxides , the difficulties encountered for hydroperoxide analysis in a plasma matrix , post-column derivatization after GLC of lipid hydroperoxides and methods for detection and characterization of hydroperoxy groups in oxidized polyolefins . 

The dry residue is dissolved in EtOH containing AICI3 and 1,10-phenanthroUne (182), an aliquot of fresh solution of KI in EtOH is added, all is incubated in the dark for 15 min at 37 °C and the absorbance is measured at 357 nm (e =4.5 0.2 x 10 M cm ). The LOD is 1.4 (xM, with linearity up to 20 (xM. It is important to avoid contact with air during the incubation, that may oxidize ions, and the presence of water in the system, which reduces the analytical result . HPLC with UVD at 234 nm can be applied in the analysis of lipid hydroperoxides in LDL, using a conjugated diene as internal standard . ... 

Chen, X., and B. R. T. Simoneit, Epicuticular Waxes from Vascular Plants and Particles in the Lower Troposphere Analysis of Lipid Classes by Iatroscan Thin-Layer Chromatography with Flame Ionization Detection, . /. Atmos. Chem., 18, 17-31 (1994). 

To establish unambiguously the length of a hydrocarbon chain or the position of double bonds, mass spectral analysis of lipids or their volatile derivatives is invaluable. The chemical properties of similar lipids (for example, two fatty acids of similar length unsaturated at different positions, or two isoprenoids with different numbers of isoprene units) are very much alike, and their positions of elution from the various chromatographic procedures often do not distinguish between them. When the effluent from a chromatography column is sampled by mass spectrometry, however, the components of a lipid mixture can be simultaneously separated and identified by their unique pattern of fragmentation (Fig. 10-24). 

D. Holme and H. Peck, Analytical Biochemistry, 3rd ed. (1998), Addison Wcslcv Longman (New York), pp. 406-442. Structure, function, and analysis of lipids. 

D Holme and H Peck, Analytical Biochemtstiy, 3rd ed (1998), Addison Wi li Longman (New York), pp 406-442 Structure, function, and analysis of lipids C Matthews, K van Holde, and K Ahern, Biochemistry, 3rd ed (2000), Benjamin/ Cummings (San Francisco), pp 315-357 Lipid structure and function G Patton, S Cann, H Brunengraber, and J. Lowenstein, in Methods in Enzymology, Vol 72, J Lowenstein, Editor (1981), Academic Press (New York), pp 8-20 Separation of fatty acid methyl esters by gas chromatography on capillary columns N Radin, in Methods in Enzymology, Vol 72, J M Lowenstein, Editor (1981), Academic Press (New York), pp 5-7 Extraction of lipids with hexane-isopropanol L Stryer, Biochemistry, 4th ed (1995), W H Freeman (New York), pp 263-270, 603-606 Lipid structure and function... 

Sample preparation is probably the most important step in any analytical procedure. Poor preparation of lipid samples will only yield inferior or questionable results. Some commonly performed sample-preparation procedures for gas-liquid chromatographic (GC) analysis of fatty acids in food samples are introduced in this unit. Since the introduction of gas chromatography in the 1950s, significant progress has been made in fatty acid analysis of lipids however, fatty acid methyl esters (FAMEs) are still the most commonly used fatty acid derivative for routine analysis of food fatty acid composition. 

Thin-layer chromatography (TLC) on silica gel is well known for its separation power for lipids and related compounds. The flame ionization detector (FID) is a universal analytical instrument that offers high sensitivity and linearity for carbon-containing organic compounds. The combination of TLC and FID led to the wide use of the Iatroscan TLC-FID for the analysis of lipid classes. The adoption of the Iatroscan TLC-FID in both academia and industry has generated sufficient data to indicate that TLC-FID is currently one of the most efficient tools for the quantitation of lipids classes (Ackman et al., 1990 Hammond, 1993). 

The Chromarod consists of a straight quartz rod coated with an adsorbing material, usually silica gel, which can be briefly exposed to a hydrogen flame. The sensitivity of the analysis depends primarily upon the proportions of ionizable carbon atoms in the compound being examined. The system is rapid, sensitive, and simple for the analysis of lipid classes. 

A peak is always present at the site of the original spot on the Chromarod when using the Alternate Protocol, especially when analyzing oxidized lipids. This peak can be partly attributed to the oxidation of lipids prior to and during the analysis of lipid classes by TLC-FID. 

Hammond, E.W. 1993. Chromatography for the Analysis of Lipids. CRC Press, Boca Raton, Fla. Indrasena, W.M., Paulson, A.T., Parrish, C.C., and Ackman, R.G. 1991. A comparison of alumina and silica gel Chromarods for the separation and characterization of lipid classes by Iatroscan TLC-FTD../. Planar Chromatogr. 4 182-188. 

Transesterification, fatty acid analysis of lipids, 437, 439 Triacetin, lipase assays, 378 Triacylglycerol acylhydrolase, 371, 375, 378. See also Lipases Triacylglycerols, 432 Tributyrin, lipase assays, 378 Trichloroacetic acid (TCA) solubility index for protein hydrolysis, 152 in TBARS determination, 548-550 Trienes, conjugated, determination of, 515-517, 523-524, 526, 528 Trifluoroacetic acid (TFA), for determination of neutral sugars, 721-722, 724-725, 729-730... 

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