Rapeseed methyl ether

For these last reactions, acid catalysis gives a better conversion rate than basic catalysis, which promotes transesterification and the formation of side products. The reaction of epoxidized rapeseed methyl esters with heptanol and PTSA (100°C, 12 h, 1 bar) led to fatty ethers with an oxirane value of 0.0 and a saponification number of 130 methyl heptyloxy-hydroxystearate was the main reaction product. 

Information on the occurrence of alternaria mycotoxins in food and feed is relatively limited. For example altemariol, its methyl ether and tenuazonic acid were frequently detected in apples, apple products, apple juice concentrates, mandarins, ohves, pepper, red pepper, tomatoes, tomato products, oilseed rape meal, sunflower seeds, sorghum, wheat and edible oils (olive oil, rapeseed oil, sesame oil and sunflower oil). The maximum levels reported in foods are... 

In recent years several normal-phase HPLC methods have been reported for the quantitative analysis of tocopherols and tocotrienols (Table 11.5). The best of these methods have been able to achieve baseline separation of all four tocopherols and all four tocotrienols, as shown in Figures 11.2 and 11.3. Kamal-Eldin et al. (2000) reported the optimal baseline separation of all eight common tocols using a Diol-bonded phase column and an isocratic mobile phase of hexane/methyl tert-butyl ether (MTBE), 96 4, v/v (Figure 11.2). Similar separations were reported by Moreau et al. (2007) using the same type of column and mobile phase. Schwartz et al. (2008) reported that, with a normal-phase silica column, plastochromanol-8 in rapeseed oil eluted between y-tocopherol and 5-tocopherol. 

Figure 1.2 High-performance thin-layer chromatogram of methyl esters of fatty acids, showing separation based on unsaturation. The plates were developed in the solvent system hexane/ diethyl ether, 92 8 vol./vol. a = a standard mixture of tetracosaenoic (24 1 vol./vol.) and docosahexaenoic (22 6 vol./vol.) fatty acid methyl esters b = sea scallop lipids c = dogfish liver d = menhaden e = redfish f=rapeseed g = cod liver. Reproduced with permission from Shantha, N. C. and Ackman, R. G., Silica gel thin-layer chromatographic method for concentration of longer-chain polyunsaturated fatty acids from food and marine lipids, Canadian Institute oj Food Science and Technology Journal, 24, 156-60, 1991.

This successful separation of erucic acid was reported to the EEC Committee of Experts in September 1976 as an outline procedure possibly suitable as the basis of an official method. The report proposed that the procedure could be made quantitative by scraping-off the methyl erucate spot, extracting the ester from the powdered silica gel with ether and, after adding methyl tetracosanoate (C24 0) as an internal standard, determining the erucic acid by conventional GLC as in the analysis of rapeseed oil. 

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See also in sourсe #XX -- [ ]

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