Separation of fatty acids

Separation applications Separation cell Separation, liquid-liquid Separation, low energy Separation, magnetic Separation nozzle Separation of fatty acids Separations... 

Separation of Fatty Acids. Tall oil is a by-product of the pulp and paper manufacturiag process and contains a spectmm of fatty acids, such as palmitic, stearic, oleic, and linoleic acids, and rosia acids, such as abietic acid. The conventional refining process to recover these fatty acids iavolves iatensive distillation under vacuum. This process does not yield high purity fatty acids, and moreover, a significant degradation of fatty acids occurs because of the high process temperatures. These fatty and rosia acids can be separated usiag a UOP Sorbex process (93—99) (Tables 8 and 9). 

Table 8. UOP Sorbex Separation of Fatty Acids from Rosin Acids in Distilled Tall Oil...

Considering their heat sensitivity, the separation of fatty acids and rosin with minimal degradation by fractional distillation under vacuum and/or in the presence of steam is surprisingly good (3). Tad od rosin (TOR) contains about 2% fatty acid and smad amounts of neutrals. Tad od fatty acid (TOFA) contains as Htde as 1.2% rosin and 1.7% neutrals. In typical U.S. TOFA, 49% of the fatty acids is oleic, 45% linoleic, and 3% palmitic, stearic, and eicosatrienoic acid. TOR and TOFA are upgraded to resins and chemicals for the manufacture of inks (qv), adhesives (qv), coatings (qv), and lubricants (see Lubrication AND lubricants). 

Although fatty acids are both oxidized to acetyl-CoA and synthesized from acetyl-CoA, fatty acid oxidation is not the simple reverse of fatty acid biosynthesis but an entirely different process taking place in a separate compartment of the cell. The separation of fatty acid oxidation in mitochondria from biosynthesis in the cytosol allows each process to be individually controlled and integrated with tissue requirements. Each step in fatty acid oxidation involves acyl-CoA derivatives catalyzed by separate enzymes, utihzes NAD and FAD as coenzymes, and generates ATP. It is an aerobic process, requiring the presence of oxygen. 

Separation of fatty acids (Ruthven, 1997). Tall oil from the pulp and paper industry is subjected to separation of rosin acid, linoleic acid, oleic acid, and neutral compounds. Distillation at reduced pressure is u.sed, but this leads to degradation of products. A Sorbex process eliminates this problem. 

PTLC was also used for the separation of lipid components in pathogenic bacteria. Mycobacterium avium has a requirement for fatty acids, which can be fulfilled by palmitic or oleic acid, and these fatty acids are then incorporated into triagylglycerols [80]. PTLC was used for the separation of fatty acids and triacylglycerols in the extracts of these bacterial cells to study the lipid classes in the bacterial cells cultured under different growth conditions. 

Rezanka, T. (1996). Two-dimensional separation of fatty acids by thin-layer chromatography on urea and silver nitrate silica gel plates. J. Chromatogr. A 727(1), 147-152. 

Trathnigg, B., Rappel, C., Rami, R., Gorbunov, A. (2002b). Liquid exclusion-adsorption chromatography a new technique for isocratic separation of non-ionic surfactants V. Two-dimensional separation of fatty acid polyglycol ethers. J. Chromatogr. A 953(1-2), 89-99. 

Figure 21 shows the LC-MS separation of fatty acid lubricants detected using positive ESI with specific ion monitoring as (M—H). The following conditions were employed. 

Theoretically, any number of solutes can be separated in this manner and the method has been applied, for example, to the separation of fatty acids, amino acids, polypeptides and other biological materials with distribution... 

FIGURE 2.10 Demonstration of shape influence on solute retention. Separation of fatty acid esters of identical chain length hut different position of double bonds. Column Prontosil SH 150x4mm mobile phase acetonitrile-water 9-1, v-v. Samples co3-docosa hexaenic acid ethylester (DHAEE) o)3-docosa pentaenic acid ethylester (DPAEE) o)6-docosa pentaenic acid ethylester. 

A) Separation of fatty acid methyl esters derived from almond oil on a BPX-5 column (12 m X 0.25 mm i.d. x 0.25 pm film). Programmed 100° (1 min) then 107min to 320°. The major peaks are shown as offscale so that the minor peaks can be seen clearly. (B) The same sample separated on a HP Stabiliwax column (15 m X 0.25 mm x 0.5 pm film). Programmed 140°... 

Brunner et al [1, 2] investigated separations of fatty acids according to chain length, using methyl esters of different carbon chain length from C14 to Cl8, separation of tocopherols from a by-product of the edible oil production and separation of fish oil esters [3], Stahl et al [4] proposed the supercritical fractionation of orange peel oil and Reverchon et al [5,6] of an orange flower concrete. Different authors treated citrus peel oil [7,8] and citrus oil [9-12]. 

Figure 9.6 Separation of fatty acid methyl esters on a 1.8 m x 4 mm i.d. glass column packed with 10% Silar 10 C on 100/120 mesh Gas Chrom Q. Column temperature programmed from 180° to 200°C at l°C/min. Detector flame ionization at 2 x 10— AFS. Detector temperature 250°C. Injection temperature 250°C.

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. 

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... 

The mobile phases usually used for HPLC separation of fatty acid derivatives are acetonitrile-water, methanol-water, and acetonitrile-methanol-water. Elution with methanol-water mobile phase only failed to resolve linolenic (18 3) and myristic (14 0) acids. 

Whereas in acetonitrile the number of double bonds seems to be more important for solubility, in methanol the chain length seems more important. Utilization of the different properties of these two solvents offers some possibility for the separation of fatty acids whose differences in chain length and degree of unsaturation may make them difficult to separate with the use of either acetonitrile or methanol alone. 

Fig. 10 Separation of fatty acids as their methylmethoxycoumarin esters flow rate, 0.5 ml /min room temperature fluorescence detection (excitation 325 nm, cutoff filter, 398 nm) eluent acetonitrile/water (80 20 v/v) to 100% acetonitrile in45 min. Peaks A. C14.0 + C16 1 B. 06 0 C. 07 0 D. 08 0 E. 08 1 G. C20 4 1. unknown.

Some work has been done to perform the separation of fatty acids. The first results were published by Szepy52 and were associated with the separation of C16 to C22 methyl esters. An interesting patent has been granted to Pronova53 which associates classical (batch) chromatography with an SMB with two inlets to obtain pure EPA(C2o) and pure DHA(C22) from... 

More recently, capillary or open tubular columns have in part replaced packed columns in GLC analysis because of their high efficiency (100000 theoretical plates overall) and their high resolving power. A number of methods for the separation of fatty acid methyl-esters have been reviewed (Christie, 1982a). 

Theoretically, any number of solutes can be separated in this manner and the method has been applied, for example, to the separation of fatty acids, amino acids, polypeptides and other biological materials with distribution ratios in some cases differing by less than 0.1. However, the procedure can be lengthy and consumes large volumes of solvents. It is frequently more convenient to use one of the chromatographic techniques described later in this chapter. These can be considered as a development of the principle of countercurrent distribution. 

Polyesters. A large number of polyester phases have been used, particularly for the separation of fatty acid esters. These phases include neopentyl glycol... 

Figure 1-4. Separation of fatty acids on pellicnlar graphitized carbon black from the mixture of ethanol and lO M aqueous NaOH. Refractive index detection. (Reprinted from reference 13, with permission.)...

The first separation on a chemically modihed surface with an aqueous eluent, which later got the name reversed-phase, was also invented by Horvath Figure 1-4, he demonstrated the hrst reversed-phase separation of fatty acids on pellicular glass beads covered with graphitized carbon black. 

Molecular sieve adsorbents have been widely studied and employed to separate saturated, mono- and di-saturated fatty acids or to concentrate them in a mixture. Logan and Underwood (32) patented a method to use zeolite as the adsorbent to separate esters of fatty acids according to their degree of unsaturation. Use of nonionic, hydrophobic cross-linked polymers has also been successful in selective separation of fatty acids (33). The fatty acids are first allowed to adsorb onto the solid bed of a particular adsorbent and then the adsorbed acids may be desorbed by employing a suitable desorbent. 

The choice of solvent for chromatographic separation of fatty acid esters depends on the desired purity of the eluted fractions and their end use as well as production requirements. Tetrahydrofuran/methanol/water (25 55 20, v/v/v) (41) and methanol/ water (90 10, v/v) (42) have been described to yield EPA and DHA with high purity (75-96%) as fatty acid ethyl esters from fish oil. Krzynowek et al. (43) obtained higher purity fractions of EPA and DHA using the tetrahydrofuran (THE) system of Tokiwa et al. (41). However, THE oxidizes readily yielding peroxides that initiate oxidative decomposition of PUEA and is potentially explosive. Ethanol and water would be the solvents of choice if the end product is to be consumed by humans. 

Both handmade and precoated plates provide reliable separation of fatty acids. Successful separation of triacylglycerols has been achieved on handmade plates only. 

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