Retinyl acetate chromatography

Retinyl acetate [127-47-9] M 328.5, m 57". Separated from retinol by column chromatography, then crystd from MeOH. See Kofler and Rubin [Vitamins and Hormones (NY) 18 315 1960] for review of purification methods. Stored in the dark, under N2 or Ar, at 0°. See Vitamin A acetate p. 574 in Chapter 6. 

Retinyl acetate [127-49-9] M 328.5, m 57 . Separated from retinol by column chromatography, then... 

Figure 10.9 Chromatograms of fortified coconut oil obtained by using (a) normal-phase HPLC and (b) GPC/normal-phase HPLC. Peak identification is as follows 1 (a,b), DL-a-toco-pheryl acetate, 2 (b), 2,6-di-terf-butyl-4-methylphenol 2 (a) and 3 (b), retinyl acetate 3 (a) and 4 (b), tocol 4 (a) and 5 (b), ergocalciferol. Reprinted from Analytical Chemistry, 60, J. M. Brown-Thomas et al., Determination of fat-soluble vitamins in oil matrices by multidimensional high-performance liquid chromatography , pp. 1929-1933, copyright 1988, with permission from the American Chemical Society.

Chromatograph the System Suitability Preparation, and measure the peak areas as directed under Procedure. The resolution, R, between the all-trans retinyl acetate and the all-trans retinyl palmitate peaks is not less than 10 (see System Suitability in High-Performance Liquid Chromatography under Chromatography, Appendix IIA), and the relative standard deviation for replicate injections is not more than 3.0%. 

The amount of encapsulated model drug (retinyl acetate or progesterone) per mg of dried LS was determined through solubilization of LS in ethyl acetate at 60°C. Following filtration, the solution was analyzed by reverse-phase high-performance liquid chromatography (HPLC) to find the drug content. 

Guiso, G. Rambaldi, A. Dimitrova, B. Biondi, A. Caccia, S. Determination of orally administered all-trans-retinoic acid in human plasma by high-performemce liquid chromatography. J.Chromatogr.B, 1994, 656, 239—244 [all-trans-retinyl acetate (IS) extracted metabolites, isotretinoin, tretinoin LOD 10 ng/mL pharmacokinetics non-interfering allopurinol, amikacin, aracytin, ceftazidime, ciprofloxacin, doxorubicin, fluconazole, prednisone]... 

Retinol-11,12- H2 of low specific activity has been prepared (Isler et al., 1960) based on the work of Isler et al. (1947) on the synthesis of retinyl acetate. The same sequence of reactions as shown in Fig. 8, with several improvements in technique because of the small scale, was applied by Perry et al. (1982) to the preparation of retinoic acid tritiated at very high specific activity. Pure, recrystallized diol (XXVI) was partially hydrogenated with tritium over Lindlar catalyst in the presence of quinoline and the dihydro compound (XXVII), acety-lated in such a way as to afford mainly the monoacetate (XXVIII). Exposure of the acetate at low temperature for a very short time to very dilute hydrogen bromide in methylene chloride gave, after chromatography, pure retinyl-11,12- H2 acetate (XXIXa). Simultaneous hydrolysis and oxidation of the retinyl acetate by silver oxide in aqueous methanolic sodium hydroxide then yielded all-fran -reti-noic-11,12- H2 acid (Vllh). The specific activities obtained ranged from 25 to 40 Ci/mmol. 

LV). Reduction of LV with lithium aluminum hydride to LVI, acetylation of the terminal hydroxyl group to give LVII, and dehydration gave retinyl acetate (XXIXb), which was purified by preparative thin-layer chromatography (TLC). 

When measuring the level of nonpolar retinoids in blood, a modified method of Thompson et al, (1971) could be used (see also Varma and Beaton, 1972 Bieri et al., 1979 Ross, 1981). Briefly, the plasma or serum (100-200 xl) is mixed with 1 volume of internal standard solution (e.g., retinyl acetate) in ethanol. To the mixture is added 1-4 volumes of hexane the contents are mixed well and then centrifuged. The hexane (upper phase) is carefully removed and used for chromatography or other analyses. For added protection against oxidation, butylated hydroxytoluene (100 xg/ml) can be added to the hexane. Other solvents used for extraction of retinol and its esters from serum include chlo-roform methanol (see, for example, DeRuyter and De Leenheer, 1978) and hexane methylene chlorideiisopropanol (Besner /., 1980). Recoveries, when reported, range near 100%. 

Finally, a rather unusual technique was developed in Japan (25) for the identification of several drugs in pharmaceutical preparations. The technique is called thin-layer slick chromatography (TLSC) and is described as an advanced version of thin-layer chromatography in a cylindrical form. The adsorbent on the stick is a mixture of silica gel, microciystalline cellulose (proportions, 5 2) and 3% of a binder, hydroxyethylcellulose. One to ten microliters of the sample are spotted on the thin-layer stick 2 cm from the lower end and similarly, standard samples are applied on the reverse side, to ensure precise detection. For the identification of retinyl palmitate or retinyl acetate, pure benzene (200 pi) was used as developer. 

Retinyl palmitate [79-81-2] M 524.9, e m (all-trans) 1000 (325 nm) in EtOH. Separate from retinol by column chromatography on water-deactivated alumina with hexane containing a very small percentage of acetone. Also chromatographed on TLC silica gel G, using pet ether/isopropyl ether/acetic acid/water (180 20 2 5) or pet ether/acetonitrile/acetic acid/water (190 10 1 15) to develop the chromatogram. Then recrystd from propylene. 

WO Landen Jr. Application of gel permeation chromatography and nonaqueous reversed-phase chromatography to high performance liquid chromatographic determination of retinyl and a-tocopheryl acetate in infant formulas. J Assoc Off Anal Chem 65 810-816, 1982. 

Fig. 4. Chromatogram of a mixture of retinyl ester standards. Column, Supelcosil LC-8 (5 jLm) mobile phase, acetonitrile water (88 12) from origin to arrow and acetonitrile water (98 2) for rest of chromatography flow rate, 3 ml/min. The esters of retinol are 1, acetate, 2 0 2, laurate, 12 0 3, 7-linolenate, 18 3 4, myristate, 14 0, 5, palmitoleate, 16 1 6, linoleate, 18 2 7, palmitate, 16 0 8, oleate, 18 1 9, stearate, 18 0 10, arachidonate, 20 4. (Reprinted with permission from Ross, 1981.)...

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