Vitamins chloroform application

The title compound 188, currently under development for the treatment of acne, psoriasis and photoaging via a topical application, has been synthesized161 in two steps by reacting carboxyl-[14C]vitamin A, 189, with ethyl chloroformate and subsequent treatment of the mixed anhydride 190 with acetamidophenol in the presence of a catalytic amount of 4-dimethylaminopyridine (equation 68), Carbon- 14-labelled compound was needed to investigate its metabolism and the extent of systematic adsorption of 188 after dermal application. 

Modern LSD detectors yield good results even under gradient elution. No disturbance is observed when solvent composition changes. Organic solvents (acetone, propanol, chloroform) can be used in the mobile phase. In reversed-phase mode, water content up to 25% and small amounts of buffers are not a problem. Typical applications are lipids, phospholipids, sugars, and vitamins. 

Chloroform (trichloromethane, CHClj). Chloroform was first used as an anaesthetic in 1847 and its narcotic effects on the central nervous are well documented (ref. 4la). It has important applications as an intermediate in the chemical synthesis of a large number of industrial chemicals chlorofluorocarbons, dyes, drugs and pesticides. Its powerful solvent properties and low boiling point (6l°C) have made it a favorite for extractive and purification operations in preparing antibiotics, alkaloids, flavors and vitamins. 

A few applications of sterol TLC in practice may be added Determination of dihydrocbolesterol in serum [192] of sterols and vitamin D in cod liver oil [193] of aracMdonates [petrol ether-benzene (60 + 40)] [116] and other synthetic sterols (diisopropyl ether, benzene) [170] and of sitosteryl esters [cyclohexane-benzene mixtures, chloroform-acetone (95 + 5), heptane-ethyl acetate (95 + 5), carbon tetrachloride-chloroform (95 + 5)] [18] separations of unsaturated plant sterols from the corresponding hydrogenated compoimds, using the bromine-system (separation of 3j8,5a-stanols from the zj ,3 -sterols) [91] and of skin sterols [88] and milk sterols and their esters [117]. Pfeifer [137] has studied sterol separations on micro plates and their densitometric evaluation. 

Nondestructive detection of K vitamins can be performed either by elution of separated bonds (localized by a standard spot) with chloroform and following determination of K vitamin concentration by UV detection (53) or mass selective detection (54,58). Densitometric scanning of TLC plates, based on either absorption, fluorescence, or fluorescence quenching of coated plates (55), is another method for nondestructive detection and can be used with external as well as internal standardization. The introduction of this quantitation method resulted in an improvement in terms of speed, sensitivity, and precision of TLC but could not prevent the advance of HPLC applications in past decades. 

---