Ethanol absolute Phenobarbital

Fusari and coworkers3 have developed a similar method for the assay of phenytoin and phenobarbital in dosage forms. They have used Silanized Celite 545 as the support material, 25% amyl alcohol in chloroform as the stationary phase and 0.05M borate buffer of pH 9.5 as the mobile phase. Phenobarbital was eluted with the mobile phase and phenytoin eluted with absolute ethanol. Ultraviolet absorption was used to quantitate the substances. 

Phenobarbital is prepared by treating benzyl ehloride with sodium eyanide when benzyl eyanide (or a-phenyl acetonitrile) is formed with the elimination of a moleeule of sodium chloride. Benzyl cyanide, first on hydrolysis yields phenyl aeetic acid which on subsequent esterification with ethanol forms the eorresponding ester as ethyl phenyl acetate. This on reaction with diethyl oxalate in the persence of absolute ethanol and sodium metal gives diethyl phenyl oxalo acetate which on distillation at 180°C results into phenyl malonic ester. When it is treated with ethyl bromide and sodium ethoxide, the lonely active hydrogen atom gets replaced with an ethyl group thus forming ethyl phenyl malonic ester. Lastly, this on condensation with urea loses two molecules of ethanol and finally forms the desired compound phenobarbital. 

Pippenger and Gillen (32) determined primidone, phenobarbital, phenylethylmalondiamide, and a number of other amticonvulsants in plasma, urine, and cerebrospinal fluid. They extracted the sample with chloroform after buffering to pH 6.8. The chloroform extract was evaporated to dryness and the residue dissolved in a small amount of absolute ethanol for injection. Recoveries of known amounts of drugs added to the body fluids were 90 to 100 percent. 

In another application of MIPs, Peng et al. devised a biomimetic bulk acoustic wave (BAW) sensor based on ab MIP as a non-aqueous assay for phenobarbital. The MIP, which was based on phenobarbital template and methacrylic functional monomer, was prepared through a noncovalent method, and the resulting sensor was found to work selectively and sensitively in absolute ethanol (linearity range of the response was in the range of 9.0 X 10" M and 5.0 X 10" M and a detection limit of 5.0 x 10" M was observed [452]. 

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