Hydroquinone liquid chromatography

High pressure liquid chromatography (HPLC) was used for the quantitative measurement of quinones and hydroquinones in the cultures. 20 pi of supernatant were injected in a Merck-Hitachi HPLC system 655A-12 equipped with a 4.6 x 250 mm Nucleosil C18 column (5 pm, RP 18). The system was run at a flow rate of 1 ml min-1 with a methanol/water gradient (10 to 20% methanol in 15 min, then 20 to 100% methanol in 5 min). The UV detector was operated at 281 nm or 275 nm to follow the reduction of quinones 13 and 14, respectively (37). 

L. B. Nilsson, High sensitivity determination of the remoxipride hydroquinone metabolite NCQ-344 in plasma by coupled column reversed-phase liquid chromatography and electrochemical detection , Biomed. Chromatogr. 12 65-68 (1998). 

Hydroquinone can be determined spectropliotometrically at 292 mil in methanol after a sample is evaporated to dryness to remove the interference of acrolein. An alternative method is high performance liquid chromatography on 10-Jim LiClirosorb RP-2 at ambient temperature with 2.0 mL/iniii of... 

Risner, C.H. and S.L. Cash A high performance liquid chromatographic method for the determination of hydroquinone, catechol, phenol, and m- + p-cresol in environmental tobacco smoke R DM, 1989, No. 184, July 13, see www.rjrtdocs.com 508290988 -1013 The determination of hydroquinone, catechol, phenol, and m-H/ -cresols in indoor air samples by high performance liquid chromatography Environ. Tech. 11 (1990) 345-352. 

A variety of methods are available for determining the purity of monomers by the measiu-ement of their saponification equivalent and bromine number, specific gravity, refractive index, and color (68-70). Minor components are determined by iodimetry or colorimetry for hydroquinone or MEHQ, Karl-Fisher method for water content, and tiu-bidimetry for measiuing trace levels of polymer. Gas-liquid chromatography is useful in both the general measurement of monomer purity as well as the identification of minor species within a monomer solution. 

To a mixture of 1-methoxy-l,3-butadiene (1 55.3 g, 0.66 mol) [43] and n-butyl glyoxylate (86.0 g, 0.66mol) [44], 0.1 g hydroquinone was added and the solution was refluxed at 100°C for 6 h under argon. Distillation at 88°-90°C/0.5 tonr gave 2 (R = Bu) (91.6 g, 65%) as a pale-yellow liquid with a faint odor. By gas chromatography this product is a mixture of cis and trans (ca. 7 3) isomers. Treatment of the isomer mixture in dichloro-methane solution with p-toluenesulfonic acid or zinc chloride for 2 h leads to an almost pure trans-isomer (ca. 95%). 

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