Chromatography of Aromatic Acids

Lange, H.W. and Hempel, K., Automated chromatography of aromatic acids, aldehydes, and alcohols with an amino acid analyzer, /. Chromatogr., 59, 53,1971. 

Gas Chromatography of Aromatic Acids as Their Trimethylsilyl Derivatives, Including Applications to Urine Analysis... 

Coward, R.F. and Smith, P. (1969a), The gas chromatography of aromatic acids as their trimethylsilyl derivatives, including applications to urine analysis. J. Chromatogr., 45, 230. 

Horii, Z., Makita, M., Takeda, I., Tamura, Y. and Onishi, Y. (1965a), Gas chromatography of aromatic acids. Chem. Pharm. Bull., 13,636. 

The agreement between the observed and predicted k values of aromatic acids was within 10%. The correlation coefficient was 0.954 (n = 32). An error of greater than 10% for 3-hydroxy-2-naphthoic acid and 2-hydroxybenzoic acid was attributed mainly to an error in their K.A values.25 The partition coefficient, logP, and dissociation constant, pKA, of analytes can be obtained by simple calculations and by computational chemical calculations, and thus the retention time can be predicted in reversed-phase liquid chromatography. 

Fio. 36. Vloi t Hoff plou of the retention bctors of aromatic acids in reversed-phase chromatography using octadecyl silica as the stationaiy phase and neat aqueous 30 taM NaHiPO buffer (pH 2.0) (open symbols), or the same buffer containing 696 (v/v) of aceloni ti (closed symbols) as the eluent. Column S imSpherisorbODS, 230 x 4.6 mm. Eluites 3.4xlihydroxymandelic acid (O. ) 4 hydroxymandelic acid ( , ) 4-hydroxyphenylacetic acid (7. ) 3,4-dihydroxyphenylacetic acid (A, A). Reprinted with permission from Me-lander tt at. U77). 

Li, L., Liu, M., Da, S., and Feng, Y. (2004) High Performance Liquid Chromatography of Aromatic Carbonxylic Acids on p-tert-butyl-calix[8]arene-bonded Silica Gel Stationary Phase, Talanta 62, 643-648. 

Quinoxalinones have been suggested for the chromatography of keto acids [184,185]. They are produced by reaction with aromatic o-diamines, as shown in Scheme 4.21 (p. 77). A solution of 60 mmol of sublimed o-phenylenediamine in 100 ml of 10% acetic acid was mixed with a solution of 30 mmol of the keto acid in 30 ml of water. The precipitated quinoxalinone was filtered after 15 min, washed with water, dried and crystallized from methanol. Prior to the GC analysis proper, it had to be converted into a silyl derivative 5—50 /ul of about a 1% solution of quinoxalinone in dry pyridine was mixed with 20 jul of a pyridine solution of the internal standard (6-methyl-2-naphthol, p-nitrophenyl phenyl ether). A 200-/lz1 volume of BSA and 50 of pyridine were added. As the silylation proceeded very quickly, the reaction mixture could be injected immediately. 

Fan, X. and Deng, Y., Separation and identification of aromatic acids in soil and the Everglades sediment samples using solid-phase microextraction followed by capillary zone electrophoresis. Journal of Chromatography, A, 979, 417, 2002. 

Paper chromatography of amino acids is best described as partition chromatography between the stationary aqueous (most polar) phase in the cellulose fibers and the mobile (least polar) phase formed by the solvent system used. The actual situation is somewhat more complicated. The stationary phase cannot be described as pure water but rather as a concentrated aqueous carbohydrate solution. Elements of adsorption chromatography are involved as shown by the relatively small/ f values for aromatic amino acids and by the possibility of separating enantiomers (mirror images) of amino acids depending on the chirality of the cellulose in the paper. 

T. Hanai, Chromatography in silica, quantitative analysis of retention of aromatic acid derivatives,/. Chromatogr. Set, 2006, 44, 247-252. 

T. Hanai and J. Hubert, Optimization of retention time of aromatic acids in liquid chromatography from log P and predicted pKa values,/. High Resolut. Chromatogr. Chromatogr. Commun., 1984, 7, 524-528. 

Hanai, T. Kaneko, K. Homma, H. Semi-micro bquid chromatography of aromatic amino acid metabobtes using isocratic elution and column switching. Biomed. Chromatogr. 2002,16.420-424. 

Jones, P. Wellington, C.A. Optimisation in chromatography Theory and application to the separation of aromatic acids in reversed-phase liquid chromatography. J. Chromatogr. 1981, 213, 357-361. 

For gas chromatography of aromatic hydroxy acids on silicone rubber plus polyethylene glycol as stationary phase see (114). 

Hill, A., Hoag, G.N. and Zaleski, W.A. (1972), The investigation of aromatic acids in phenylketonuria, alkaptonuria, and tyrosinosis using gas-liquid chromatography. Clin. Chim. Acta, 37,455. 

Bentone-34 has commonly been used in packed columns (138—139). The retention indices of many benzene homologues on squalane have been determined (140). Gas chromatography of C —aromatic compounds using a Ucon B550X-coated capillary column is discussed in Reference 141. A variety of other separation media have also been used, including phthaUc acids (142), Hquid crystals (143), and Werner complexes (144). Gel permeation chromatography of alkylbenzenes and the separation of the Cg aromatics treated with zeofltes ate described in References 145—148. 

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