Separations of carboxylic acids

Fig. 1 Schematic representation of the chromatographic separation of carboxylic acids. Maleic acid (1), pimelic acid (2), succinic acid (3), benzoic acid (4), malic acid (5), tartaric acid (6), lactic acid (7), stearic acid (8), arachidic acid (9), suberic acid (10), mixture (M).

FIGURE 15.3 PLC separation of carboxylic acids from soluble organic matter with the use of carboxylic acids esterification based on experimental data given in Reference 36, Reference 67 to Reference 69, and Reference 102 to Reference 104. 

Chiu, G., Separation of carboxylic acids by temperature programmed liquid chromatography, /. HRC CC, 9, 410, 1986. 

Hajos, P., and Nagy, L., Retention behaviors and separation of carboxylic acids by ion-exchange chromatography, /. Chromatogr. B, 717, 27, 1998. 

Kwakman et al. [65] described the synthesis of a new dansyl derivative for carboxylic acids. The label, N- (bromoacetyl)-A -[5-(dimethylamino)naphthalene-l-sulfonyl]-piperazine, reacted with both aliphatic and aromatic carboxylic acids in less than 30 min. Excess reagent was converted to a relatively polar compound and subsequently separated from the derivatives on a silica cartridge. A separation of carboxylic acid enantiomers was performed after labeling with either of three chiral labels and the applicability of the method was demonstrated by determinations of racemic ibuprofen in rat plasma and human urine [66], Other examples of labels used to derivatize carboxylic acids are 3-aminoperylene [67], various coumarin compounds [68], 9-anthracenemethanol [69], 6,7-dimethoxy-l-methyl-2(lH)-quinoxalinone-3-propionylcarboxylic acid hydrazide (quinoxalinone) [70], and a quinolizinocoumarin derivative termed Lumarin 4 [71],... 

Figure 4.7 Anion exchange separation of carboxylic acids in red wine. Column, Shodex C811, 100 cm x 7.6 mm i.d. eluent, 3 mM perchloric acid flow rate, 0.9 ml min-1 temperature, 60 °C detection, reaction detection using chloro-phenol red at 430 nm. Peaks 1, citric acid 2, tartaric acid 3, malic acid 4, succinic acid 5, lactic acid 6, formic acid and 1, acetic acid.

Fig.4.38. Separation of carboxylic acids by ion-pair chromatography. Stationary phase N,N-dimethyl-protriptyline, 0.036 M, pH 9.0 (30% on cellulose). Mobile phase cyclohexane-chloroform-1-pentanol (15 4 1). Mobile phase speed 2 mm/sec. Column 300 X 2.7 mm I.D. Peaks B benzilic acid (0.7 nmole) P = phenylbutyric acid (1.1 nmoles) S = salicylic acid (1.4 nmoles).

Figure 6.11 Separation of carboxylic acids (10 mJW each) by suppressed conductivity capillary electrophoresis. Conditions capillary, 60 cm X 75 jum I.D. fused silica voltage, +24 kV detection, suppressed conductivity using 15 mJV sulfuric acid as regenerant. Peaks (ppm) 1, quinic (1.92) 2, benzoic (1.44) 3, lactic (0.90) 4, acetic (0.60) 5, phthalic (1.66) 6, formic (0.46) 7, succinic (1.18) 8, malic (1.34) 9, tartaric (1.50) 10, fumaric (1.16) 11, maleic (1.16) 12, malonic (1.04) 13, citric (1.92) 14, isocitric (1.92) 15, cis-aconitic (1.74) 16, oxalic (0.90). (Reprinted from Ref. 63 with permission.)...

Fig. 9.1. Separation of carboxylic acids and hydrophobic compounds with (a) LC and (b) pressure supported CEC ((1) folic acid, (2) p-hydroxybenzoic acid, (3) acetylsalicylic acid, (4) nicotinic acid, (5) thiourea and (6) nicotinamide). Capillary 15 cm x 100 pm I.D. packed with Nucleosil 100 3-Cis (3 pm). Conditions disodium tetraborate (20 mM, pH 8.5)-methanol, 25 75 (v/v) 63 bar at the inlet vial (a,b) -6 kV (b). Reproduced from [17], with permission.

Kabra MM, Netke SA, Sawant SB, Joshi JB, and Pangarkar VG. Pervaporative separation of carboxylic acid-water mixtures. Sep. Tech. 1995 5(4) 259-264. 

Recovery from fermentation broth and separation of carboxylic acids, amino acids were tested by many authors using layered BLM, rotating, creeping, spiral-type FLM, HELM, HLM, and MHS-PV techniques of the OHLM processes. The research works for the last 15 years in this field classified according to the OHLM techniques with types of membrane walls and carriers used are provided in Table 13.7. 

Figure 12.6 Separation of carboxylic acids by ion exclusion on a cation exchanger [reproduced with permission from E. Rajakyla, J. Chromatogr., 218,695 (1981)]. Conditions column, 30cm x 7.8 mm i.d. stationary phase, Aminex HPX-87, 9ixm mobile phase, 0.8 ml min of 0.006 N H2SO4 temperature, 65°C UV detector, 210 nm. Peaks 1 = oxalic acid 2 = maleic acid 3 = citric acid 4- — tartaric acid 5 — gluconic acid 6 — malic acid 1 = succinic acid 8 — lactic acid 9 — glutaric acid 10 = acetic acid 11= levulinic acid 12 = propionic acid.

Eyal, A.E. and Bressler, E. (1993). Mini-review industrial separation of carboxylic acid and amino acids by hquid membranes Appheabflity, process considerations and potential advantages. Biotechnol. Bioeng., 41, 287-95. 

It has long been held that a separation of carboxylic acids by lEC requires the use of an acidic eluent to repress ionization of the analytes and thereby give sharp pcak.s. However, equilibrium constant calculations indicate that alkane carboxylic acids are... 

Adsorption of a layer of alcohol on the polymeric resin surface is believed to explain the dramatic effects observed in our separations of carboxylic acids. Butanol has the highest distribution coefficient of the alcohol moderators studied, and only a low concentration in the aqueous eluent is needed to coat the resin. surface. Partitioning of the various solute acids between the predominately aqueous eluent and the coated resin surface is much different that it is with an uncoated polystyrene surface. 

J. Morris and J. S. Fritz, Eluent modifiers for the liquid chromatographic separation of carboxylic acids using conductivity detection. Anal. Chem., 66,2390,1994. 

Volgger, D., Zemann, A. J., Bonn, G. K., and Antal, M. J., High-speed separation of carboxylic acids by co-electroosmotic capillary electrophoresis with direct and indirect UV detection, J. Chromatogr. A, 758, 263-276, 1997. 

Fig. 5.6-11 Lipase facilitated separation of carboxylic acids using a supported ionic liquid membrane [118].

Kanitsar, K., et al.. Influence of organic modifiers on the separation of carboxylic acids using co-EOF capillary electrophoresis, J. Liquid Chromatogr., 26, 455, 2003. 

FigureS.1 Gradient separation of carboxylic acids with background correction with a 15 cm X 4.1 mm Hamilton PRP-X300 column of 0.17 mequiv g" exchange capacity. Gradient ...

Figure S.3 Separation of carboxylic acids and hydroxycarboxylic acids on lonPac ICE-AS6. Eluent 0.4 mmol/L heptafluorobutyric acid flow rate 0.4 mL/min detection suppressed conductivity injection volume 50 pU peaks 5mg/L oxalic acid (1), lOmg/L tartaric add (2), 15mg/L citric acid (3), 20mg/L malic add (4),...

---