Eluent succinic acid

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.

Figure 4.10 Direct analysis of catecholamines in urine sample. Column, Asahipak ES-502C eluent, 75 mM succinic acid + 25 mM borate buffer (pH 6.10) containing 0.5 mM EDTA flow rate, 1.0 min-1 detection, fluorescence reaction detection Ex. 350 nm. Peaks-. 1, adrenaline-, 2, noradrenaline-, and 3, dopamine.

Two resins were tested for the removal of succinic acid from simulated medium on a packed column of sorbent to simulate an actual process on a small scale. It is important to test the sorption with medium, because salts and other nutrients can interfere with the sorption. Table 4 presents the results for XUS 40285 MWA-1 was comparable. This indicates that either sorbent can remove succinic acid efficiently from the fermentation broth without direct loss of product. Both columns were then stripped or regenerated with hot water. Stripping with hot water recovered 70-80% of the succinic acid from the XUS 40285 resin whereas less (50-60%) was recovered from the MWA-1. The XUS 40285 column was stripped with 2 column volumes of hot water with eluent concentrations up to 49 g / L. Succinic acid was concentrated on average to 40 g/L in the XUS resin by this operation and to 30 g/L by the MWA-1. The 10-fold concentration factor bodes well for the use of sorbents to purify the fermentation broth. 

Fig. 3-86. Comparison between the retention behavior of inorganic anions and several organic carboxylic acids, respectively. - Separator column IonPac AS4 eluent 0.0028 mol/L NaHC03 + 0.0022 mol/L Na2C03 flow rate 1.6 mL/min detection suppressed conductivity injection 50 pL solute concentrations a) 1.5 ppm fluoride (1), 2 ppm chloride (2), 5 ppm orthophosphate (3) and bromide (4), 10 ppm nitrate (5), and 12.5 ppm sulfate (6), b) 5 ppm formic acid (7), 40 ppm benzoic acid (8), 20 ppm succinic acid (9), 10 ppm malonic acid (10), 20 ppm maleic acid (11), tartaric acid (12), and oxalic acid (13).

Polystyrene/divinylbenzene-based ion-exclusion columns are also offered by Hamilton Co. (Reno, NV, USA) under the trade name PRP-X300. This is a 10-pm material with an exchange capacity of 0.2 mequiv/g [4], It is obtained by sulfonation of PRP-1, a macroporous PS/DVB polymer with reversed-phase properties. Fig. 4-2 shows the separation of various organic acids on this stationary phase. Dilute sulfuric acid was used as the eluent. The much higher retention of succinic acid compared to acetic acid reveals that the retention of organic acids is chararcterized, apart from reversed-phase effects, by the formation of hydrogen bonds. 

Fig. 4-2. Separation of organic acids on PRP-X300. - Eluent 0.0005 mol/L H2S04 flow rate 1 mL/min detection direct conductivity injection volume 100 pL solute concentrations 4 ppm tartaric acid, 7.5 ppm malic acid and citric acid, 10 ppm lactic acid, 25 ppm acetic acid, and 40 ppm succinic acid.

Table 6.9 lists the relative retention time of the chloride sample anion with the acid eluents chosen for this study. The adjusted retention time of chloride decreases as the retention time for the eluent anion increases and it also decreases as the amount of ionization of the eluent increases. The most satisfactory separations were obtained with either nicotinic acid or succinic acid as the eluent acid. 

Tartaric acid and sulfosalicylic acid eluents, which are acids of low pK, were suitable for rapid separation of strong-acid anions and of cations, but the high background conductivity level gave poor detector response for weak-acid anions. When propionic acid (pK = 4.66) was used as the eluent, resolution of weak-acid anions was improved, but retention times for and Mg were very long. With a succinic acid eluent (pK = 4.00), all analyte ions were well resolved, as shown in... 

A mobile phase containing sulfosalicylic acid or succinic acid seems to work very well. The mobile phase is acidic enough to repress ionization of weakly acidic analytes but the background conductivity is reasonably low. Some of the organic acid in the eluent is adsorbed by the resin, and this leads to improved peak shape. The only downside of this eluent is that a system peak appears later in the chromatogram that may partially coincide with an analyte peak. The system peak stems from partial desorption of the sulfosalicylic or succinic acid when an aqueous sample is injected. 

The cell free samples were mixed with perchloric acid/perchlorate and stored at low temperature for 48 h, at 6000 rpm centrifuged, decanted, stored at -22°C for a week and centrifuged again for deproteination. The separation was performed on an ion exclusion polystyrene/divinylbenzene column at 40 °C with 15 mM sulfuric acid as eluent and detection at 205 nm. For the quantification a standard was applied. A typical chromatogram is shown in Figure 6. Pyruvate, succinate, lactate, formate and acetate were detected in the cultivation medium. 

Although only monovalent anions are included in Table 6.8, similar effects are observed with some divalent anions. Salicylic acid will elute sulfate in 5.2 min and thiosulfate in 7.3 min under the conditions in Table 6.7. However, the weaker eluents such as succinic or nicotinic acid require an excessive amount of time to elute divalent anions. 

Several other organic acids have been used as eluents in anion chromatography. These include succinic, nicotinic, salicylic, fumaric and citric acid [14]. One objective was to find an eluent that is not adsorbed by the resin matrix and that attains equilibrium faster than benzoic acid. The following organic acids, listed in order of their increasing eluting power for sample anions, attain equilibrium fairly rapidly nicotinic, succinic, citric, fumaric, salicylic. 

Up to the present day, a very common method that employs refractive index detection is the simultaneous analysis of main constituents of wine (ethanol, glycerol, glucose, fructose, tartrate, malate, lactate, succinate, acetate, and citrate) [168]. Based on the work of Pecina et al. [169], such separation is usually carried out on HPX-87H (Bio-Rad Laboratories, Hercules, CA, USA) with a dilute sulfuric acid eluent. However, without modifications, the method originally described by Pecina et al. is not suitable for the analysis of wine. In order to separate as many components as possible, column temperature and eluent concentration have to balanced and optimized. Retention times of many organic... 

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