Eluents hydrochloric acid

Sorbed ions that are salts of strong acids or bases can be eluted from strongly acidic and basic resins only with large volumes of eluent. Hydrochloric acid is effective for both. A molar solution is generally used, and 30 or more bed-volumes may be needed (one bed-volume is simply the apparent volume of the resin bed). Much smaller volumes of eluent will be needed if the separation can be done with a weakly acidic or basic resin, because elution with IM hydrochloric acid or 2M ammonia rapidly converts the resin to the free acid or base. Since these are virtually nonionic, the sorbed ions fall off, so to speak, and complete elution can be achieved with five bed-volumes or even less. The eluate then contains all the exchangeable ions that were in the column. Similarly, if the sorbed species are anions of weak acids or cations of weak bases, the same eluents will render them virtually nonionic so that they are no longer bound to the resin. 

A solution of 3.5 g 4-(2,3-epoxypropoxy)carbazole in 50 ml absolute alcohol is mixed with 30 ml isopropylamine and heated for 3 hours under reflux. When the reaction is finished, the reaction mixture is evaporated to dryness. The residue obtained is taken up in methylene chloride and chromatographed over an aluminum oxide column (300 g basic aluminum oxide, activity stage IV eluent methylene chloride). The eluted fractions are evaporated and the residue is dissolved in methanol and acidified with 2N ethereal hydrochloric acid. 

In 1952 Carsten (Cl) developed a method, which allowed him to isolate and characterize several lower peptides contained in normal and pathological urine. According to this procedure, urine was desalted on the Amberlite IR-100 column and the adsorbed substances washed out with 2 M ammonia solution. The eluate was then passed through the column of Amberlite IRA-400. This column retained the ampholytes and rejected the weak bases. The former were recovered by elution with 1 M hydrochloric acid and the eluate was subsequently fractionated on Dowex 50 resin with 2M and later 4M hydrochloric acid as the eluents. By applying two-dimensional paper chromatography to further analysis of... 

B. 2,2-(Trimethylenedithio)cyclohexanone. A solution of 3.02 g. (0.02 mole) of freshly distilled 1-pyrrolidinocyclohexene, 8.32 g. (0.02 mole) of trimethylene dithiotosylate4 (Note 2), and 5 ml. of triethylamine (Note 3) in 40 ml. of anhydrous acetonitrile (Note 4), is refluxed for 12 hours in a 100-ml., round-bottom flask under a nitrogen atmosphere. The solvent is removed under reduced pressure on a rotary evaporator, and the residue is treated with 100 ml. of aqueous 0.1 N hydrochloric acid for 30 minutes at 50° (Note 5). The mixture is cooled to ambient temperature and extracted with three 50-ml. portions of ether. The combined ether extracts are washed with aqueous 10% potassium bicarbonate solution (Note 6) until the aqueous layer remains basic to litmus, and then with saturated sodium chloride solution. The ethereal solution is dried over anhydrous sodium sulfate, filtered, and concentrated on a rotary evaporator. The resulting oily residue is diluted with 1 ml. of benzene and then with 3 ml. of cyclohexane. The solution is poured into a chromatographic column (13 x 2.5 cm.), prepared with 50 g. of alumina (Note 7) and a 3 1 mixture of cyclohexane and benzene. With this solvent system, the desired product moves with the solvent front, and the first 250 ml. of eluent contains 95% of the total product. Elution with a further 175 ml. of solvent removes the remainder. The combined fractions are evaporated, and the pale yellow, oily residue crystallizes readily on standing. Recrystallization of this material from pentane gives 1.82 g. of white crystalline 2,2-(trimethylenedithio)cyclo-hexanone, m.p. 52-55° (45% yield) (Note 8). 

It has been found from batch experiments that the base metals Fe, Ni and Co are fully adsorbed by the cation-exchange resin when the hydrochloric acid concentration of the eluent does not exceed 0.4 M. If the concentration exceeds 0.4 M the base metals start to break through. The same thing happens when the hy-... 

Reduction of diaryltellurium dichlorides with samarium diiodide (typical procedure). Diaryl tellurium dichloride (1 mmol) was added to the deep blue solution of Sml2 (2.2 mmol) in THF (22 mL) at room temperature under nitrogen with stirring. The deep blue colour of the solution disappeared immediately and became yellow. The resulting solution was stirred at room temperature under nitrogen for 30 min. To the solution was added dilute hydrochloric acid, and the mixture was extracted with ether. The ethereal solution was washed with brine and dried over MgS04. The solvent was evaporated in vacuo, and the residue was purified by preparative TLC on silica gel (petroleum ether-methylene dichloride as eluent). 

Wang and Li have reported the determination of procaine hydrochloride injections, and the quality control of 4-aminobenzoic acid [144]. The column packing used for this work consisted of 8 g of silanized siliceous earth support with 5 mL of hexanol as the stationary phase, previously percolated with 20 mL of 0.05 M sodium carbonate. The drug injection solution (containing 10 mg of procaine hydrochloride) was applied to the column, and eluted with 30 mL of 0.05 M sodium carbonate. The eluent was diluted to 50 mL with water, and 4-aminobenzoic acid was determined by an absorbance measurement at 266 nm. Procaine was then eluted from the column using 60 mL of 0.1 M hydrochloric acid. This eluent was treated with 10 mL of acetate buffer (pH 6), and diluted to 100 ml with water. The analyte was determined on the basis of its absorbance at 290 nm. Equations for the computation of procaine and 4-aminobenzoic acid concentrations were presented. 

The effects caused by the electrolyte nature of lignin sulfonates are eliminated by using a 0.5M sodium chloride solution as eluent. This eluent is made 0.1M with respect to Tris-HCl and buffered to pH 8 with hydrochloric acid in order to dissolve the proteins used as calibration standards (Fig. 5). 

In order to preclude this problem and the necessary frequent regeneration of the anion system s suppressor column, an ion chromatography exclusion scheme was utilized. Samples collected in a mine environment were reliably concentrated by freeze-drying and then analyzed on an ICE system with dilute hydrochloric acid eluent. The precision of the ICE method was experimentally determined to be 2.5% in a concentration range of 1 to 10 yg/mL. The accuracy was not independently determined but good precision and recovery yield confidence that measured values are within 5% of the true value. No interferences were observed in the ICE system due to strong acids, carbonic acid or other water soluble species present in mine air subject to diesel emissions. 

Samples were collected in midget bubblers containing dilute sodium carbonate solutions. Analysis of formate ion in these solutions was performed using a 500 mm anion separator column and sodium borate eluent. Analysis of formate in these solutions was also performed using the ion chromatography exclusion mode (ICE) using the Dionex IE-C-1 column with dilute hydrochloric acid eluent. 

The reaction mixture is cooled to 0°C, one ol the septa is removed, and excess hydride is quenched by the cautious addition of 10-mL portions of 3 N aqueous hydrochloric acid solution (350 mL total) over 5 min (Note 18). The biphasic mixture is stirred at 23°C for 30 min, then poured into a 1-L separatory funnel. The aqueous layer is separated and extracted with three 150-mL portions of ether. The combined organic fractions are washed with 50 mL of 3 N aqueous hydrochloric acid solution followed by 50 mL of brine. The organic layer is dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure (Note 19). The residue is purified by flash column chromatography (230-400 mesh silica gel, 250 g, 43% ether-petroleum ether as eluent) to afford 4.35 g (90%) of analytically pure (R)-p-methylbenzenepropanol as a colorless oil (Note 20). The ee of this product is determined to be >95% (Note 21). 

Hertog et al. (119) developed a fast HPLC method for the identification and quantification of five major flavonoid aglycones (quercetin, kaempferol, myricetin, luteolin, and apigenin) in freeze-dried vegetable and fruits. However, due to the inadequate resolution of quercetin and luteolin on RP-HPLC on Nova-Pak C]8, two different eluents of different solvent strength and viscosity were utilized. The conditions for hydrolysis and extraction were tested based on different conditions of hydrochloric acid concentration (1.2-2.0 M), reaction period (0.5-6 h), and meth-... 

Actinide retention increases with increasing nitric acid concentration. Tetravalent actinides are more strongly retained than trivalent actinides. Chloro complexes of tetravalent and hexavalent actinides, but not trivalent actinides, are retained from hydrochloric acid solutions (see Figure 9.12). Actinides retained on TRU-Resin columns from nitric acid load solutions can be recovered, individually or in groups, using different acid solutions and/or complexants as eluents. In addition, on-column redox chemistry can be used to shift the valence state of Pu through multistep separation processes so that Pu can be isolated individually. 

Subsequent work by Petersen et al. also used TRU-Resin columns with a HPIC instrument however, the effects of column length were investigated and a 3-cm length was selected.61 Other parameters such as resin size and flow rate were examined, and eluent compositions were studied to minimize the use of oxalic acid. Decreased oxalic acid concentrations reduced the frequency of instrument cleaning. In the final scheme, the Np and Am were eluted in hydrochloric acid, followed by Pu and Th together as tetravalent species in a gradient that added oxalic acid. Last to elute was U. Coelution of Pu and Th was considered satisfactory because isobaric interferences between these elements was not a problem. 

To a solution of previously dried l-[[2-carboxy-3-(2-dimethylaminoethyl)-5-indolyl]methanesulphonyl]-pyrrolidine (1.6 g 0.0442 moles) in anhydrous quinoline (75 ml) and under atmosphere of nitrogen, cuprous oxide (160 mg 0.0011 moles) was added. The reaction mixture was heated to 190°C for 15 minutes, stirred to room temperature, poured into a mixture of 1 N hydrochloric acid (150 ml) and ethyl acetate (50 ml), shaken and decanted. The aqueous solution was washed several times with ethyl acetate, then solid sodium bicarbonate was added until pH = 7.8, and washed with n-hexane to eliminate the quinoline. The aqueous solution was made alkaline with solid potassium carbonate and extracted with ethyl acetate. The organic solution was dried (Na2S04), the solvent removed under reduced pressure when a dark oil was obtained (1.3 g yield 92%). This product was purified by column chromatography with silica gel and methylene chloride ethanol ammonium hydroxide (60 8 1) as eluent and a white foam (0.8 g) of l-[[3-(2-dimethylaminoethyl)-5-indolyl]methanesulphonyl]-pyrrolidine was obtained. To a solution of the above product (0.8 g) in acetone (30 ml), a few drops of hydrogen chloride saturated dioxan solution, were added. The precipitated solid was collected by filtration, washed with acetone and dried to give l-[(3-(2-(dimethylamino)ethyl)-5-indolyl)methanesulphonyl]-pyrrolidine hydrochloride (0.75 g). Melting point 218°-220°C. 

Pumps may also be classified according to the primary construction materials. As illustrated in Figure 3.3, pumps are classified as metallic or nonmetallic, depending on the material used for the eluent flow path. The most commonly used material for HPLC pumping systems is 316 stainless steel because of its mechanical strength, corrosion resistance, good thermal stability, and malleability only a handful of HPLC solvents, such as hydrochloric acid, will cause damage to 316 stainless steel. 

Fig. 9.1 shows the separation of arsenite and arsenate by ion exclusion chromatography using 0.01 mol L 1 hydrochloric acid as the eluent. Arsenious acid is a very weak acid and cannot be detected at low levels by the conductivity detector. However, like sulphide, it is easily detected with the ultraviolet detector. The simultaneous determination of arsenite and arsenate is possible. 

---