Eluents sodium hydroxide

In principle, salts derived from inorganic or organic acids, with pK values above 7 can be employed as the eluent. Sodium hydroxide has proved to be particularly suitable, because it is converted into water independent of the initial concentration. The resulting background conductivity is hardly affected by the hydroxide ion concentration in the... 

The recovered resin can be reconverted to the hydroxide form by eluting a column of the material with aqueous 10% sodium hydroxide until it is free of halide ion (silver nitrate-nitric acid test) and then with water until the eluent is no longer alkaline to pH paper. 

Eluent degassing is important due to trap in the check valve causing the prime loose of pump. Eoss of prime results in erratic eluent flow or no flow at all. Sometimes only one pump head will lose its prime and the pressure will fluctuate in rhythm with the pump stroke. Another reason for removing dissolved air from the eluent is because air can get result in changes in the effective concentration of the eluent. Carbon dioxide from air dissolved in water forms of carbonic add. Carbonic add can change the effective concentration of a basic eluent including solutions of sodium hydroxide, bicarbonate and carbonate. Usually degassed water is used to prepare eluents and efforts should be made... 

Elution of Non-Sulfonated Lignins with Sodium Hydroxide Solution as Eluent... 

Non-sulfonated lignins such as those from alkaline pulping processes are insoluble in water but easily soluble in sodium hydroxide solutions. When dissolved in and eluted with a sodium hydroxide solution, they show polyelectrolyte properties, i.e., the molecular species interact. As revealed by Figure 9, the fractionation result is strongly dependent on the sodium hydroxide concentration up to a concentration of 0.4M. A 0.5M sodium hydroxide solution is thus an appropriate eluent for fractionation on Sephadex G-50 (3). 

With 0.5M sodium hydroxide as eluent, Sephadex G-50 effects fractionation in the molar mass range 1000-15000 dalton and can be used for a period of 3-4 weeks with a single calibration carried out with proteins and polypeptides of known molar mass, as revealed by Figure 10. Relative retention volumes 0.0 and 1.0 are defined with Blue Dextran and phenol, respectively. 

Fractionation on Sephadex G-25 using 0.5M sodium hydroxide as eluent causes the low molar mass lignin components in black liquor to elute in the relative retention volume range 0.3-1.3 with partial separation from each other, as shown in Figure 11. 

Figure 9. Influence of sodium hydroxide concentrations in the eluent on fractionation of lignins in draft black liquor. Column Sephadex G-50. (Reprinted with permission from ref. 3. Copyright 1976 Wiley.)...

In Fig. 2, the columns were IonPac ICE-AS6 (250X9-mm i.d.), AG9-HC (concentrator, 50X4-mm i.d.) and AG9-HC/AS9-HC (analytical, 250X2-mm i.d.). The ion exclusion sample treatment eluent was deionized water and the flow rate was 0.55 ml/min. The sample volume was 750 pi. The ion exchange eluent was 8.0 mM sodium carbonate and 1.5 mAf sodium hydroxide. The flow rate on the 2-mm analytical column was 0.25 ml/ min. Detection was by suppressed conductivity using the ASRS -I electrolytically regenerated suppressor in the external water mode. 

Figure 2. Ion chromatographic separation of a series of anions on polymer-based column with adsorbed decyl-2.2.2 using gradient capacity from sodium hydroxide to lithium hydroxide aqueous eluent. Anions 1) fluoride 2) acetate 3) chloride 4) nitrite 5) bromide 6) nitrate 7) sulfate 8) oxalate 9) chromate 10) iodide 11) phosphate 12) phthalate 13) citrate 14) thiocyanate (from refs. 13,14)...

A mixture of 4-[4-(diphenylmethyl)-l-piperazinylmethyl]-Nl-ethyl-l,2-benzenediamine and acetic acid is stirred at room temperature till all solid enters solution. Then there are added pentyl ethanimidate hydrochloride and stirring is continued first for 1 h at room temperature and further for 1 h at reflux. The reaction mixture is evaporated and the residue is stirred in water. The whole is alkalized with a sodium hydroxide solution and the product is extracted with dichloromethane. The extract is dried, filtered and evaporated. The residue is purified by column-chromatography over silica gel using a mixture of trichloromethane and methanol as eluent. The pure fractions are collected and the eluent is evaporated. The product is filtered off and dried, yielding 5-[4-(diphenylmethyl)-l-piperazinylmethyl]-l-ethyl-2-butyl-lH-benzimidazole melting point 124.8°C (crystallized from 4-methyl-2-pentanone). 

To an ice-cooled solution of N-methyl-l-naphthalenemethylamine hydrochloride (2.1 g) in methanol (40 ml) and water (10 ml) was added sodium hydroxide powder (2 g) followed by dropwise addition of epichlorohydrin (8 ml). The mixture was heated at 60°C for 3 h, then cooled to room temperature. Volatile materials were removed in vacuo and the residue was taken up in ethyl acetate and washed with water. The organic phase was collected, dried over sodium sulfate, filtered and evaporated to dryness. The crude mixture was purified by flash chromatrography on silica gel (grade 9385, Merck, 230-400 mesh, 60 A) using a solvent gradient of a mixture of hexane and ethyl acetate (95 5, 90 10 and 85 15) as eluent, affording the N-methyl-N-naphthylmethyl-2,3-epoxypropane (1.85 g, 81.5%) as an oil. 

Oikawa and Saitoh [89] reported studies of the application of ion chromatography to the determination of fluoride, chloride, bromide, nitrite, nitrate, sulphate, sulphite and phosphate ions in 3 ml samples of rainwater. The results show that the most suitable eluent for this purpose is 2m mol L 1 sodium carbonate/5m mol L 1 sodium hydroxide. The reproducibility of the determination was satisfactory for standard solutions of all the ions except nitrite. This problem was solved by preparing standard and sample solutions with the same composition as the eluent. 

EDTA eluent (lm mol L-1) was prepared by dissolving ethylene diaminetetraacetic acid disodium salt in deionised water and adjusting to pH 6.0 with O.lmol L 1 sodium hydroxide. 

Borate is selectively concentrated on Amberlite XE-243 ion exchange resin and converted to tetrafluoroborate using 10% hydrofluoric acid. Tetrafluoroborate is strongly retained by the resin, thus allowing excess fluoride to be eluted without loss of boron. The tetrafluoroborate is eluted with lmol L 1 sodium hydroxide and is determined in the eluent by ion chromatography. Boron is quantified to a lower limit of 0.05mg L 1. 

Fig. 8.23. CEC—ESI-MS analysis of steroids. Column, 450 x 0.1 mm i.d. packed with 3 pm Sherisorb ODS-1 eluent, 4 mmol/1 sodium tetraborate-sodium hydroxide, pH 8.0, 70% acetonitrile applied voltage, 21.5 kV detection, ESI-MS, 370-470 amu sheath liquid, 0.1% formic acid, 50% methanol, 6 pl/min injection, electrokinetic, 5 kV, 10 s sample, bufalin, cinobufagein, digitoxigenin, cinobufatalin, digoxigenin, gitoxigenin (in order of elution). (Reproduced from ref. [81 ] with permission of John Wiley Sons.).

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