Amberlite eluent

A number of minor components present in commercial neomycin have been separated by column chromatography on a carboxylic cation-exchange resin, Amberlite CG-50 99. The components were eluted from the resin with ammonium hydroxide solution. T.L.C. of the eluent fractions showed the presence of two previously unreported impurities which were then isolated on Dowex 1X2 and tentatively identified using NMR and mass spectrometry. 

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... 

According to Patel et al. (140), Amberlite XAD-2 can also be used to separate water-soluble food colors. Food colors were retained only with neutral eluent (methanol). By changing the concentration of methanolic sulfuric acid, selective elution of colors is achieved. 

Another system consisting of Amberlite IRA-400, using 80% acetic acid as an eluent, has been also described (107). 

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. 

Davenport and Johnson [30] used ion exchange chromatography on Amberlite IRA-900 strongly basic resin to determine nitrate and nitrite in water. 0.10M perchloric acid was used as eluent and an electrochemical cadmium electrode detector was used. 

Fig. 6.22 Measured and calculated isotherms for pure components and mixtures of glucose and fructose (adsorbent ion exchange resin Amberlite CR 1320 Ca, dp = 325 im, eluent water for additional data see Appendix B.3).

Trace amounts of molybdenum have been separated from natural waters by retention of the anionic Mo-thiocyanate complex on the anion-exchanger Dowex 1. Mixtures of 2 A/ HCIO4 and 1 M HCl are used for the elution [24]. The Mo-thiocyanate complex has also been concentrated on the anion exchanger Amberlite XAD [25,26], with the use of acetone as the eluent [25]. Molybdenum has been retained on anion-exchange columns from an HCl medium prior to being determined by the thiocyanate method [27-30]. Mo has been sorbed selectively (pH 3.5) on the anion exchanger Sephadex G-25, from which it can be eluted withEDTA [31]. 

Amberlite resin CG-120 (H) Type 1 100-200 mesh [Fluka Chemical] may also be used with 0.60 M HCl as eluent. 

Transfer (18) (384 mg, 0.61 mmol) to a dry 5 ml two necked flask equipped with a reflux condenser and establish an inert atmosphere, that should be maintained throughout the reaction. Add BuaSnH (0.5 ml, 1.83 mmol) and AIBN (30 mg). Heat the mixture under reflux for no more than 30 min. Remove the solvent in vacuo and purify the residue by flash chromatography using silica gel and ethyl acetate/hexanes 5 8, as the eluent to afford (19) in 57% yield. Transfer (19) to a dry 50 ml round bottomed flask and establish an inert atmosphere that should be maintained throughout the reaction. Dissolve (19) in MeOH (15 ml). Add a 0.5 M solution of MeONa in MeOH (1 ml) and leave the solution to stir at room temperature for 30 min. Then neutralize the reaction mixture with methanol-washed Amberlite IR-120 (H ) resin. Remove the resin by filtration to afford the organic filtrate which is concentrated in vacuo. Re-dissolve the residue in water (10 ml) and add Amberlite IR-120 (H ) ion-exchange resin, previously washed with hot (70 °C) water, to the solution and heat the mixture at 70 °C for 2.5 h. Remove the resin from the cooled solution by filtration, and concentrate the filtrate to give pure (20) in 89% yield. 

Matrix solid-phase extraction (MSPE) is a recently introduced alternative to SPE in which samples are thoroughly mixed with a solid substrate, then packed into a column and washed and eluted with solvents, so the sample cleanup and analytes extraction are carried out in a single step. The solid support can be CIS- or C8-bonded silica ° 2 or Amberlite XAD-2, and even the use of sea sand as solid substrate has also been reported recently. As in the traditional chromatographic and SPE procedures, extraction conditions, especially the composition of the eluents, need to be optimized before the extraction. 

The simplest version of such CFS was that developed for the rapid SPE-derivatization, with volume-based sampling (1 ml of urine), of various abuse drugs (barbiturates, opiates, and cocaine, among others) in real human urine [19]. The sorbent material was polymeric Amberlite XAD-2 and there were no restrictions on the retention pH as all the drugs assayed exhibited maximum adsorption within the range 6 to 9, which is within the normal urine pH range. The derivatis-ing reagent for silylation, BSTFA, was added to the eluent (trichloromethane... 

The separation is performed on a column of Amberlite CG-50, 25 x 400 mm, mixed Na" and H form, thermostatted at 35-C. An eluent of 30 70 2-PrOH/0.5 M NaCl solution is used, with the column effluent checked batchwise by the methylene blue method to detect... 

---