Eluents sodium phenolate

A solution of sodium phenolate, and, later, a mixture of sodium carbonate and bicarbonate, were used as the eluent for the separation of anions on an anion-exchange column. A cation-exchange stripper column was used to reduce the background conductance of the eluent and to enhance the conductance of sample anions such as chloride. 

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. 

Figure 25-12 Isocratic HPLC separation of a mixture of aromatic compounds at 1.0 mL/min on a 0.46 x 25 cm Hypersil ODS column (C,8 on 5-jxm silica) at ambient temperature ( 22 C) (1) benzyl alcohol (2) phenol (3) 3, 4 -dimethoxyacetophenone (4) benzoin (5) ethyl benzoate (6) toluene (7) 2,6-dimethoxytoluene (8) o-methoxybiphenyl. Eluent consisted ot aqueous buffer (designated A) and acetonitrile (designated B). The notation 90% B in the first chromatogram means 10 vol% A and 90 vol% B. The buffer contained 25 mM KH2P04 plus 0.1 g/L sodium azide adjusted to pH 3.5 with HCI.

HFB derivatives were also applied to the determination of phenols in water [12] at the 10 ng/ml level. A 25 ml sample of water was acidified with concentrated hydrochloric acid to pH 1 and 25 ml of benzene were added. The mixture was agitated for 15 min and allowed to stand until the layers separated. Portions of 2 ml of the benzene extract were dried by passage through a 5 cm X 5 mm glass column packed with anhydrous sodium sulphate. A 1-ml volume of the eluent was taken into a 4-ml glass vial and 5 pi of HFB— imidazole reagent were added. The vial was closed and the reaction solution was heated... 

A typical procedure for Eq. (78) [153] is as follows. In a 100-ml two-necked flask with a reflux condenser, a balloon, and a rubber cap are placed Pd(OAc)2 (0.05 mmol), Cu(OAc)2 H2O (0.05 mmol), and molecular sieves 4 A (400 mg). After the apparatus is evacuated by pumping, nitrogen (750 ml) is introduced. Then the phenol (1 mmol), the alkene (3 mmol), DMF (5 ml), and air (150 ml) are injected into the flask, and the resulting mixture is stirred at 100 °C for 9 h. After cooling, the mixture is extracted with diethyl ether and dried over sodium sulfate. The coupling product is isolated by column chromatography on silica gel using hexane-ethyl acetate (99.5 0.5, v/v) as eluent. 

Fig. 3-76. Analysis of iodide and thiocyanate in the presence of high amounts of sodium chloride. — Separator column IonPac AS5 eluent 0.0017 mol/L NaHC03 + 0.0018 mol/L Na2C03 + 100 mg/L p-cyano-phenol flow rate 2 mL/min detection suppressed conductivity injection volume 50 pL solute concentrations 10 ppm iodide and thiocyanate in 1% NaCl.

To a stirred suspension of 176 mg sodium hydride (60% in oil, 4.4 mmol) in 20 mL THE at room temperature under argon atmosphere was added 0.376 g phenol (4.0 mmol) in portions followed by a catalytic amount of hydroquinone. The mixture was stirred for 0.5 h. HMPA (2 mL) and 0.74 mL geranyl chloride (4.0 mmol) were successively added. The whole mixture was stirred for 1 day. After decomposition of excess sodium hydride with 0.5 niL methanol, the mixture was poured onto ice water and extracted with ether. The combined organic layers were dried, concentrated, and purified by column chromatography on silica gel (hexane-dichloromethane as eluent). 

Evans et reported the HPLC-ED of plasma salicylate (2-hydroxybenzoate). A LoD of 4 ng on column was claimed. The eluent used was methanol-aq. sodium acetate (approximately 60mmolL pH 6.0) (4 - - 46). However, the column used was not stated, a protracted sample purification procedure was needed, no internal standard was used and the applied potential advocated (GCE, -I-1.35 V vs Ag/AgCl) was very high by comparison with other methods involving the ED of phenolic hydroxyl groups. 

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