Eluents carbonate

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... 

The checkers determined enantiomeric purity by supercritical fluid chromatography (SFC) using a Chiralpak AD (4.6 x 250 mm) column. Eluent carbon dioxide (300 Bar) modifier methanol (24%) flow rate 1.5 mL/min detection UV (210 nm). Retention times were as follows "diphenylcyclopentanone (3.9 min) (R)-diphenylcyclopentanol (5.9 min) (S)-diphenylcyclopentanol (10.4 min). 

Anions of strong acids may be separated in acidic solution (as in Fig. 6.10) or at a basic pH. Weak acid anions require a basic solution to exist in the anionic form. Separation of borate, silicate, sulfide, cyanide as well as the anions of two stronger acids is shown in Fig. 6.11. An alkaline solution of sodium benzoate was used as the eluent. Carbonate may also be separated under alkaline conditions. Separation of these anions by suppressed IC is usually not attempted because they arc converted to the non-conducting molecular form by the acidic suppressor. 

Figure 10.148 Anion chromatograms of various BPSG-films. Separator column lonPac AS4A eluent carbonate/bicarbonate mixture flow rate 2 mt/min detection suppressed conductivity samples (a) APCVD-film with good flow properties, (b) PECVD-film with bad flow properties, (c) reference standard with...

Figure 10.149 Determination of fluoride, nitrate, sulfate, and orthosilicate in an acid texturization bath used in solar cell manufacturing. Separator column Metrosep A Supp 15 column dimensions 250 mm x 4 mm i.d. column temperature 45 °C eluent carbonate/ bicarbonate mixture flow rate 0.7mL/min detection (a) suppressed conductivity and (b) UV/Vis detection at 410 nm after postcolumn...

Figure 2 Migration of a front using conventional (TLC) and various off-line OPLC developments. HPTLC silica gel 60 (Merck) is compressed for 10 min with 2.5 MPa prior to development, (a) Whole development eluent, carbon tetrachloride flow rate (OPLC), 0.50 cmVmin temperature, 19.5°C 1, conventional development (normal unsaturated chamber) 2, two-directional linear OPLC 3, circularOPLC 4, one-directional linear OPLC. (b) Initial period eluent, chloroform flow rate (OPLC), 0.325 cm /min 1, conventional development (normal unsaturated chamber) 2, theoretical line of linear OPLC 3, linear OPLC, using rapid eluent admission 4, linear OPLC, using Personal OPLC BS 50 5, proposed place of sample application.

Dicarbonyl(cyclopentadienyl)(iodo)iron (152 mg, 0.50 mmol), palladium(II) acetate (5.6 mg, 0.025 mmol), (l.l ,2/ )-iV,iV,iV ,JV -tetramethylcyclohexane-l,2-diamine (6.0 mg, 0.030 mmol), and tetrahydrofuran (1.0 mL) are sequentially added in a 20-mL reaction flask under argon. The mixture is cooled to 0 °C and then phenylmagnesium bromide (1.1-M tetrahy ofiiran solution, 0.68 mL, 0.75 mmol) is added. After the resulting mixture is stirred for 15 min at 0 °C, a saturated ammonium chloride solution (0.2 mL) is added to the reaction mixture. The mixture is filtered through a pad of Florisil, and the filtrate is concentrated. Silica gel column purification (eluent carbon disulfide) of the crude product provided dicarbonyl(cyclopentadienyl)(phenyl)iron 110 mg (87%). ... 

Uranium ores are leached with dilute sulfuric acid or an alkaline carbonate [3812-32-6] solution. Hexavalent uranium forms anionic complexes, such as uranyl sulfate [56959-61-6], U02(S0 3, which are more selectively adsorbed by strong base anion exchangers than are other anions in the leach Hquors. Sulfate complexes are eluted with an acidified NaCl or ammonium nitrate [6484-52-2], NH NO, solution. Carbonate complexes are eluted with a neutral brine solution. Uranium is precipitated from the eluent and shipped to other locations for enrichment. Columnar recovery systems were popular in South Africa and Canada. Continuous resin-in-pulp (RIP) systems gained popularity in the United States since they eliminated a difficult and cosdy ore particle/leach hquor separation step. 

Ion chromatography can be used to determine chloride concentrations of 2—1000 ppb with a carbonate—bicarbonate eluent (23). Eluoride, nitrite, phosphate, bromide, nitrate, and sulfate do not interfere and can be measured simultaneously with a total analysis time of <30 min. 

Figure 12.7 Cliromatograms of a polycarbonate sample (a) microcolumn SEC ti ace (b) capillary GC ti ace of inti oduced fractions. SEC conditions fused-silica (30 cm X 250 mm i.d.) packed with PL-GEL (50 A pore size, 5 mm particle diameter) eluent, THE at aElow rate of 2.0ml/min injection size, 200 NL UV detection at 254 nm x represents the polymer additive fraction ti ansfeired to EC system (ca. 6 p-L). GC conditions DB-1 column (15m X 0.25 mm i.d., 0.25 pm film thickness) deactivated fused-silica uncoated inlet (5 m X 0.32 mm i.d.) temperature program, 100 °C for 8 min, rising to 350 °C at a rate of 12°C/min flame ionization detection. Peak identification is as follows 1, 2,4-rert-butylphenol 2, nonylphenol isomers 3, di(4-tert-butylphenyl) carbonate 4, Tinuvin 329 5, solvent impurity 6, Ii gaphos 168 (oxidized). Reprinted with permission from Ref. (14).

A mixture of 22 parts of 1 -ethyl-1,4-dihydro-5H-tetrazol-5-one,45 parts of 1 -bromo-2-chloro-ethane,26 parts of sodium carbonate,0.3 part of potassium iodide and 240 partsof 4-methyl-2 pentanone is stirred and refluxed overnight with water-separator. The reaction mixture is cooled, water is added and the layers are separated. The aqueous phase is extracted three times with dichloromethane. The combined organic phases are dried, filtered and evaporated. The residue is purified by column-chromatography over silica gel using trichloromethane as eluent. The pure fractions are collected and the eluent is evaporated, yielding 28.4 parts (80%) of 1-(2-chloroethyi)-4-ethyl-1,4-dihydro-5H-tetrazol-5-one as a residue. 

FIGURE 3-23 Schematic of a carbon-fiber amperometric detector for capillary electrophoresis A, fused silica capillary B, eluent drop C, stainless steel plate RE, reference electrode WE, working electrode, AE, auxiliary electrode. (Reproduced with permission from reference 58.)... 

The checkers found that a fraction, b.p. 45-71° (18 mm.), had the following spectral properties infrared (carbon tetrachloride) no absorption in the 3300-1600 cm.-1 region attributable to OH, C=0, or C=C vibrations proton magnetic resonance (chloroform-d) <5, multiplicity, number of protons, assignment 3.1-4.2 (multiplet, 4, CH—Cl, CH—O, and C//2—O), 1.0-2.5 (multiplet, 7, GH3 and 2 x C//2)-Thin layer chromatographic analysis of this fraction on silica gel plates using chloroform as eluent indicated the presence of a major component (the cis- and fraus-isomers), Rf = 0.60, and a minor unidentified component, Rf = 0.14. 

The sulfanes are soluble in carbon disulfide, benzene, tetrachloromethane, and dry diethylether (decreasingly so in that order) while alcohols and aqueous systems initiate rapid decomposition. For this reason a report on the chromatographic separation of the sulfanes H2S by reversed-phase HPLC using methanol as an eluent [35] was shown to be in error The peaks observed in the chromatogram have to be assigned to bismethoxy oligosulfanes... 

Figure 4.13 Solvent strength of eluent nlxtures on alunlna. (o) pentane-carbon tetrachloride, ( ) pentane-n-propyl chloride, (A)...

Figure 18 Very-high-speed gradient anion exchange chromatography of proteins. Column 0.46 x 3.5 cm ZipSep AX, 3 p. Eluent Tris-HCl, pH 8.0, operated on a gradient from 0-0.5 M NaCl. Flow rate 2ml/min. Detection UV absorbance at 280 nm. (1) Ribonuclease A, (2) carbonic anhydrase, (3) conalbumin, (4) bovine serum albumin. (Reproduced from Hatch, R. G., J. Chromatogr. Sci., 31, 469,1993. By permission of Preston Publications, A Division of Preston Industries, Inc.)...

Madden, J. E. and Haddad, P. R., Critical comparison of retention models for the optimization of the separation of anions in ion chromatography II. Suppressed anion chromatography using carbonate eluents, /. Chromatogr. A, 850, 29, 1999. 

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