Eluent hydroxide

The theory of negative peaks for sample anions is easy to understand. Suppose wc use 1.0 X 10 M sodium hydroxide as the eluent. The background conductance will be the sum of the sodium and hydroxide conductances and will be relatively high. Injection of a sample will result in the uptake of the anions by the resin column with an equivalent amount of resin hydroxide ion passing into solution. Once the matrix peak is through, the anion concentration of the column effluent will be constant, as fixed by the 1.0 x 10 M eluent concentration. When a sample anion, A , is eluted from the column and passed through the detector, the eluent hydroxide ion will be decreased because a constant anion concentration must be maintained... 

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. 

Olefins, sultones, alkanes, and alkenesulfonates may be separated by liquid chromatography on silica gel using hexane, trichloromethane-hexane, ethanol-dime thy lcarbonate, and ethanol-ammonium hydroxide as the eluents. Pueschel and Prescher [110] achieved the separation of alkene-1,4-sultone and alkene-1,3-sultone from each other and from other sulfonic acid esters in AOS by thin-layer chromatography on silica gel G with 4 1 diethylcarbonate-ligroine as the... 

Eluent A mixture of toluene, isopropyl alcohol, and ammonium hydroxide (70 29 1), in a nonequilibrated chamber. 

Musumarra et al. [43] identified miconazole and other drugs by principal components analysis of standardized thin-layer chromatographic data in four eluent systems. The eluents, ethylacetate methanol 30% ammonium hydroxide (85 10 15), cyclohexane-toluene-diethylamine (65 25 10), ethylacetate chloroform (50 50), and acetone with the plates dipped in potassium hydroxide solution, provided a two-component model that accounts for 73% of the total variance. The scores plot allowed the restriction of the range of inquiry to a few candidates. This result is of great practical significance in analytical toxicology, especially when account is taken of the cost, the time, the analytical instrumentation and the simplicity of the calculations required by the method. 

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. 

Figure 2. Typical elution curve of arsenate. Eluent 0.1 M sodioum hydroxide, flow rate SV 3 h-1. Elution in run 1-3 in Table 2.

Figure 4.18 Analysis of anions in water using ion-pair liquid chromatography. Column, octadecyl-bonded silica gel, 15 cm x 4.6 mm i.d. eluent, 2 mM tetrabutyl-ammonium hydroxide (pH 5.3) in 3% acetonitrile-water flow rate, 1 ml min- detection, UV200 nm. Peaks 1, Br 2, N03 and3,1. ...

Other eluent systems in suppressed ion chromatography are typically chosen based on specific separation requirements. For routine analysis of monovalent and divalent anions, carbonate-based eluents represent a reasonable alternative to hydroxide-based eluent systems. Carbonate eluents are simple to prepare and can be useful in cases where anion analysis is only occasionally performed. It must be kept in mind, however, that carbonate lowers the detection sensitivity for anionic species and introduces significant nonlinearity into the analysis. ... 

FIGURE 13 Potassium hydroxide eluent generator schematic. 

The use of formic acid, acetic acid and ammonium formate rather than triflu-oroacetic acid can substantially increase sensitivity because their proton affinities are lower than that of the TFA anion - though TFA is often used in the analysis of peptides. It is always advisable to keep the level of acid additives to less than 0.1% v/v, and preferably 0.03-0.05% v/v, in the final eluent. Triethylamine or ammonium hydroxide can be used successfully in negative mode because they promote deprotonation of acidic species. 

Elemental composition Cr 52.00%, 0 48.00%. The compound may he identified from its dark red color. Other color phases are noted above. Chromium may he measured in the aqueous phase hy AA, ICP or x-ray techniques, or in the solid phase hy x-ray methods. Hexavalent chromium (Cr6+) may he analyzed hy ion chromatography. For this, the aqueous sample is adjusted to pH 9 to 9.5 with a concentrated buffer (ammonium sulfate and ammonium hydroxide mixture) and mixed into the eluent stream of the buffer. Cr " is separated from Cr + on a column, and derivatized with an azide dye as a colored product measured at 530 nm, which is identified from its retention time. (APHA, AWWA, and WEF. 1999. Standard Methods for The Examination of Water and Wastewater, 20th ed., Washington, DC American Public Health Association.)... 

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