Eluents nitric acid

Figure 10.383 Analysis of diethylenetriamine-penta(methylenephosphonic add) in formation water with on-column preconcetration on a high-capacity anion exchanger. Separator column lonPac AS11-HC with NG1 guard column eluent nitric acid gradient linear.

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. 

Castro and Canselier [114] similarly used reverse phase HPLC with methanol-water containing a low concentration of nitric acid as eluent. Quantification was made possible by using a moving-wire flame ionization detector. 

Pantsar-Kallio and Manninen [85] optimised a unique coupled cation- and anion-exchange chromatographic system for Cr speciation. The need for Cr(III) species conversion by oxidation was eliminated by the use of dilute nitric acid eluents. Detection limits using the system were 0.3 pig l-1 for Cr(III) and 0.8 pug 1—1 for Cr(VI) in lake water samples. 

Goossens and Dams [89] developed a method to separate chlorine and sulphur interferents from V, Cr, Cu, Zn, As and Se in various samples using a Dionex-1 anion-exchange column and dilute nitric acid eluent. The analytes were collected in the eluent whereas Cl-, CIO, S04- and SO3- interferents... 

Actinide retention increases with increasing nitric acid concentration. Tetravalent actinides are more strongly retained than trivalent actinides. Chloro complexes of tetravalent and hexavalent actinides, but not trivalent actinides, are retained from hydrochloric acid solutions (see Figure 9.12). Actinides retained on TRU-Resin columns from nitric acid load solutions can be recovered, individually or in groups, using different acid solutions and/or complexants as eluents. In addition, on-column redox chemistry can be used to shift the valence state of Pu through multistep separation processes so that Pu can be isolated individually. 

Kidney, liver, femur Microwave digestion with nitric acid addition of internal standard and dilution with eluent SEC/ICP-MS 0.04 g/g 100 14% of spiked Al in reference material Owen et al. 1994... 

Due to its ability to withstand high pressure, its relative low cost, and inertness, stainless steel has become the standard material of columns and other chromatographic components. However, under certain circumstances, stainless steel has been shown to interact with the sample and the mobile phase [39]. The best known example is chloride salt corrosion of stainless steel. Data indicate that nearly all common eluents dissolve iron from stainless steel [39]. It appears that proteins also adsorb to stainless steel [39], The adsorption process is fast, whereas desorption is slow, a result which leads to variable protein recoveries. A number of manufacturers are offering alternatives to stainless components with Teflon -lined columns and Teflon frits. Titanium is being explored as an alternative to stainless steel. A cheaper and simpler procedure is to oxidize the surface of the stainless steel with 6N nitric acid. This procedure should be repeated about every 6 months. 

Eluent. Methanol ammonium nitrate buffer solution (90 10). To prepare the buffer solution add 94ml of strong ammonia solution and 21.5ml of nitric acid to 884 ml of water and adjust to pH 10 by the addition of strong ammonia solution. 

In this work, batch and column experiments were carried out to investigate the ion exchange characteristics including the effects of the ionic group of ion exchangers, the concentration of nitric acid, the feed rate and also the elution characteristics of Pd(II) by various eluents for obtaining the optimal separation conditions. 

The elution characteristics of Pd(I0 in the batch and packed column showed that Pd could be easily eluted by O.S M thiourea and 0.1 M nitric acid mixed solution. The capacity for the elution of Pd(Il) by O.S M thiourea and 0.1 M nitric acid mixed solution was high compared with the other eluents such as nitric and hydrochloric acid solutions. 

While the type of available eluent depends upon the detection method being applied in anion exchange chromatography, a corresponding classification is not necessary in cation exchange chromatography. For the separation of alkali metals, ammonium, and small aliphatic amines, mineral acids such as hydrochloric or nitric acid are typically used as eluents, independent of whether the subsequent conductivity detection is performed with or without chemical suppression. The concentration range lies between 0.002 mol/L and 0.04 mol/L. Bachmann et al. [141] employed cerium(III) nitrate in very low concentrations as the eluent for the indirect fluorescence detection of alkali metals. 

The eluents suitable for the separation of amino acids on latex cation exchangers do not comprise the classical citrate/borate buffers but mixtures of nitric acid and potassium oxalate. In comparison to buffers composed of sodium citrate and borate, these components may be obtained at much higher purity. The retention of the amino acids to be analyzed, however, is possibly affected by the sample pH due to the limited buffer capacity of the eluents that are based on nitric acid and potassium oxalate. Fig. 4-21 shows the separation of a calibration standard for collagen hydrolysates on an Amino Pac PA-1 latex cation exchanger at ambient temperature. The advantage is the short... 

Alternatively, a strongly conducting eluent may be used. In this case, elution of the solute ions is associated with a negative conductivity change. This indirect detection method is applied to the separation of anions with potassium hydroxide as the eluent [7], A corresponding chromatogram is displayed in Fig. 6-2. This indirect detection method is also utilized in the analysis of mono- and divalent cations, which are eluted by dilute nitric acid or nitric acid/ethylenediamine-mixtures. 

Three ion-exchange chromatographic separations examined (1) Dionex ASM column using a phosphate mobile phase, (2) an AS 16 column with hydroxide eluent and (3) an AS7 column with nitric acid mobile phase... 

For the separation of cations, a cation exchange column of low capacity is used in conjunction with either a conductivity detector or another type of detector. With a conductivity detector, a dilute solution of nitric acid is typically used for separation of monovalent cations, and a solution of an ethylenediammonium salt is used for separation of divalent cations. Because both of these eluents are more highly conducting than the sample cations, the sample peaks are negative relative to the background (decreasing conductivity). 

Figure 2.1. Separation of alkali-metal cations and ammonium cation on a low-capacity cation exchange column with a conductivity detector. Eluent 1.0 mM nitric acid. Column 350 X 2.0 mm packed with 0.059 mequiv/g calion-cxchangc resin.

The selectivity of low capacity cation columns for monovalent ions can be adjusted by the addition of an organic modifier to the eluent. Using a nitric acid eluent of pH... 

For example, if a dilute nitric acid eluent is used and sodium and potassium sample ions are to be separated, the following reactions take place in the suppressor unit ... 

Normal IC separations rely on a high-pressure eluent pump, injection valve, column and detector. However, a novel method for speciation was developed by Gjerde and Wiederin [4], in which a low-pressure column, valveless injection method was employed. The system configuration is shown in Fig. 11.1. An example with this type of IC to perform a separation of Cr(III) and Cr(IV) is shown in Fig. 11.2. Nitric acid eluent is acceptable in this case because it does not oxidize Cr(III). The separation method is anion exchange, so Cr(III) is unretained and Cr(IV) is eluted by the nitrate... 

Figure 11.2. Separation of Cr(IIl) and Cr(VI) by valveless IC and JCP-MS detection. The separation is affected by both the volume of sample introduced to the column and the speed of the peristaltic pump. The eluent was 0.35 % (w/w) nitric acid adjusted to pH 1.6 with ammonium hydroxide. The column is a low-capacity anion exchanger ANX3202 with dimensions of 3.2 x 20 mm. Detection limits for Cr(IlI) and Cr(Vl) are both <0.1 ppb. Courtesy of Transgenomic, Inc., Omaha, NE.

Plutonium trifluoride. Plutonium trifluoride can be converted directly to plutonium metal, or it is an intermediate in the formation of PUF4 or PUF4 -PUO2 mixtures for thermochemical reduction, as described in Sec. 4.8. The stabilized Pu(III) solution, produced by cation exchange in one of the Purex process options for fuel reprocessing, is a natural feed for the formation of plutonium trifluoride, as is shown in the flow sheet of Fig. 9.9 [03]. A typical eluent solution from cation exchange consists of 30 to 70 g plutonium/liter, 4 to 5 Af nitric acid, 0.2 Af sulfamic acid, and 03 Af hydroxylamine nitrate. The sulfamic acid reacts rapidly with nitrous acid to reduce the rate of oxidation of Pu(III) to about 4 to 6 percent per day. Addition of ascorbic acid to the plutonium solution just before fluoride precipitation reduces Pu(IV) rapidly and completely to Pu(III). 

Figure 4.39. Single-line two-valve FIA system for on-line preconcentration as used for the determination of trace amounts of metal ions. A large sample volume is injected into the carrier stream by means of valve S and propelled into a small column containing a cation exchanger (Chelex-100), which effectively retains the metal ions. Hence no signal is recorded by the detector. Next, a small volume of eluent (E, nitric acid) is injected by the second valve, the metal ions on the column being eluted into a small zone that upon transport to the detector gives rise to a signal before the sample is led to waste, W.

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