Eluents sodium nitrate

With the temperature increase in the range 298-333K, there is observed the increase in Au(III) ions sorption compared to that of Pd(II) ions. The sodium nitrate(III) and thiourea solutions were used as eluents. Sodium nitrate(III) (2 M, pH 4.7) desorbs 75% of Pd(II) practically not washing out Au(III) from the ion exchanger, whereas thiourea (0.5 M, [H ] 0.1 M) enables almost quantitative recovery of gold(III) containing trace amounts of palladium (II) ions. 

Sanchez et al. observed that the increase of temperature from 298 to 333 K resulted in an increase in the sorption of Au ions compared to that of Pd " ions. Thiourea and sodium nitrate were used as eluents. Sodium nitrate (2 mol pH 4.7) desorbed 75% of Pd and did not elute Au, but thiourea (0.5 mol L , [H ] = 1.0 mol L ) allowed for almost complete recovery of Au containing trace amounts of Pd ions. ... 

For some nonionic, nonpolar polymers, such as polyethylene glycols, normal chromatograms can be obtained by using distilled water. Some more polar nonionic polymers exhibit abnormal peak shapes or minor peaks near the void volume when eluted with distilled water due to ionic interactions between the sample and the charged groups on the resin surface. To eliminate ionic interactions, a neutral salt, such as sodium nitrate or sodium sulfate, is added to the aqueous eluent. Generally, a salt concentration of 0.1-0.5 M is sufficient to overcome undesired ionic interactions. 

Even the elution volume of acetonitrile was not constant in these eluents and varied from 1.25 to 1.95 ml. The volumes of ionized sodium nitrate (e) and 2,4-dinitronaphthol (d) were smaller than the exclusion limit (1.0 ml) of this column. The dramatic change for 2,4-dinitronaphthol in Figure 3.9A indicates that the volume depended strongly upon the ratio of eluent components.5... 

Figure 3.9 Elution volumes (ml) of alternative void volume markers. Column, 5 im octadecyl-bonded silica gel, 15 cm x 4.5 mm i.d. eluents A and B, 10-90% aqueous acetonitrile, eluents C and D, 10-90% aqueous acetonitrile containing 50 mMphosphoric acid flow rate, 1 ml min temperature, 30 °C detection, UV 210 nm and refractometer. Sample a, acetonitrile b, methanol c, fructose d, 2,4-dinitronaphthol e, sodium nitrate, f, tetrahydrofuran g, deuterium oxide, and h, uric acid.

Eluent Dissolve 35.0 g of sodium nitrate and 1.0 g of sodium azide in 100 mL of HPLC-grade water. Filter through a 0.45- im filter into a 4-L flask. Dilute to volume with HPLC-grade water. Degas by applying an aspirator vacuum for 30 min. The resulting eluent is 0.1 IV sodium nitrate containing 0.025% sodium azide. 

Chloride, bromide, and iodide ean be separated on a strongly basic anion exchanger, using sodium nitrate solutions of variable concentration as eluents. Bromide can be separated from many anions on the anion-exchanger Dowex 1 [4]. 

Figure 7.7 Effect of eluent ionic strength on the separation of anionic polymers (polyacrylic add sodium salt) in aqueous sodium nitrate solution. Sodium nitrate concentrations A, 0 B, O.OIM C, 0.025M Z), 0.05M E, 0.1M. Separations were performed on TSKgel GMPW (two 600 x 7.5 mm LD. columns) at a flow rate of ImLmin" and 25°C [15].

Aqueous salt solutions are corrosive to stainless steel, especially at low pH. When aqueous acetic acid solutions are used as eluent, attention must therefore be paid to corrosion of the HPLC system. However, some salts, such as sodium sulphate, sodium nitrate, sodium acetate and sodium perchlorate, cause little corrosion of stainless steel even at low pH. Accordingly, these salts are a good choice for use together with acetic acid. Salts containing... 

The area of the induced salt peak depends on the charge and the concentration of the sample ion. Kadokura et al. [ref. 33] have recently attempted to evaluate quantitatively the area of the induced peak on the basis of the Donnan equilibrium. They assumed that chloride, sulphate and naphthalene-1,3,6-trisu1phonate anions used as sample ions are excluded by Sephadex G-10 gel, but not the eluent anion (nitrate ion) and the common cation (sodium ion), and demonstrated that the amount of the eluent colons (in moles) excluded from the sample zone, can be related to the total amount of sample ions injected (in moles), Q, by the following equation... 

Note that in the many cases where sodium nitrate is shown, many workers have used acetate, sulfate, sodium chloride, etc. Sodium nitrate tends to minimize ionic interferences very consistently for neutral and anionic compounds. These various eluents are used because the methacrylate-based gel packing for aqueous GPC has overall anionic charges, which can cause ion exclusion for anionic samples and ion adsorption for cationic samples if run in water alone. 

Strong eluents such as sodium nitrate may be employed. The resulting chromatogram is displayed in Figure 3.171. For the analysis of herbicides lacking a chromophore such as endothall, 7-oxabicyclo[2,2,l]-heptane-2,3-dicarboxylic acid, anion-exchange chromatography with subsequent conductivity detection provides an alternative to RPLC. 

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. 

Fig. 1. Simultaneous separation and detection of anions and cations on a latex agglomerate column. Column Dionex HPIC-CS5 cation exchange column (250X2 mm) with precolumn HPIC-CG5 (50 X 4 mm) eluent 0.5 mM copper sulfate, pH 5. 62 flow rate 0.5 ml/min sample volume 20 gl containing 0.1 m M of each ion detection two potentiomet-ric detectors equipped with different ion-selective electrodes in series. Peaks (1) chloroacetate, (2) chloride, (3) nitrite, (4) benzoate, (5) cyanate, (6) bromide, (7) nitrate, (8) sodium, (9) ammonium, (10) potassium, (11) rubidium, (12) cesium, (13) thallium. Reprinted with permission from [10].

Figure 2. Ion chromatographic separation of a series of anions on polymer-based column with adsorbed decyl-2.2.2 using gradient capacity from sodium hydroxide to lithium hydroxide aqueous eluent. Anions 1) fluoride 2) acetate 3) chloride 4) nitrite 5) bromide 6) nitrate 7) sulfate 8) oxalate 9) chromate 10) iodide 11) phosphate 12) phthalate 13) citrate 14) thiocyanate (from refs. 13,14)...

Figure 9. Analysis of anions and cations in river water using tartaric acid/18-crown-6/methanol-water eluent with a carboxylated polyacylate stationary phase in the protonated form. Ions 1) sulfate 2) chloride 3) nitrate 4) eluent dip 5) unknown 6) sodium 7) ammonium 8) potassium 9) magnesium 10) calcium (from ref. 80)...

Van Os et al. [41] achieved complete separations in 6min of l-30mg L 1 concentrations of bromide, chloride, nitrite, nitrate and sulphate using a Zipax SAX separation column, with eluent suppression and electrical conductivity detection [42], The necessary high pressure packing techniques for packing the separation column have been described [43], With sample pieconcentration, detection limits were reduced to about 5pg L 1 but calibration graphs for chloride and nitrate were not linear. Sodium adipate and 1.410 3M disodium succinate are used as eluants, both at pH7. 

An eluent composition of 2.0m mol L 1 sodium bicarbonate and 1.5m mol L 1 sodium carbonate was found to elute arsenate about midway between nitrate and sulphate. Selenite eluted between chloride and nitrate in an eluent that was 3.0m mol L 1 in sodium bicarbonate and 2.0m mol L 1 in sodium carbonate. 

Oikawa and Saitoh [89] reported studies of the application of ion chromatography to the determination of fluoride, chloride, bromide, nitrite, nitrate, sulphate, sulphite and phosphate ions in 3 ml samples of rainwater. The results show that the most suitable eluent for this purpose is 2m mol L 1 sodium carbonate/5m mol L 1 sodium hydroxide. The reproducibility of the determination was satisfactory for standard solutions of all the ions except nitrite. This problem was solved by preparing standard and sample solutions with the same composition as the eluent. 

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