Eluents acid

The elution order of metal ions reported in Table 5.5 is similar to that reported earlier by Strelow and Sondorp [8] with perehloric acid eluent and gel resins of high exchange capacity. Strelow and co-workers noted anion-complexing effects on elution orders in several cases when eluent acids other than perchloric acid were used. 

Several other organic acids have been investigated as eluents in ion chromatography [14]. One objective was to find an eluent acid that is not adsorbed by the resin matrix and that attains equilibrium faster than benzoic acid. 

Table 6.9 lists the relative retention time of the chloride sample anion with the acid eluents chosen for this study. The adjusted retention time of chloride decreases as the retention time for the eluent anion increases and it also decreases as the amount of ionization of the eluent increases. The most satisfactory separations were obtained with either nicotinic acid or succinic acid as the eluent acid. 

The pH of the eluent acid should also be expected to affect the detection sensitivity for various anions. For anions of strong acids (chloride, bromide, nitrate, etc.) the detection sensitivity should be excellent because the sample anion and the highly... 

The lonPac CS12A cation exchanger can also be used to separate quaternary ammonium compounds (Figure 4.85). The chromatographic conditions are very similar to those described in Figure 4.84. Because quaternary ammonium compounds have a much larger carbon backbone, hydrophobic interactions with the stationary phase are so strong that an increase in eluent acid concentration does... 

Fig. 28. Selectivity hexagons neutral and acidic aromatic compounds in unbuflFered eluent/acidic phosphate buffer .

The concentrations of benzoic acid, aspartame, caffeine, and saccharin in a variety of beverages are determined in this experiment. A Gig column and a mobile phase of 80% v/v acetic acid (pH = 4.2) and 20% v/v methanol are used to effect the separation. A UV detector set to 254 nm is used to measure the eluent s absorbance. The ability to adjust retention times by changing the mobile phase s pH is also explored. 

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. 

Magnesium, calcium, barium, and strontium can also be deterrnined by ion chromatography with y -phenylenediamine in perchloric acid as the eluent. Ion chromatography by conductimetric detection has been described, and appHcations to environmental waters have been discussed (1,22—23). 

The influence of NH., and CO, on the chromatographic behaviour of benzoic acid and its derivatives (o-, m-, p-hydroxybenzoic, nitrobenzoic, aminobenzoic, chlorobenzoic acids) was studied. The work was carried out by means of upgoing TLC on Sorbfil plates. Isopropanol- and ethyl acetate-containing water-organic eluents were used as mobile phases in the absence or presence of gaseous modifiers in the MP. The novel modification of TLC has been found to separate benzoic acids with different values of their dissociation constants more effectively than water-organic mobile phases. 

APPLICATION METHANOL ELUENT RP-HPLC ANALYSIS FOR ESTERS OF 4-AMINOBENZENTHIOSULFINIC ACID AT PROCESS OF THEIR SYNTHESIS... 

The esters of thiosulfinic acid R -SO,-S-R are used as fungicides and antibacterial prepai ations. These compounds have similar stiaicture fragments to allicin - natural insecticide from garlic with following structure (CH =CH-CH ),[SO-S] (http //www.ALLICIN.com). For deter-mination of ethyl S-ester of 4-aminobenzenthiosulfinic acid (esulan) in the ointment RP-HPLC was proposed [1] with acetonitrile water=30 70 as eluent. For seai ching bioactive compounds the synthesis of new esters of thiosulfinic acid is perspective that was confirmed by results of recent studies as instance [2]. Therefore requirements ai e existed for investigation HPLC sepai ations of these substances. 

With eluent MeOH H O = 40 60% w (flow rate -1 ml/min) full sepai ation was achieved within acetylated and non-acetylated on amino group of eight thioesters of 4-aminobenzenthiosulfinic acid with retention in next order for R - = -CH3, -C,H3,-CH,-CH=CH, -C3H3by RP-HPLC on Spherisorb-ODS-2 (250x4,6 mm). The chromatograms were obtained at 254 and 289 nm. Retention was generalized by In = In - S-(p (cp - MeOH volume pai t in range near 0.4-0.6) as shown in Fig. 

Anthrarufin [l,5-dihydroxy-9,10-anthraquinone] [117-12-4] M 240.1, m 280 (dec), pKj 9.90, pK 11.05. Purified by column chromatography on silica gel with CHCl3/Et20 as eluent, followed by recrystn from acetone. Alternatively recrystd from glacial acetic acid [Flom and Barbara J Phys Chem 89 4489 1985]. 

The well-dried chromatogram (1 h at 105°C if acidic or basic eluents have been employed) is immersed in the dipping solution for 1 s or homogeneously sprayed with the spray solution and then dried in a stream of cold air. Acids yield blue zones on a colorless or pale blue background [1] which gradually darkens. 

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