Cation exchange columns Dionex

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].

Shown in Fig. 2.8 is a schematic diagram of the Dionex ion exchange liquid chromatograph used by Smee et al. [40], The instrumentation consists essentially of a low capacity anion exchange column, the separator , a high capacity cation exchange column, the suppressor and the detection system, a high sensitivity conductivity meter and recorder. 

Dionex Corp., Ion pac CS12A cation exchange column. Fig. 6,1995. 

Most environmental samples require some pretreatment, usually in the form of filtration and centrifugation, before these are injected via a sample loop. lEC separation of organic acids is achieved on cation exchange columns which are characterized by their particle diameter, substrate crosslinking, ion exchange capacity, type of functional group, and hydrophobicity. The most commonly used columns are comprised of fully sulfonated, crosslinked divinylbenzene/polystyrene copolymers (e.g., HPICE-AS6 or -ASl, Dionex). However, a comparison smdy found other columns to be equally as effective for organic acid separation. Unmodified silica gel columns... 

FIGURE 28-24 Typical applications of ion chromatography. (a) Separation of anions on an anion-exchartge column. Eluent 0.0028 M NaHCOj to 0.0023 M Na2C03. Sample size 50 pL. (b) Separation of alkaline earth ions on a cation-exchange column. EluenI 0,025 M phenylene-diamine dthydrochlohde to 0,0025 M HCI. Sample size 100 mL, (Couriesy of Dionex Corp., Sunnyvale, CA.)... 

This benchmark publication was followed by a series of developments that continues to this day in the evolution of IC as a trace determinative technique. The Dionex Corporation was formed out of these developments from Dow Chemical in the mid-1970s and this company has been quite an innovator in the manufacture of instrumentation for suppressed IC. From the earlier model such as the 10 to the 20001 to the DX 500 from the cation-exchange column to the hollow-fiber cation suppressor to the micro-membrane cation suppressor to the self-regenerate cation suppression for anion analysis and now to their just add water slogan, Dionex Corporation has made considerable advances in IC technology. A nonsuppressed form of IC also developed during the 1970s. To quote from the author s abstract of this benchmark paper (97) ... 

In contrast to surface-sulfonated phases, latex cation exchangers exhibit a significantly higher chromatographic efficiency. Examples of Dionex latex cation-exchange columns are given in Table 9. 

Table 4.10 Specifications of Thermo Scientific Dionex ProPac cation-exchange columns.

Table 4.11 Specifications of Dionex ProSwift cation-exchange columns.

Valproic acid was determined in tablets and plasma using ion-chromatography [29], The extract was injected onto a column (6.5 cm x 6 mm) of Dionex ICE separator resin fitted with a guard column of Aminex cation exchange resin and operated with aq. 0.5 mM C02 as mobile phase (0.7 mL/min) and conductivity detection. For tablets, the calibration graph was rectilinear for 0.2-25 pg/mL with limit of detection of 50 pg/mL. For plasma, the response was linear for 50-200 pg/mL and limit of detection was 2 pg/mL. 

Improvements in separations ability offered by the Dionex HPIC-CS5 column, which exhibits both anion and cation exchange capacity, have allowed the determination of ten metal ions in a single injection with a pyridine-2,6-dicarboxylic acid (PCDA) eluent (Fig. 2.3). The post-column reagent used in the detection scheme was 4-(2-pyridylazo) resorcinol. 

Al, Fe Cation exchange Dionex CS2 resin Post column derivitisation with Chrome Azurol S-acetyl methyl ammonium bromide (TritionX-100) [23]... 

The properties and performance of a commercial weak-acid resin column (Dionex CS12) have been described [41]. The substrate is a highly cross-linked, macroporous ethylvinylbenzene-divinylbenzene polymer with a bead diameter of 8 pm, a pore size of 6 nm, and a specific surface area of 3(X) m /g. In a second step, this substrate was grafted with another polymer containing carboxylate groups. The exchange capacity is listed as 2.8 mequiv/column for a 250 mm x 4 mm i.d. column. With this column, simple eluents such as hydrochloric or methanesulfonic acid can be used to separate mono- and divalent cations rapidly and efficiently under isocratic conditions. 

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