Absorbance anions

FIGURE 6 Analysis of UV-absorbing anions and organic acid is possible with a 70mM phosphate buffer at pH 2.5. 

Mullins and Kirkbright (38) reported separation of the UV absorbing anions iodate, nitrite, bromide, nitrate and iodide using a micellar mobile phase containing hexadecyltrimethylammonium chloride above its CMC. Figure 2 illustrates this separation with two different concentrations of micellar reagent. Increasing the concentration of hexadecyltrimethylammonium chloride decreases the retention time (38) on the column. 

Figure 10.12 Indirect photometric analysis performed at 220 nm with an eluent containing citric acid. The positive peaks are due to the UV absorbing anions, nitrite (3), nitrate (4) and iodide (6), whereas the negative responses arise from the non-UV absorbing anions, phosphate (1), chloride (2) and sulphate (5).

High doses of sodium penicillin can cause urinary potassium loss, presumably by acting as a non-absorbable anion in the distal tubule (30). Apparently by analogous mechanisms a variety of semisjmthetic peniciUins, including carbenicUhn, cloxacUhn, mezlocillin, nafcUhn,... 

In a simulation of 34,284 atoms in a periodic box employing a nonpolarizable force field, Liu et al. studied the IL [C4mim][N03]/rutile (110) interface. Anions were found to segregate and tightly bind on the surface. The orientation of the cations was modulated by the absorbed anions [109],... 

In practice, corrosive, reducing and highly UV-absorbing anions are avoided, the most common buffers being phosphate, borate, nitrate and perchlorate, with sulfate, acetate and citrate occasionally being considered. 

Figure 10.3. The electrophoretic mobilities of common UV-absorbing anions and analyte anions. From Ref. [3],...

Indirect UV detection is a common technique which has been applied to the analysis of cations and anions. A UV-absorbing anion plus an electroos-motic flow modifier is added to the electrolyte. The displacement chromophore permits indirect photometric detection. Optimum separations can be achieved by choosing an electrolyte anion which has a mobility similar to the ions of interest. Some investigators have used conductivity detection, while others have used indirect laser-induced fluorescence for anion detection. Detection of the nonfluorescence analyte is obtained by charge displacement of the fluorophore (339,340). 

Both PA-300 and NS-100 exhibit mild cationic behavior because of the ex-cess unreacted amino groups present in the barrier layer. One manner in which this is evident is their propensity to absorb anionic surfactants and lose flux... 

Hydrochlorothiazide becomes bound to these non-absorbable anionic exchange resins within the gut, and less is available for absorption. 

M.I. Turnes-Carou, P. Lopez-Mahi a, S. Muniategui-Lorenzo, E. Fernandez-Femandez and D. Prada-Rodriguez, Capillary zone electrophoresis for the determination of light-absorbing anions in environmental samples, J. Ghromatogr. A, 918, 411 21, 2001. 

Connolly, D. Pauli, B. Fast separation of UV absorbing anions using ion-interaction chromatography. J. Chromatogr. A, 2001, 917,353-359. 

Anion exchange resin n. Certain synthetic resins with the property of absorbing anions from aqueous salt solutions. 

Indirect spectral detection requires the use of a strongly absorbing anion in the eluent. Eluents containing molybdate, p-hydroxybenzoate or phthalate have been used successfully. 

The redox properties of conducting heterocyclic polymers like polypyrrole are central to many applications of these materials. For this reason the electrochemistry of thin films of these polymers have received a lot of attention. For use in electrically controlled ion binding and delivery, the general idea is that the heterocyclic conducting polymers have cationic backbones and will incorporate counter anions. Upon reduction of the backbone, the anions will be flushed out. Thus, in principle one can develop devices to absorb anions of interest or to release them in response to an electric current. Our work has been spurred by the possibility of delivering drugs with a rate controlled by the current. 

With Metrosep A Supp 8 Metrohm offers a special ultrahigh-capacity ion exchanger for the separation of UV-absorbing anions such as bromide, nitrite, and nitrate in brine solutions utilizing a sodium chloride eluent. 

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