Anion-exchange gradient separations

FIGURE 8.13 Total ion current chromatogram for a UHP-RPLC-MS separation of one anion exchange fraction (fraction numher 6 from the 30-min anion-exchange gradient). 

HPLC measurement of CDT is routinely used in hospital and research laboratories as a way to detect chronic alcohol misuse. The first HPLC method for the quantification of iron-saturated tiansferrin glycoforms was introduced in 1993,and was based on anion-exchange chromatographic separation of the different glycoforms by salt gradient elution followed by photometric detection. Since then, several variations of the original method have been published ,44 8 number of commercial HPLC assays for CDT have been introduced. ... 

There workers reported 19 c, values for the anion-exchange gradient elution separation of ovalbumin (M- 44,000), while varying experimental conditions widely column lengths of 7.5 and 15 cm, 30 s to 3 min, and 0.25 F 2 ml/min. A value of Z 8.8 was obtained using the data from Fig. 11 and the approach summarized in Table VI, permitting the prediction of (T, values (as in Table VIII). Good f reement was observed (27), with iLr-1.07 and SD- 0.11. 

Purine nucleotides were determined by an anion-exchange gradient HPLC method (6). This method separates all major purine nucleotides as well as the ribonucleotide from the deoxyribo-nucleotide form. 

Figure 10.218 Separation of inorganic and organic acids in beer by anion-exchange chromatography. Separator column lonPac AS11-HC-4pm column dimensions 250 mm x 2 mm i.d. column temperature 30 °C eluent KOH (EG)/MeOH gradient 1 mmol/L KOH with 2% (v/v) MeOH isocratically for 8 min, step to 10% (v/v) MeOH in 0.1 min, 1-15 mmol/L KOH with 10% (v/v) MeOH in lOmin, 15-30mmol/L KOH with 10% (v/v) MeOH in 10 min, and...

Last but not least, milk caseins can also be separated on a suitable anion exchanger. The separation of caseins from bovine milk in Figure 10.240 on ProPac SAX with a mixture of urea, 2-mercaptoethanol, imidazole, and NaQ as an eluent is clearly superior to a conventional separation on a wide-pore reversed-phase column, no matter whether an acetonitrile or an isopropanol gradient is used. 

Figure 10.342 Separation of various metaboiic intermediates by anion-exchange chromatography. Separator column lonPac AS11 eluent NaOH gradient 2-12 mmol/L in ISmin, to...

Fig. 6.14. Gradient cation-exchange (A) and anion-exchange (B) separation of the lanthanides. Detection post-column reaction using PAR, photometric detection at 520 nm, 0.5 AUFS. Sample 10 ppm each metal, 50 /il sample volume. Note Yb(III) and Lu(III) co-eluted for the anion-exchange separation. (Reproduced with permission from ref [29].)...

Figure 4. Separation of ribonucleoside monophosphofic acids. Conditions 250-cm anion exchange column gradient, 0.01M KHgPO containing HsPOi, (pH 2.6) to 0.15M KHiFO in 30 min column tempera-ture, 70 C detector, UV at 254 nm. 1, cyti-dine-S -monophosphoric acid 2, uridine-5 -monophosphoric acid 3, adenosine-5 -mon-ophosphofic acid 4, inosine-5 -monophosphoric acid 5, 3, 5 -cyclic adenosine mono-phosphoric add 6, guanosine-5 -monophosphoric acid (36).

Organic carboxylic acids are commonly found in foods, in the adipate process stream, and as pollutants. Fatty acids are the lipophilic portion of glycerides and a major component of the cell membrane. Phenols are widely used in polymers, as wood preservatives, and as disinfectants. Chloro-phenols such as 4-chlorophenol, two isomeric dichlorophenols, 2,4,6-tri-chlorophenol, three isomeric tetrachlorophenols, and pentachlorophenol were separated on a Dowex (The Dow Chemical Co. Midland, MI) 2-X8 anion exchange resin using an acetic acid-methanol gradient.138... 

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