Eluents separation

The preferred solution is CO2 recycling at a pressure of about 40-50 bar, slightly below the typical pressure inside CO2 cylinders stored at ambient temperature. Eluent recycling and condensation at this pressure requires cooling uhlities for a temperature range of 0-5 °C. Under these condihons the solute-eluent separation... 

Oligomer Functional group fn Stationary phase Eluent (separation conditions) Method Ref. 

Fig. 3-53. Separation of halide ions using tyrosine as the eluent. - Separator column IonPac AS4A eluent 0.001 mol/L tyrosine + 0.003 mol/L NaOH flow rate 2 mL/min detection suppressed conductivity injection volume 50 pL.

Fig. 3-61. Separation of inorganic anions using a borate/gluconate buffer as the eluent. - Separator column TSK Gel IC-PW eluent 0.0013 mol/L Na2B407 + 0.0058 mol/L H3B03 + 0.0014 mol/L potassium gluconate/acetonitrile (88 12 v/ v), pH 8.5 flow rate 1.2 mL/min detection direct conductivity injection 100 pL anion standard (5 to 40 ppm) (taken from [66]).

Fig. 3-62. Separation of inorganic anions using potassium hydrogenphthalate as the eluent. — Separator column Waters IC-PAK Anion eluent 0.001 mol/L KHP, pH 7.0 flow rate 2 mlVmin detection direct conductivity injection volume 10 pL solute concentrations 100 ppm each.

Fig. 3-63. Separation of inorganic anions using p-hydroxybenzoic add as the eluent. - Separator column Wescan 269-029 eluent 0.004 mol/L PHBA, pH 8.7 flow rate 1.5 mL/min detection direct conductivity injection volume 100 pL solute concentrations 5 ppm fluoride, chloride, nitrite, bromide, and nitrate, and 10 ppm orthophosphate and sulfate.

Fig. 3-66. Separation of monovalent anions using nicotinic acid as the eluent. — Separator column Wescan 269-031 eluent 0.01 moI/L nicotinic acid flow rate 2.7 mL/min detection direct conductivity injection volume 100 pL solute concentrations 20 ppm azide, 10 ppm formate and fluoride, 20 ppm orthophosphate, 10 ppm nitrite and chloride, 15 ppm bromate (taken from [70]).

Fig. 3-127. Separation of various inorganic anions with an isoconductive eluent. - Separator column Waters IC-PAK Anion eluent see Table 3-23 (eluent switching at the time of injection) detection direct conductivity injection volume 100 pL solute concentrations 1 ppm fluoride (1), 2 ppm carbonate (2) and chloride (3), 4 ppm nitrite (4), bromide (5), and nitrate (6), 6 ppm orthophosphate (7), 4 ppm sulfate (8) and oxalate (9), 10 ppm chromate (10), and molybdate (11) (taken from [135]).

Conductivity detection is the most popular for ion chromatography. Although UV detection is often overlooked, it can be quite powerful. Amperometric detection, for example, offers selectivity and sensitivity, in many cases unsurpassed. The optimum eluent separation pH may not be the optimum pH for detection. An anion may be separated but not detected. This is especially true for some weak acid anions and suppressed conductivity detection. Chapter 4 discusses the use of different detectors for IC. 

Chemically bonded aminopropyl phases have also been successfully employed for the separation of inorganic ions. Leuenberger et al. [31] described the separation of nitrate and bromide in foods on such a phase using a phosphate buffer solution as the eluent. Separations of this kind are limited in terms of their applicability, because they can be applied only to UV-absorbing species. 

Figure 3.68 Selectivity comparison for environmentally relevant anions on lonPac AS21 between a hydroxide and a methyl amine eluent. Separator column lonPac AS21 column dimensions 250 mm x 2 mm i.d. column temperature 30 °C eluent (a) 12.5 mmol/L KOH (EG) and (b) 200 mmol/L methyl amine flow...

Figure 3.114 Removing carbon dioxide from suppressed carbonate eluent. Separator column lonPac AS9-HC column temperature ...

Figure 3.143 Separation of inorganic anions with a phthalic acid eluent. Separator column Shimpack IC-A1 eluent 2.5mmol/L phthalic acid + 2.4 mmol/L tris(hydroxymethyl)amino-methane, pH 4.0 flow rate I.SmL/min ...

Figure 3.145 Separation of anions derived from weak inorganic acids using a strongiy basic eluent. Separator column Wescan 269-029 eluent 4 mmol/L NaOH -i- 0.5 mmol/L sodium benzoate flow rate 1.5ml7min detection indirect conductivity injection...

Figure 3.202 Separation of inorganic anions with an electrolytically generated KOH eluent. Separator column lonPac AS11 eluent ...

Figure 3.203 Trace analysis of inorganic and organic anions with an electrolytically generated KOH eluent. Separator column lonPac AS15 column temperature 30°C eluent KOH (EG) gradient 9 mmol/L isocratically for 7 min and then to 46 mmol/L in 11 min flow rate 1.6mL/min detection suppressed...

Figure 3.204 Gradient elution of inorganic and organic anions with a sodium tetraborate eluent. Separator column lonPac ASM eluent Na2B407 gradient 2 mmol/L isocratically for 6 min and then linearly to 17.5 mmol/L flow rate 1.5 mL/min detection suppressed...

Figure 3.207 Separation of various inorganic anions with an isoconductive eluent. Separator column Waters IC-PAK Anion eluent see Table 3.28 (eluent switching at the time of injection) detection nonsuppressed conductivity injection volume lOOpL peaks 1 mg/L fluoride (1), 2 mg/L each of carbonate (2) and...

Figure 3.291 influence of pH on the retention of G- and T-containing oiigonucieotides in NaCI-based eluents. Separator column DNAPac PA200 base composition AsCsGgTg. 

Figure 10.31 Separation of bromate at trace level in a mineral water sample according to ISO 11206 using a sulfuric acid eluent Separator column Metrosep A Supp 16 column dimensions 100 mm x 4 mm i.d. column temperature 45 °C eluent 100 mmol/L H2SO4...

Figure 10.389 Separation of chloride and sulfate in a denatured bioethanol sample with a carbonate-based eluent. Separator column Metrosep A Supp 5 column dimensions ...

Other elements that show strong adsorption from dilute HCl include many of the transition metals, tin, tellurium, and polonlum. 3 Kraus and Moore have effected the separation of protactinium and uranium by adsorbing them from 8M HCl on a column of Dowex A-1 resin and developing the column with 3.8m HCl. Protactinium appeared first In the eluent, separated from uranium. The uranium fraction contained, however, a fair amount of protactinium tailing. ... 

The mixture (eluent + separated products) is depressurized in an adiabatic, thus isoenthalpic, way. 

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