Eluents pyridine-2,6-dicarboxylic acid

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. 

Fig. 8-22. Analysis of chromium(VI) in a scrubber solution from the flue gas desulfurization. — Separator column IonPac CS5 eluent 0.002 mol/L pyridine-2,6-dicarboxylic acid + 0.002 mol/L Na2HP04 + 0.01 mol/L Nal + 0.05 mol/L NH4OAC + 0.0028 mol/L LiOH flow rate 1 mL/min detection photometry at 520 nm after reaction with 1,5-diphenylcarbazide injection 50 pL sample (1 10 diluted).

Among many ligands used for simultaneous ion chromatography of metals, the most common eluents used are oxalic acid, tartaric acid, citric acid, 4-(2-pirydylazo)resorcinol (PAR), pyridine-2,6-dicarboxylic acid (PDCA), a-hydroxyi-sobutyric acid (HIBA), 1,2-diaminocyclohexanetetraacetic acid (DCTA), diethylenetriarninepentaacetic acid (DTPA), and ethylenediaminetetraacetic acid (EDTA). 

Cation exchangers based on PBDMA-coated silica are offered by a number of companies. Metrohm (Herisau, Switzerland), for example, offers two columns under the trade names Metrosep Cl and C4. The 5 pm Metrosep Cl is considered to be the high-performance column for the simultaneous analysis of mono-and divalent cations with an analysis time of less than 20 min. It can also be used for the separation of various amines, which are typically eluted with a nitric acid eluent. Figure 4.41 shows an example chromatogram obtained under standard chromatographic conditions with an eluent mixture of tartaric acid and pyridine-2,6-dicarboxyiic acid (PDCA) (dipicohnic acid). Under these chromatographic conditions, calcium elutes ahead of magnesium, followed by strontium and barium. This unusual retention behavior can be attributed to the complex-ing properties of pyridine-2,6-dicarboxylic acid. With a pure tartaric acid eluent. 

Figure 4.42 Simultaneous separation of alkali metals, alkaline-earth metals, and ammonium on Metrosep C4. Column dimensions 250 mm x 2 mm i.d. eluent 1.7mmol/L nitric acid-l-0.7 mmol/L pyridine-2,6-dicarboxylic acid flow...

Figure 8.51 Analysis of chromium(VI) in a flue gas scrubber solution. Separator column lon-Pac CS5A eluent 2 mmol/L pyridine-2,6-dicarboxylic acid + 2 mmol/L Na2HP04 +10 mmol/L Nal +50 mmol/L NH4OAC flow rate ...

Figure 10.9 Cation analysis of a rain water sample. Separator column Metrosep Cation 1 -2 eluent 4 mmol/L tartaric acid +1 mmol/L pyridine-2,6-dicarboxylic acid flow rate 1 ml/ min detection nonsuppressed conductivity ...

Figure 10.63 Determination of iron(lll) and iron(ll) extracted from soil with 0.5 mol/L HCI. Separator column lonPac CS5A eluent 6mmol/L pyridine-2,6-dicarboxylic acid/...

Other common transition metal corrosion products typically monitored at various sites within the plant include iron, copper, nickel, zinc, and chromium. More than 80% of BWR plants analyze for iron, nickel, copper, and zinc in reactor water, and nearly all of the BWR plants determine these metals in feed water. In addition, zinc is also an additive used in many plants to control the shutdown radiation dose rate. Nickel and chromium are corrosion products in BWR plants fi-om stainless-steel piping. The best selectivity and sensitivity for achieving low to submicrogram/Liter detection limits for transition metals can be obtained by separating transition metal complexes using pyridine-2, 6-dicarboxylic acid (PDCA) or oxalic acid as chelators in the eluent, followed by postcolumn derivatization with 4-(2-pyridylazo)resorcinol (PAR) and absorbance detection at 520 nm (see Section 8.2.1.2). This approach was successfully used to determine trace concentrations of iron, copper, nickel, and zinc in BWR and PWR matrices [197]. Figure 10.113 compares the chromatograms from the... 

Figure 10.131 Trace analysis of metals in a high-purity water sample. Separator column lonPac CS5A concentrator column lonPac CG2 eluent 6 mmol/L pyridine-2,6-dicarboxylic acid + 86 mmol/L LiOH flow...

Figure 10.224 Determination of alkali and 10 1 detection nonsuppressed conductivity alkaline-earth metals in a red wine. Separator sample Italian red wine diluted 1 50 with column Metrosep Cation 1-2 eluent 4mmol/L deionized water peaks 95mg/L sodium (1), tartaric acid -l-1 mmol/L pyridine-2.6-dicarboxylic 822mg/L potassium (2), 306mg/L caldum (3), acid flow rate 1 mL/min injection volume and 722 mg/L magnesium (see [333]).

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