Eluant phthalic acid

The copper phthalate eluant was prepared by mixing a solution of cupric acetate with an excess of potassium hydroxide and filtering the resulting cupric hydroxide precipitate. The cupric hydroxide precipitate was then mixed with an equimolar amount of phthalic acid and heated gently overnight to produce copper phthalate. 

Polyspher IC AN-1 from Merck AG (Darmstadt, Germany), consisting of a hydrophilic polymethacrylate packing with a particle diameter of 12 pm, exhibits a similar selectivity. Depending on the type of application, this column can be operated with eluants based on phthalic acid, p-hydroxybenzoic acid, tartaric acid, oxalic acid, or boric acid. Figure 3-16 shows a typical chromatogram obtained with a phthalic acid eluant. Under these chromatographic conditions (pH 4) orthophosphate elutes as a monovalent anion ahead of chloride. 

Fig. 3-16. Separation of various inorganic anions on Polyspher 1C AN-1. - Column temperature 35°C eluant 1.5 mmol/L phthalic acid -t 1.38 mol/L Tris + 0.3 mol/L H3BO3, pH 4.0 flow rate 1.3 mL/min detection direct conductivity injection volume 20pL solute concentrations 10 mg/L each of orthophosphate (1), fluoride (2), chloride (3), nitrite (4), bromide (5), nitrate (6), and sulfate (7).

Fig. 3-51. Separation of various inorganic anions on a Vydac 300 1C 405 silica-based anion exchanger. - Eluant 1.5 mmol/L o-phthalic acid (pH 8.9) flow rate no specification detection direct conductivity solute concentrations 5 mg/L fluoride (1), carbonate (2). 1 mg/L chloride (3), 1.5 mg/L nitrite (4), 3 mg/L bromide (5), 2.5 mg/L nitrate (6), 3 mg/L each of orthophosphate (7) and sulfate (8).

With the Metrosep Anion Dual 1 (see Fig. 3-17 in Section 3.4.1) and a phthalic acid eluant, such separation is achieved in about 20 minutes. 

Fig. 7-8. Amperometric detection of nitrite, thiosulfate, and iodide on a carbon paste electrode. — Separator column Supersep Anion eluant 3.3 mmol/L phthalic acid — acetonitrile (90 10 v/v), pH 4.5 with Tris ...

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