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Influence of pH on Retention Non-Polar

Influence of pH on Retention Non-Polar. pH 3.0. pH 7.0. RCOOH. RCOO -. C2. C2. Adjust pH to Suppress Ionization. RCOOH pKa = 5.0. Influence of pH on Retention Ion Exchange. pH 3.0. pH 7.0. RCOOH. RCOO -. SAX. SAX. Adjust pH to Ensure Ionization. Anion Exchange. Interference

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Influence of pH on Retention Non-Polar

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  1. Influence of pH on RetentionNon-Polar pH 3.0 pH 7.0 RCOOH RCOO- C2 C2 Adjust pH to Suppress Ionization RCOOH pKa = 5.0

  2. Influence of pH on RetentionIon Exchange pH 3.0 pH 7.0 RCOOH RCOO- SAX SAX Adjust pH to Ensure Ionization

  3. Anion Exchange Interference Elution Analyte Elution Condition Apply Sample 1. Methanol 2. Water or Buffer 2 pH Units Below pKa (500mM H2SO4) 2 pH Units Above Isolate pKa Water or Buffer SAX SAX SAX SAX Homovanillic Acid Rumsby, et. al.

  4. Weak Anion Exchange (NH2) pH 3 pH 7 pH 11 Analyte: Weak Anion, pKa 5.0R-COOHR-COO-R-COO- Sorbent: NH2, pKa 9.8 R-NH3+ R-NH3+ R-NH2 Analyte: Strong Anion R-SO3- R-SO3- R-SO3- Sorbent: NH2, pKa 9.8 R-NH3+ R-NH3+ R-NH2

  5. Strong Anion Exchange (SAX) pH 3 pH 7 pH 11 Analyte: Weak Anion, pKa 5.0R-COOHR-COO-R-COO- Sorbent: SAX R-NR3+ R-NR3+ R-NR3+ Analyte: Strong Anion R-SO3- R-SO3- R-SO3- Sorbent: SAX R-NR3+ R-NR3+ R-NR3+

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