Eluents heptafluorobutyric acid

If polar sequences or short phosphopeptides fail to bind to the stationary phase upon loading, the acetonitrile content of the eluent could be reduced to 3%. A further decrease is not possible for standard Ci8-columns, as the stationary phase could collapse reducing the loading capacity and the reproducibility. Instead, TFA could be replaced by the more hydrophobic ion-pair reagent HFBA (heptafluorobutyric acid), or a stationary phase with a special coating compatible with pure aqueous eluents could be used (e.g., Aqua-column from Phenomenex). 

Figure 5.2 Separation of short-chain fatty acids on lonPac ICE-AS1. Eluent 0.4mmol/L heptafluorobutyric acid flow rate 1 mL/min detection suppressed conductivity injection...

Figure S.3 Separation of carboxylic acids and hydroxycarboxylic acids on lonPac ICE-AS6. Eluent 0.4 mmol/L heptafluorobutyric acid flow rate 0.4 mL/min detection suppressed conductivity injection volume 50 pU peaks 5mg/L oxalic acid (1), lOmg/L tartaric add (2), 15mg/L citric acid (3), 20mg/L malic add (4),...

Figure 8.80 Separation of underivatized amino acids on a 2.2 pm Acclaim PA2 with charged aerosol detection. Column dimensions 250 mm x 2.2 mm i.d. column temperature 20 °C eluent (A) 0.4% heptafluorobutyric acid -1-0.02% TFA in water and (B) 0.1% TFA in MeCN 1% B for 1 min isocratic, to 5% B in 2 min, and then to 40% B in 7 min flow rate ...

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