Separation trifluoracetic acid

Figure 5.5 Tryptic digest of extracellular superoxide dismutase separated by (a) reversed-phase HPLC, using 0.1% (v/v) trifluoracetic acid in an acetonitrile/water gradient, and (b) CZE, using a 100 mM phosphate buffer, pH 2.5. (Reprinted from Ref. 15 with permission.)...

Due to the low volatility and thermostability, enantiomers of chiral drugs are basically resolved as their more volatile and stable derivatives obtained by the interaction of parent drugs with isocyanates, trifluoracetic acid, phosgene, etc. Sometimes, derivatization can be performed not only in order to meet the volatility and stability requirements but also in order to improve the chemo- and enantioselectivity of separation. Certainly, a derivatization with a chiral derivatizing reagent and the separation of the covalent diastereomeric compounds on an achiral CSP is also possible, but is essentially not used. 

Tricyclic antidepressants were analyzed by Vallano et al. [179] via an MIP-CEC separation. In this separation, doxepin, imipramine, amitriptyline, trimipramine, and clomipramine were separated from the template molecule nortriptyline (Figure 5.22). The capillary inner diameter and total length were 100 pm and 33 cm, respectively, and the total length of the monolithic bed was 22.5 cm. The eluent was 92 2 ACN 10 mM sodium acetate pH 3.0 to which 0.02% trifluoracetic acid and 0.015% triethylamine (TEA) (v/v) was added. A constant applied voltage of 30 kV was utilized. 

FIGURE 5.22 MIP-CEC separation of a simulated combinatorial library consisting of several tricyclic antidepressants. Conditions capillary i.d. 100 ji.m Ltot 33 cm Lbed 22.5 cm elnentACN lOmMNa acetate pH 3.0 (98 2) with 0.02% trifluoracetic acid and 0.015% TEA (v/v) voltage -E30 kV constant injection -P2 kV, 2 s column temperature 50 C. (Reprinted from VaUano, P.T. and Remcho, V.T., J. Chmmatogr. A, 887, 125-135, 2000, with permission from Elsevier.)... 

In LC-NMR, separation is usually performed on an RP CIS column and broad acetonitrile or methanol gradients are applied, using D2O instead of water, and trifluoracetic acid to improve resolution of polyphenols. UV spectra are recorded for all constituents with the aid of a photodiode array detector. However, it should be taken into consideration that chemical shifts in an RP solvent will slightly differ from those recorded in standard deuterated solvents. 

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