Hi jcwagner,
jc wagner askedDoes anyone know what is the use of acidic or basic additives (DEA or TFA etc) in normal phase chiral chromatography?
This website may help answer these questions:
http://chiraltech.com/global-faqs/FAQ #4: To aid in analyte solubility in the event that they are not soluble in hexane-alcohol based eluents.
From FAQ #4, " If your sample is an acid salt of a base, then (the) addition of 0.1% DEA to the sample solvent may help solubility by converting the material to the free base, which usually is more soluble. Conversely, If your sample is a salt of an acid, then (the) addition of 0.1% trifluoroacetic acid may improve solubility."
FAQ #9: For acidic and basic analytes, to allow for better interaction with the chiral (the amylose tris (3,5-dimethylphenyl carbamate) portion of the stationary phase. [As you and multidimensional both note above, to limit the ionized form(s) of the analytes-said another way, to act as ion-pairing agents.]
From FAQ #9, "For basic and acidic samples, it may be necessary to incorporate an additive in the mobile phase in order to allow the recognition and optimize the separation. Thus, basic samples may require a basic additive (DEA, butylamine, ethanolamine, ethylenediamine…) and acidic compounds the addition of an acid (TFA, acetic or formic acid…). The percentage needed is typically 0.1% and should normally not exceed 0.5%."
Best Wishes!