|Molecular Weight||114.023 g/mol|
Organic and inorganic acids and ions can be separated on a Primesep B4 column based on their ionic properties. Method can be used for quantitation of residual acids in various products and sample matrices. Trifluoracetic, hydrochloric, methanesulfonic, and nitric acids are separated using ACN-water-ammonium formate. Ions can be detected by ELSD, CAD or LC/MS.
Dual functionality of Obelisc N column allows to retain and provide efficient peaks of strong carboxylic acids such as TFA. Simple UV quantitation and identification method became possible due to the unique properties of this stationary phase. In case of an RP separation poor retention and peak symmetry was obtained at a very low concentration of ACN. Sulfuric acid was used to suppress ionization of TFA to increase the hydrophobicity. In case of a typical HILIC column the phosphoric acid was used to increase ionization to make TFA more polar to enhance polar retention. The types of columns that do not have the mixed mode nature of Obelisc N can't provide significant retention and efficiency.
Trifluoroacetic acid (TFA) is a strong carboxylic acid, with pKa of 0.3. TFA is widely used in chemistry as reagent and as counter-ion for basic drugs and other compounds. TFA is very polar in nature, and has low UV activity. It is often required to quantitate trifluoracetic acid in various formulations. HPLC method for determination of trifluoroacetic acid on Obelisc N column provides a viable alternative for quantitation of TFA. TFA is retained by ion-exchange mechanism on mixed-mode HILIC column. Relative comparison shows high loadability of the method. Obelisc N columns show much better peak shape and retention than traditional HPLC columns (Atlantis T3 from Waters). Perfect peak symmetry is achieved by adjusting amount of acetonitrile, buffer pH and buffer concentration. TFA is monitored by low UV (200 nm). Alternatively trifluoroacetic acid can be analyzed by ESLD with ammonium formate in the mobile phase. TFA forms non-volatile salt with ammonia, thus giving ability to quantitate it.
Ionic liquid is an ionic compound which is liquid at room (or close to room) temperature. Most of the ionic liquids are in a dynamic equilibrium where at any time more than 99.99% of the liquid is made up of ionic, rather than molecular, species. Room-temperature ionic liquids consist of bulky cation (for example, substituted imidazolium) compounds. A wide range of anions is used as counter ions in ionic liquids: organic and inorganic anions such as chloride, iodide, tetrafluoroborate, hexafluorophosphate, bistriflimide, triflate, tosylate. Ionic liquids are widely used as solvents in organic reactions. When products are isolated from ionic liquids, they need to be analyzed for residual ionic liquid content.
Because both constituents of the ionic liquid are very different in terms of charge and hydrophobic properties, it is impossible to analyze entire ionic liquids by traditional chromatography. An effective and universal method for analysis of ionic liquids is developed on an Obelisc R HPLC column. Components on the ionic liquids are retained based on ionic and hydrophobic interactions. Obelisc R column has both positively and negatively charged ionic groups, making it possible to retain and separate cations and anions of ionic liquids on one column. Method can be used for quantitative of various ionic liquids containing organic and inorganic ions. Retention time of basic component can be effectively adjusted by pH, stronger anionic and hydrophobic counter-ions might require higher buffer concentration. Composition can be monitored by combination of UV and ELSD or by LC/MS.
|Column||Obelisc N, 4.6x150 mm, 5 µm, 100A|
|Mobile Phase||MeCN - 60%|
|Buffer||H2SO4 - 0.05%|
|Flow Rate||1.0 ml/min|
|Detection||UV, 210 nm|
|Class of Compounds||Acid, Hydrophilic, Ionizable|
|Analyzing Compounds||Trifluoroacetic acid (TFA), Acetic acid (AcOH)|