Development of a rapid GC-FID method to simultaneously determine triethylamine, diisopropylamine, and 1,1,3,3-tetramethylguanidine residues in an active pharmaceutical ingredient.

A rapid GC-FID method was developed to simultaneously determine residual levels of triethylamine (TEA), 1,1,3,3-tetramethylguanidine (TMG), and diisopropylamine (DIPA) in the synthetic route of an active pharmaceutical ingredient (API). Due to the severe absorption of amines on GC stationary phases, GC columns with various stationary phases were evaluated for optimal peak shape and reproducibility. The final conditions used the Agilent CP-Volamine column to resolve the three amines in 12 min.

Separation of therapeutic peptides with cyclofructan and glycopeptide based columns in hydrophilic interaction liquid chromatography.

Three cyclofructan-based, two glycopeptide-based, and one zwitterionic column used in the HILIC mode were assessed within a graphical framework based on different functional characteristics contributing to selectivity. The characteristics of these six HILIC columns are put in the perspective of 33 columns evaluated previously. The isopropyl carbamate modified cyclofructan 6 (CF6) stationary phase, Larihc P, showed reduced component contributions for hydrophilicity and hydrogen bonding relative to the native cyclofructan 6 column (Frulic N).

Thermodynamic studies of a zwitterionic stationary phase in hydrophilic interaction liquid chromatography.

A zwitterionic 3-P,P-diphenylphosphonium-propylsulfate stationary phase called HZI was synthesized for hydrophilic interaction liquid chromatography (HILIC). A set of 15 solutes including apolar aromatic compounds, positively charged β-blockers, polar nucleic acid bases and negatively charged compounds was used to prepare van't Hoff plots between 10 and 70°C with HILIC mobile phases containing between 10 and 20% v/v 20mM or 50mM ammonium acetate buffer (pH 4.1) in acetonitrile.

Development and evaluation of new zwitterionic hydrophilic interaction liquid chromatography stationary phases based on 3-P,P-diphenylphosphonium-propylsulfonate.

New zwitterionic stationary phases were synthesized by covalently bonding 3-P,P-diphenylphosphonium-propylsulfonate to silica gel. The resulting materials possess both a negatively charged sulfonate group and a positively charged quaternary phosphonium group, which means that there is no net charge over a wide pH range. The retention mechanism and chromatographic behavior of polar solutes under HILIC conditions were studied on these zwitterionic phases.

Cyclofructan 6 based stationary phases for hydrophilic interaction liquid chromatography.

New stationary phases for hydrophilic interaction liquid chromatography (HILIC) were synthesized by covalently attaching native cyclofructan 6 (CF6) to silica gel. The chromatographic characteristics of the new stationary phases were evaluated and compared to three different types of commercial HILIC columns. The CF6 columns produced considerably different retention and selectivity patterns for various classes of polar analytes, including nucleic acid compounds, xanthines, β-blockers, salicylic acid and its derivatives, and maltooligosaccharides.

Evaluation of aromatic-derivatized cyclofructans 6 and 7 as HPLC chiral selectors.

The two best aromatic-functionalized cyclofructan chiral stationary phases, R-naphthylethyl-carbamate cyclofructan 6 (RN-CF6) and dimethylphenyl-carbamate cyclofructan 7 (DMP-CF7), were synthesized and evaluated by injecting various classes of chiral analytes. They provided enantioselectivity toward a broad range of compounds, including chiral acids, amines, metal complexes, and neutral compounds. It is interesting that they exhibited complementary selectivities and the combination of two columns provided enantiomeric separations for 43% of the test analytes.