New approaches with two cyano columns to the separation of acetaminophen, phenylephrine, chlorpheniramine and related compounds

Investigation of endogenous blood plasma phospholipids, cholesterol and glycerides that contribute to matrix effects in bioanalysis by liquid chromatography/mass spectrometry

“…2). Chlorpheniramine (2-[p-chloro--[2-(dimethylamino)ethyl]benzyl]pyridine) is a strongly basic compound (pKa 9.1) with an aliphatic amine group (proton acceptor site) and a pyridine ring with a lone pair of electrons (active site for charge transfer) [16,17]. Chlorpheniramine has been shown to be susceptible to matrix effects that resulted in imprecise and inaccurate LC/MS/MS results [17].…”

Enantioselective determination of chlorpheniramine in various formulations by HPLC using carboxymethyl-β-cyclodextrin as a chiral additive

“…The separation factor (ratio of the stability constants of each enantiomer) was 1.60. There are two nitrogen atoms in the CP structure with pKa values of 3.77 at pyridine ring and 9.33 at alkyl chain (Olmo et al, 2005). As expected, the decreased pH value of mobile phase caused the decreased retention of the CP isomers on the lipophilic stationary phase through protonation (De Beer et al, 1996).…”

Development and validation of a reversed phase liquid chromatographic method for the determination of three Gliptins and Metformin in the presence of Metformin impurity (1-cyanoguanidine)

“…Unfortunately, simultaneous elution of the ternary mixtures at reasonable time could not be achieved. Recently, cyano columns have been used for the separation and quantitation of drugs [18][19][20][21]. Using a mobile phase of acidic pH value, C18 column was consequently replaced with a cyano column in order to separate mixture components.…”