Gas-Liquid Chromatographic Determination of Isosorbide Dinitrate in Tablets

Abstract

A gas-liquid chromatographic (GLC) method is described for determining isosorbide dinitrate (ISDN) in tablets. ISDN is extracted from tablet excipients by a 2-phase system composed of water-ethyl ether, and detected and quantitated with a flame ionization detector after separation from the internal standard (glyceryl tributyrate) on a 3% OV-210 column. Ten replicate assays on 2 different batches of tablets, each containing 5 mg ISDN, gave coefficients of variation of 1.16 and 1.48%, respectively. Comparison of results obtained for tablets containing 5, 10, and 40 mg ISDN, and for diluted isosorbide dinitrate raw material containing 25% ISDN, showed good correlation among the GLC, USP colorimetric, and USP polarographic procedures. Assay of synthetic mixtures containing ISDN, isosorbide-2-mononitrate, and isosorbide-5-mononitrate demonstrated that the GLC procedure is specific for ISDN, whereas the USP polarographic procedure is subject to interference from the mononitrates.

Review of UV spectroscopic, chromatographic, and electrophoretic methods for the cholinesterase reactivating antidote pralidoxime (2‐PAM)

“…As depicted in Figure , the proposed consecutive decomposition reaction of 2‐PAM (Figure , I ) is an initial OH ‐ ‐catalyzed dehydration to 2‐cyano‐N‐methyl‐pyridinium (Figure , VIII ), which is subsequently hydrolyzed to either N‐methyl‐2‐pyridone (Figure , XIII ) and CN ‐ or to 2‐carbamoyl‐N‐methyl‐pyridinium (Figure , IX ). This product is further hydrolyzed to 2‐carboxy‐N‐methyl‐pyridinium (Figure , X ), which is decarboxylated to N‐methyl‐pyridinium (Figure , XI ) . The limited stability under basic conditions restricts sample preparation and analysis thus favouring neutral or acidic pH.…”

“…However, under acidic conditions 2‐PAM also undergoes decomposition (Figure ). 2‐formyl‐N‐methyl‐pyridinium (Figure , V ) is formed by the release of hydroxylamine (NH 2 OH) followed by the production of 2‐hydroxymethyl‐N‐methyl‐pyridinium (Figure , VI ) . V can also be transformed into 2‐carboxy‐N‐methyl‐pyridinium (Figure , X ) in the presence of CN ‐ …”

“…Therefore, only two methods were found that applied RPC for 2‐PAM analysis (Table ) . In 1983, Prue et al .…”

“…In 1983, Prue et al . presented a quantitative method that was used for the determination of decomposition products of 2‐PAM in injectable pharmaceutical formulations . Isocratic separation of highly concentrated samples was performed on a Spherisorb‐ODS (C 18 ) column at ambient temperature using a solvent mixture of 5 mM phosphorus acid, 1 mM NEt 4 Cl and ACN (48:52 v/v) monitored at 270 nm (Table ).…”

“…Even though optimum absorptivity of 2‐PAM is well known to be at 293 nm under acidic and at 333–336 nm under alkaline conditions (Figure ) only a minority of methods applied these wavelengths (Tables , 2, and ). Instead, a broad variety of different wavelengths, for example, 262, 270, 280, 290, 294, and 300 nm were used. These settings might be due to (i) instrumental restrictions of older detectors in terms of light sources and monochromators (e.g.…”