Stability of nitroglycerin injection determined by gas chromatography

The stability of nitroglycerin injection was studied over an eight-week period. Gas-liquid chromatographic assay and thin-layer chromatography were used to study the stability in relation to sorption by rubber and plastic (Viaflex), light and the effect of two diluents (5% dextrose in water and 0.9% sodium chloride for injection). More nitroglycerin was lost from vials with rubber closures, and the loss occurred at a faster rate when compared with nitroglycerin packaged in ampuls. There was no difference in the loss of nitroglycerin from injection packaged in ampuls when stored in the light or in the dark, or in the loss of nitroglycerin from two diluents, 5% dextrose in water and 0.9% sodium chloride for injection, packaged in glass bottles. A 70.4% greater loss of nitroglycerin occurred from Viaflex bags than from glass bottles. Loss of nitroglycerin in this study may have been characterized by reversible first-order kinetics.