Determination of residual solvent in pharmaceutical preparations by static headspace GC

Determination of residual solvents and investigation of their effect on ampicillin trihydrate crystal structure

In the present work, the relationship between residual solvents concentration and ampicillin trihydrate crystals stability has been investigated. The amounts of residual solvents determined by GC, X-ray powder diffraction (XRPD) and Fourier transform infrared spectroscopy (FT-IR) were used for characterization of solid state. The obtained results have shown good relationship between concentration of methylene chloride (as a critical residue solvent) and degree of ampicillin trihydrate crystallinity. As with the increasing methylene chloride concentration in the sample the degree of crystallinity decreased after stability test. From this relationship, critical concentration of methylene chloride into the ampicillin trihydrate is obtained and the results can be used for improving the large-scale production of ampicillin trihydrate.

Analysis of organic volatile impurities as a forensic tool for the examination of bulk pharmaceuticals

This discussion offers an overview of some formally accepted methodology in the USA for the determination of organic volatile impurities in pharmaceuticals. Particular advantages of equilibrium headspace sampling with capillary gas chromatography for this task are outlined and some important considerations are expressed. Specific adaptations which we have made for forensic applications are described along with mention of select applications within the context of the detection of the counterfeiting of bulk pharmaceuticals. Finally, a brief description is provided of statistical techniques which can be used to effectively manipulate multivariate data sets for purposes of distinguishing between the manufacturers of a product based upon impurity profiles.

Assay of residual organic solvents in topiramate drug substance by capillary gas chromatography

The analysis of residual organic solvents (methanol, ethanol and toluene) in topiramate drug substance was investigated. Topiramate is a potent anticonvulsant drug under clinical evaluation. The drug is recrystallized from ethanol denatured by either methanol or toluene, and each residual solvent is controlled at 0.1% (w/w) level. A capillary gas chromatography (GC) method described in this manuscript utilizes a DB-WAX, 1 micron thick, 30 m x 0.53 mm i.d., column. Since topiramate is a thermally labile compound, the selection of the proper injector temperature is critical to the success of the analysis. The injector temperature was set at 120 degrees C to prevent degradation. The initial oven temperature was set at 55 degrees C for 8 min and programmed at a rate of 30 degrees C min-1 to a final temperature of 160 degrees C for 11 min. Helium was used as a carrier gas. The sample solvent selected was dimethylformamide pretreated with molecular sieves to remove trace amounts of alcohols that may interfere with the assay. The method was validated to be specific, linear, precise, sensitive, rugged and showed excellent recovery.