A general static-headspace gas chromatographic method for determination of residual benzene in oral liquid pharmaceutical products

Sodium benzoate is used in oral liquid pharmaceutical products for its anti-microbial properties. The benzoate salts present in liquid pharmaceutical products can potentially generate residual levels of free benzene during manufacturing of the drug product and or during the shelf-life of the product under its storage conditions. To ensure the safety and quality of the pharmaceutical products (containing benzoate in the formulation), a selective and sensitive analytical method is required to monitor residual benzene in oral liquid pharmaceutical products. In this paper, we report the development and validation of a general static-headspace gas chromatographic (SH-GC) method to determine residual benzene in oral liquid pharmaceutical products. The liquid pharmaceutical drug product sample is dissolved in dirnethylsul-foxide (DMSO) in a GC headspace vial. A DB-624 capillary column (30111 x 0.32 mm I.D. and 1.8 mu m film thickness) was used under isothermal conditions with a flame ionization detection (FID). The benzene peak was well separated frog: all other volatile compounds that are present in the formulation of a number of liquid drug products. This method was successfully validated using a representative oral liquid pharmaceutical drug product. The limit of detection of the method for benzene is 0.5 ppm which met the 2 ppm limit of current ICH guideline for residual benzene in pharmaceutical products. (C) 2010 Elsevier B.V. All rights reserved.