Sayeeda Sultana, Balaji Nagarajan


Objective: We herein report the simultaneous trace level determination of benzene and 1,2-dichloroethane in several active pharmaceutical substances by GC-HS (gas chromatograph-head space) using a DB-624 column.


Methods: This GC-HS method was developed based on an oven-programmed approach using a nitrogen gas as the mobile phase. Our method is also compatible with the GC-MS (gas chromatograph-mass spectrometry) technique using helium as the mobile phase instead of nitrogen. The successful separation of benzene and 1,2-dichloroethane was established by confirmation of their corresponding specific molecular masses.


Results: The retention time of benzene and 1,2-dichloroethane were found to be 34.8 min and 35.6 min, respectively. The linearity was found in the range of concentration of 0.63-4.22 ppm and 1.49-9.96 ppm for benzene and 1,2-dichloroethane. The detection limit and quantification limit for benzene were 0.2 and 0.6 ppm, while those of 1,2-dichloroethane were 0.6 ppm and 1.5 ppm. These values were calculated using our developed method with respect to the test concentration of 500 mg/ml. The recovery of benzene and 1,2-dichloroethane were found to be 89–110% and 91–105%, respectively for the various pharmaceutical drug substances. The specificity of the method was studied using 20 solvents which includes benzene and 1,2-dichloroethane.


Conclusion: We expect that our method will be applicable for the simultaneous trace level determination of benzene and 1,2-dichloroethane during the control of manufacturing processes, and for use in rapid analysis for quality control in the pharmaceutical industry. Finally, this method was validated according to the International Conference on Harmonization (ICH) Validation Guidelines Q2 (R1).


GC, GC-MS DB-624, benzene, 1,2-dichloroethane, class-1 solvent, pharmaceutical substance


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