Analysis of Residual Solvents using GC/FID with Headspace and a ...

Measured SpecifiedPeak # Peak Identification Rt (min) S/N S/N1 1,1-Dichloroethane 4.06 108 > 32 1,1,1-Trichloroethane 9.90 186 > 53 Carbon Tetrachloride 10.53 15 > 34 Benzene 11.43 351 > 35 1,2-Dichloroethane 11.87 213 > 3Figure 1: GC/FID chromatogram for class 1 residual solventsResults and DiscussionThe acceptance criteria for USP 467,class 1 solvents, is that the signal-tonoiseratio for 1,1,1-Trichloroethane(peak 2) is greater than 5 and that thesignal-to-noise ratio obtained fromthe other compounds in the class isgreater than 3. The chromatogramand signal to noise measurementsobtained using the method describedpreviously are shown in Figure 1.The USP 467 method specificationfor class 2 solvents is that theresolution between acetonitrile anddichloromethane (peaks 2 and 3) isnot less than 1.0. The chromatogramsobtained for class 2 solvents (mixtureA and mixture B) are shown inFigures 2 and 3. The method criteriafor resolution between the criticalpair is met as these are fully resolved.All the other components are alsofully resolved, which demonstratesgood selectivity and efficiency of thechromatographic separation takingplace in the TRACE TR-V1 column.Poor response was observed for1,4-Dioxane, which was expected.Peak # Peak Identification Rt (min)1 Methanol 2.582 Acetonitrile 4.713 Dichloromethane 5.004 Trans-1,2-Dichloroethane 5.535 Cis-1,2-Dichloroethane 8.256 Tetrahydrofuran 9.167 Cyclohexane 9.948 Methylcyclohexane 15.979 1,4-Dioxane 18.3510 Toluene 23.3311 Chlorobenzene 27.1712 Ethyl Benzene 27.3913 m-Xylene/p-Xylene 27.6414 o-Xylene 28.42Figure 2: GC/FID chromatogram for class 2A residual solvents