LAUSR

Graphical abstract Figure. No Caption available. HighlightsNovel approach for determination of DMSO as residual solvent in drug loaded gelatin.A variant of thermal desorption – gas chromatography was optimized and validated.Results confirmed by more complex conventional procedure using enzymatic digestion. Abstract Traditional headspace – gas chromatography (HS‐GC) methods for the determination of residual solvents (RS) start from a homogenous sample solution. Subsequently, it is challenging to determine RS using HS‐GC techniques from insoluble solid samples like gelatin which is practically impossible to dissolve or distribute uniformly in water and common organic solvents. In this study, a thermal desorber combined with capillary gas chromatography and flame ionization detection/mass spectrometry (TD‐GC‐FID/MS) was used for quantitative determination of residual dimethylsulfoxide (DMSO) in gelatin without sample pretreatment. A sample of gelatin was sandwiched between two quartz filter double layers in a polytetrafluoroethylene insert which was then placed in its entirety into a thermal desorption tube. Factors affecting the performance of TD‐GC including desorption time, desorption temperature, desorption flow and type of adsorbent were studied by applying a standard solution of DMSO in methanol on a blank gelatin bed. Validation results of the proposed method showed good linearity with an R2‐value higher than 0.999 for a wide concentration range and good sensitivity with a limit of detection and limit of quantification of 0.1 &mgr;g and 0.2 &mgr;g on tube, respectively. The proposed method shows recovery values close to 100%. In addition, a conventional HS‐GC method following enzymatic degradation of gelatin was developed to verify the proposed TD‐GC method. Both methods were applied for the determination of residual DMSO in gelatin that was loaded with an experimental drug. Results were comparable, but the enzyme assisted HS‐GC method was more time consuming and expensive.