Quality control of poly(methyl methacrylate) to medical purpose by multiple headspace extraction

The quality of polymers to be used for medical purposes is evaluated by the concentration of residual compounds in the polymeric matrix, especially by the amount of residual monomer. Residual components of the polymerization of monomer can cause allergies and biological complications (stomatitis, dermatitis, cheilitis, and irritability), also collateral effects for the patient which are evident from the first five years after implant placement and could remain for thirty years more. In dentures, for example, these components are dissolved by the saliva and are fixed to adjacent tissue causing allergic reactions, including burning. Multiple headspace extraction gas chromatography (MHS-GC) has been found to be an analytical technique particularly suitable for quantification of residual monomer in process samples with complex matrix, including solids. The major advantage of MHS-GC is that there is no need to pre-treat the sample prior to analysis. In this work, the methodology used to determine the residual monomer of Methyl Methacrylate (MMA) in a polymer of Poly(Methyl Methacrylate) (PMMA) is presented. The PMMA was produced in a controlled pilot plant scale laboratory, with rigorous experimental conditions to be used for medical purposes (artificial bone). The method includes the formulation of a calibration curve which was obtained by injecting different masses (0 - 30 mg) of a standard MMA solution in the Headspace sample vials and treated at ten extraction step in the HS-GC system. The results showed that through the present method it is possible to recover 98% of MMA from a solid matrix of PMMA.