Studies On The Application Of Thermal Desorption And Pyrolysis-GC/MS Techniques On Pharmaceuticals And Food Safety Analysis

It is well known that many compounds in the areas of pharmaceuticals and food safety analysis are with high boiling point or strong polarity. In the analysis of these compounds, several pretreatments such as solvent extraction and derivatization were needed, which not only need a lot of treatment time but also reducing the reliability of the analyzing. Thus, it is eagerly requested to develop the practical and highly sensitive methods to analyze these compounds.Among various analytical methods, pyrolysis techniques such as pyrolysis-gas chromatography/mass spectrometry （Py-GC/MS）, evolved gas analysis-mass spectrometry （EGA-MS）, Heart-cut-EGA/MS and pyrolytic methylation/gas chromatography have been increasingly utilized as practical methods for the compounds with high boiling point or strong polarity.In this thesis, pyrolytic methylation/gas chromatography was applied to determination of spectinomycin in presence of tetramethylammonium hydroxide （（CH₃）₄NOH, TMAH）. With this method, spectinomycin was first converted into its basic degradation product, i. e. actinospectinoic acid. Then, actinospectinoic acid was converted into its corresponding methyl ether derivative in the injection port, well separated and determined without any pretreatment. Optimum conditions including the injector temperature at 300℃, and blending the sample with the TMAH （25%,v/v） methanol solution in a 1∶1 ratio. The achieved calibration curve exhibited good linearity with regression coefficient of 0.9992 at the concentration range from 0.1 to 20 g/L. High precision with the R.S.D. within 4% from the five continuous injections at 3 g/1 concentration and low limit of detection with 0.01 g/l were both achieved in this study. The method was applied to real-time controlling during the bioconversion of spectinomycin. Thus obtained results were compared to those obtained using microbiological assay.Secondly, EGA-MS and Heart-cut-EGA/MS techniques using a vertical microfurnace pyrolyzer was applied to discriminative analysis of food wrap films with their additives. The specific products of gas formed at thermal desorption and degration stages for the food wrap films were carried through a deactivated metal capillary column to MS detector with a helium gas. The qualitative results for all peaks on the obtained EGA curves were achieved by MS search and comparison. Furthermore, Heart-cut-EGA/MS was applied to separate components of the peaks in EGA curve. Thus, obtained results suggest that EGA-MS and Heart-cut-EGA/MS techniques are fast discriminative analysis methods for additive and polymeric materials of PE and PVC food wrap films, with convenience, accuracy, fast and without any pretreatment.Lastly, Py-GC/MS using the same pyrolyzer was applied to discriminative analysis of food wrap films with its additives. Pyrolysis of the food wrap films under 550℃yielded programs, which consist of the characteristic peaks of the constituents in given polymers with their additives. Simultaneously discrimination of food wrap films such as Polyethylene （PE）, Poly（vinyl chloride） （PVC） and vinyl chloride-vinylidene chloride copolymer （P（VC-VdC）） and analysis of their additives were achieved based on these characteristic peaks of the constituents in their programs with fairly good repeatability. The results showed that Py-GC/MS technique was a fast, convenience and effective method for discriminative analysis of food wrap films with its additives without any pretreatment.