RESUMEN
A polyimide coated stir bar for sorptive extraction (SBSE) was prepared by immersion precipitation method, and evaluated by using 5 phenols and chlorinated phenols as model samples. The extraction efficiency of the prepared stir bar was the highest compared with commercial extraction phases of SBSE. Experimental parameters including stir speed, ionic strength, extraction temperature, extraction time, desorption temperature and time were optimized. Under the optimal conditions such as 100 mL of sample, 30 g of NaCl, extraction time of 30 min, stirring speed of 800 r/ min and at 25℃, the target compounds were recovered by thermal desorption at 300℃ for 4 min, more than two orders of magnitude of linearity was obtained (R≥0. 9995), LOQs (S/ N=10) were 0. 028-0. 123 μg/ L, and RSDs were in the range of 1. 6% -9. 7% . The polyimide SBSE coupled with gas chromatography-mass spectrometry was applied to the extraction/ enrichment and analysis of phenols in real samples, including tap water, sea water, and waste water. It was found that the polyimide SBSE showed high selectivity towards polar compounds and high thermostability up to 350℃.
RESUMEN
Teeth that have short clinical crown, which are not alone enough to support the definitive restoration can be best treated using the post and core system. The advantages of fiber post over conventional metallic post materials have led to its wide acceptance. In addition to that the combination of aesthetic and mechanical benefits of fiber post has provided it with a rise in the field of dentistry. Also the results obtained from some clinical trials have encouraged the clinicians to use the fiber posts confidently. Fiber posts are manufactured from pre-stretched fibers impregnated within a resin matrix. The fibers could that be of carbon, glass/silica, and quartz, whereas Epoxy and bis-GMA are the most widely used resin bases. But recently studies are also found to be going on for polyimide as possible material for the fiber post resin base as a substitute for the conventional materials.