Preparation and Application of Polyimide Coated Stir Bar for Extraction of Phenols in Environmental Water Samples

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 highest extraction efficiency was achieved among all commercial extraction phases of SBSE reported. Experimental parameters including stirring speed, ionic strength, extraction temperature, extraction time, desorption temperature and time were optimized. Under the optimal conditions such as 100 mL of sample, 30% NaCl, extraction time of 30 min, stirring speed of 800 rpm and extraction temperature of 25 degrees C, the target compounds were recovered by thermal desorption at 300 degrees C for 4 min. More than two orders of magnitude of linearity were obtained (R >= 0.9995). LOQs (S/N = 10) were 0.028-0.123 mu g L-1, 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 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 degrees C