Metsulfuron-methyl Molecularly Imprinted Stir Bar Sorptive Extraction Coupled with High Performance Liquid Chromatography for Trace Sulfonylurea Herbicides Analysis in Complex Samples

Metsulfuron-methyl molecularly imprinted polymer（MIP）-coated stir bar was prepared for sorptive extraction of sulfonylurea herbicides in complex samples.The MIP-coating was about 21.3 μm thickness with the relative standard deviation（RSD） of 4.4%（n=10）.It was homogeneous and porous with good thermal stability and chemical stability.The extraction capability of the MIP-coating was 2.8 times over that of the non-imprinted polymer（NIP）-coating in hexane.The MIP-coating exhibited selective adsorption ability to the template and its analogues.The extraction conditions,including extraction solvent,desorption solvent,extraction time,desorption time and stirring speed,were optimized.A method for the determination of six sulfonylurea herbicides by MIP-coated stir bar sorptive extraction coupled with high performance liquid chromatography（HPLC） was developed.The linear range was 10―200 μg/L and the detection limits were within a range of 2.0―3.3 μg/L.It was also applied to the analysis of sulfonylurea herbicides in spiked river water,soil and rice samples.

An Electropolymerized Pyrrole-based Coating for Stir Bar Sorptive Extraction of Btex from Water Followed by Gas Chromatography-Mass Spectrometry

A stir bar sorptive extraction （SBSE） technique was developed by the use of polypyrrole （PPy） sorbent, electropolymerized on the surface of a rod, as a possible alternative to solid-phase microextraction （SPME）. Liquid desorption was subsequently employed to transfer the extracted analytes into the injection port of a gas chromatogra- phy-mass spectrometry （GC-MS）. The PPy sorbent including polypyrrole-dodecyl sulfate （PPy-DS） was deposited on the surface of a stainless steel rod from the corresponding aqueous electrolyte by applying a constant deposition potential. The developed method was applied to the trace level extraction of BTEX （benzene, toluene, ethylbenzene, o,p-xylene） from aqueous sample. Optimization of influential experimental conditions including the voltage of power supply, the time of PPy electrodeposition, the extraction temperature, the ionic strength and the extraction time were also investigated. The detection limits of the method under optimized conditions were in the range of 0.01-0.1 ng.mL^-1. The relative standard deviations （RSD） at a concentration level of 1 ng.mL^-1 were obtained between 8% and 13% （n=6）. The calibration curves of BTEX showed linearity in the range of 0.03 to 600 ngomL 1. The proposed method was successfully applied to the extraction of some selected BTEX from river water samples and the relative recoveries were higher than 90% for all the analytes.

PDMS Rod-SBSE System Coupled with Gas Chromatography for Determination of PAHs in Aqueous Samples

A method for the analysis of trace polycyclic aromatic hydrocarbons（PAHs） in aqueous samples has been established by polydimethylsiloxane（PDMS） rod aided stir bar sorptive extraction（SBSE）. The homemade PDMS rod has a size of 30 mm×3 mm o.d. with a volume of ca. 200 μL, stable in thermal desorption process. The enriched PAHs by the PDMS rod were released in a homemade thermal desorption system coupled with gas chromatography. Experimental parameters for extraction of six PAHs were optimized including extraction time, pH, ionic strength and temperature of solution. The procedure has good recoveries of 80.0%―100.3% and very low limits of detection of 4.0―33 ng/L. PAHs in rain and river water were analyzed by this method.