Sample Pretreatment Study On Chromatographic Analysis Of Nitrosamine Disinfection By-products And Pyrazoles&Pyrroles Pesticides In Environmental Water Samples

Since matrix composition in the environment water is complicated, the contentsof the target compounds (trace organic pollutants) always exist at μg/L or ng/L level,and the sensitivity of the analytical instrument is limited, the development of simple,fast of the sample pretreatment technology with high enrichment factor and goodselection for trace contaminants in the environment water samples is the significantstep to improve the sensitivity and accuracy of the analytical method. Liquid liquidextraction (LLE) is a classical method of the samples pretreatment for thedetermination of environmental pollutants, but it requires large volume of toxicorganic solvents, therefore it has been replaced by some modern sample pretreatmenttechniques, such as solid phase extraction (SPE), solid phase microextraction (SPME)and dispersive liquid liquid microextraction (DLLME).In order to establish analytical methods of3nitrosamines and the4pyrazolesand pyrroles pesticides in the environmental water samples, SPE-DLLME combinedtechnology and multi-walled carbon nanotubes solid phase extraction were chosen asthe pretreatment methods in this study. The main contents of this paper are as follows:(1) SPE-DLLME combined with gas chromatography/mass spectrometry(GC-MS) was used to detect the nitrosamines disinfection by-products in drinkingwater samples. Some important extraction parameters affecting the performance of thetwo processes, such as the type and volume of the elution solvent, sample solutionflow rate, breakthrough volume, the type and volume of the extraction and dispersantsolvent, were thoroughly investigated and optimized. Under the optimal conditions,3nitrosamines, N-nitrosodi-n-propylamine (NDPA), N-nitrosodi-n-butylamine (NDBA)and N-nitrosodiphenylamine (NDPhA) in the drinking water were detected. The newmethod provided an ultra enrichment factors (EFs) for nitrosamines ranged from16076to31513. The method was applied for the selective extraction of nitrosaminesin the drinking water samples under the optimum SPE-DLLME and GC/MSconditions. The linear ranges for3nitrosamines were0.005μg/L-1μg/L. The limits ofdetections (LODs) of NDPA、NDBA and NDPhA were calculated to be0.50ng/L、0.23ng/L and0.17ng/L in water samples respectively, the method was successfully applied for the selective extraction and determination of nitrosamines in drinkingwater.(2) Determination method of4pyrazoles and pyrroles pesticides inenvironmental water samples by SPE-HPLC was developed using multi-walledcarbon nanotubes (MWCNTs) as SPE sorbent. The factors which will affect theextract efficiency were investigated, including the type of SPE sorbent, the type andvolume of eluent, sampling rate, and sample amount. Finally the optimal conditions ofSPE were determined. Under the optimal conditions, the linear ranges of flusilazole,fipronil, chlorfenapyr and fenpyroximate were0.05μg/L-20μg/L,0.05μg/L-20μg/L,0.05μg/L-10μg/L and0.05μg/L-10μg/L, respectively. The limits of detections (LOD)were0.008μg/L,0.014μg/L,0.013μg/L and0.019μg/L, respectively. The relativestandard deviations for five repeated determinations were between4.0%and9.9%.The results showed that MWCNTs can be an excellent SPE sorbent for pyrazoles andpyrroles pesticides. SPE-HPLC was successfully used for the determination ofpyrazoles and pyrroles pesticides in the real water samples, such as sea water, groundwater and tap water.