Determination Of Haloacetic Acids And Farm Drugs Containing Nitrogen In Environmental Samples

With the developing economy, a wide range of so-called "new" unregulated contaminants have emerged as an environmental problem and became a hot topic for environmental analytical chemists. These compounds are commonly polar, non-volatile, thermally unstable so as to be unsuitable for gas chromatographic analysis. The dramatically advanced liquid chromatography and liquid chromatography-tandem mass spectrometry (LC-MS/MS) make it possible to set our sights on high polar compounds. In this paper, we applied ultra-performance liquid chromatography (UPLC) and LC-MS/MS in several important polar organic pollutants' analysis in different environmental medias, including haloacetic acids in drinking water and farm drugs containing nitrogen in soil.A method for the determination of nine haloacetic acids (HAAs) in drinking water by UPLC coupled with solid-phase extraction (SPE) was established in this paper. Optimization conditions of UPLC and SPE were determined by particular experiment design. We tested four buffer for good separation and peak shape. High responses of target compounds were acquired within 5 minutes when using triethylamine phosphate buffer as the mobile phase of UPLC. In addition, the different SPE sorbents and pH of water samples were tested and compared. Lichrolut EN cartridges showed the best recoveries. Water samples(100mL) were acidized to pH 0.5 with sulfuric acid, then extracted and cleaned up with Lichrolut EN SPE. We exploered the reason for disturbs from SPE, and eliminated it after washed the SPE column with Na2CO3 solution. Under the optimal experimental conditions, the limits of detection (S/N≥3) were generally between 0.25 and 0.70μg/L except for monochloroacetic acid (MCAA,10.85μg/L) and all the linear coefficient were between 0.9980 and 0.9999. The recoveries of HAAs spiked at three concentration levels were ranged from 60.0% to 106.4% except for MCAA. The relative standard deviation (RSD) of the method were between 2.0% and 5.7%(n=5). This method has been applied to analyze HAAs in the tap water sampled from water supply system in beijing, in which five of the nine HAAs were detected. The method was a convenient and quick one for the determination of trace level HAAs in drinking water.A method for the determination of carbamate pesticides and triazole fungicides in soil by LC-MS/MS was established. Optimization conditions of LC-MS/ MS were discussed. First, the influence on sensitivity by MS/MS and ESI instrument parameters was explored systematically. In order to acquire proper retain and good shapes of target compounds chromatograms, different liquid chromatography column and mobile phase were tested. Then, after comparison of different extracting and clean-up methods for soil samples, including traditional accelerated solvent extraction, ultrasonic extraction and solid phase extraction, QuEChERS method was found the most appropriate, which was an approach focus in the analysis of multiple pesticide residues of vegetables and fruits in recent years. In case of degradation of thermally labile compounds, we avoid any heating in sample preparation. The soil samples were extracted by shaking extracted with acetone and dichloromethane, and the extract was cleaned up by dispersive solid phase extraction, then analyzed with LC-ESI+ -MS/MS. Under the optimal experimental conditions, the method limits of detection (S/N≥3) were generally between 0.01 and 0.13μg/kg. The recoveries of target compounds spiked at two concentration levels were ranged from 64.7% to 105.8%. The relative standard deviation (RSD) of the method were between 1.98% and 16.83%(n=8). This sample preparation method we adopted was sensitive, simple, cheap and fast compared to the methods that were commonly used.