| A new fast and efficient method to detect environmental pollutants-dispersive solidphase extraction was established. It could enrich and concentrated microcystins, odorsubstances in the water environment accurately and quickly. Microcystins, odor substancesare determinated qualitatively and quantitatively. Dispersive solid-phase extractionconditions were optimized, under the best experimental conditions of actual water sampleswere analyzed.The main work of this paper was as follow:1.Research objects were briefly described: microcystins, odor substances, theirsources, hazards and commonly analytical methods of microcystins and odor substances.Several common sample pretreatment methods were introduced, and dispersive solid-phaseextraction is presented on the basis of phase extraction.2. Instrument parameters were optimized of high performance liquid chromatography-time of flight mass spectrometry (LC-Q-TOF-MS)through1μg/mL mixed standardsolution and got the best conditions: the chromatographic column was AgilentSB-C18column with a mobile phase of0.1%formic acid aqueous solution (A)-methanol solution(B), a flow rate of0.3mL/min. With double-needle electrospray ion source (Dual AJS ESI),they were tested by positive ion scanning mode. Through the optimization of dispersivesolid phase extraction conditions, the optimum extraction conditions were got: regulatedwater pH value to2.0,0.500g HC-C18as dispersant, eluted with8ml dichloromethane,vibrated for30min, eluent of10%methanol aqueous solution. Under the optimumconditions, the lowest detection limit (LOD) of three kinds of microcystins was between2.1~5.7ng/L. In the concentration range of0.02-10.00μg/L, the peak area was linear withthe sample concentration relationship. Using the above method, Stone Lake samples weremeasured in August, and found that the microcystin was presented in the surface water,including MC-RR content of0.42μg/L and MC-YR, MC-LR was not detected. About1.00μg/L plus scalar of actual samples, the standard recovery rate was between85.67%to93.00%and the precision of between2.67%to7.29%. And Lake samples were measuredfor December and microcystin contamination was not found. Under the standard additionlevel of0.50μg/L, the actual water samples of standard addition was between78.00%to86.00%, and the precision (RSD) between1.36%to5.83%.3.Followed with further validation, dispersive solid-phase extraction technology was applied to determination of geosmin,2-methyl isobutyl borneol(2-MIB), β-cyclocitral,β-ionone,2,4,6-trichloro-anisole(TCA),2-isopropyl-3-methoxy pyrazine (IPMP),2-isobutyl-3-methoxy-pyrazin(IBMP) in surface water. The optimum experimentalconditions to determination odor material in water with dispersive solid-phase extractionwere determined:0.300g HC-C18as dispersant, regulated water pH value to7.0,vibrated for15min, eluted with6ml dichloromethane. Under the optimum experimentconditions, the determination results of seven kinds of odor material showed goodreproducibility and high precision. Within the scope of0.05to10.0mu g/L, it showedgood linear relationship between peak area and concentration, the correlation coefficientbetween0.9946to0.9997, the lowest detection limit between1to5ng/L. In water fromStone Lake at spiked level of1.00μg/L, relative standard deviation (RSD) is7.1%-13.3%,the standard addition recovery was81.6%-81.6%. This method can be applied tosimultaneous determination of seven kinds of odor material in the surface water.4. The experimental section was further summarized, the method of dispersive solidphase extraction and solid phase extraction were compared. The problems oftime-consuming and easy to plug in solid phase extraction method were overcame bydispersive solid phase extraction method. Thereby, dispersive solid-phase extraction couldexpand the range of applications in the further study. |
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