| More and more studies show that some micro-organic substances such asendocrine disruptors, disinfection byproducts and microcystins in drinking water havecarcinogenic, teratogenic and mutagenic effect for human. The concentration of thesubstance usually stays in drinking water at μg/L or ng/L grade, thus, developingsensitively and fast detection methods have becaming more and more important inwater quality management. There are two parts in this thesis, in part1, simple and rapidmethods are developed using ultra performance liquid chromatography-electrosprayionization tandem mass spectrometry (UPLC-ESI-MS/MS) for determining phthalates(PAEs), haloacetic acids (HAAs) and microcystin-LR (MC-LR) in drinking water.The World Health Organization (WHO) recommends a guideline value of MC-LR1μg/L; however, since the guideline value is based on the acute toxicity, it does not takeinto account the effects of possible long-term exposure to MC-LR at a lowconcentration. A new study indicated that there were kinds of chronic health effectswhen human intake the WHO value at long time. In order to safeguide the drinkingwater, in part2of this study investigated the reaction kinetic characteristics of MC-LRat low concentrations, and discussed the final concentration of MC-LR in drinkingwater treatment processes.The main conclusions of this study are as follows.（1）With a large number and diverse of commercial plastic products in use, PAEshave found their way ubiquitously into environmental compartments. In the analysis ofphthalates, specifically diethyl phthalate (DEP), dibutyl phthalate (DBP), butylbenzylphthalate (BBP), and diethylhexyl phthalate (DEHP) using UPLC-ESI-MS/MS,‘ghostpeaks’ appeared when a gradient liquid chromatography elution mode was employed. A systematic diagnostic analytical protocol was designed to show that the source of thepersistent ‘ghost peaks’, which jeopardized a quantitative analysis of these endocrinedisruptors was the mobile phase. A trace amount of DEHP in the mobile phase, eitherfrom ultrapure water or organic solvent, was responsible for the observed phenomenon.In contrast to gradient elution, isocratic chromatographic elution mode (ICEM) wasfound to be free of the problem at the expense of less effective separation of DBP andBBP. Thus, a detection method for analyzing the phthalates is proposed based on ICEMand the multiple reaction monitoring (MRM) modes with multi-channel detection in theUPLC-MS/MS. In the method development, tap water matrix effects were examinedand a solution for detection intensity suppression in the analysis of tap water sampleswas proposed. An addition of methanol into tap water samples could basically relievethe signal detection suppression by the real water matrix. This provides a detectionmethod of these trace environmental pollutants with a linear range between0.5to50μg/L and detection limits (LODs)(0.32-0.54μg/L) without need of samplepre-concentration. It is a simple, fast and sensitive method for determining PAEs indrinking water.（2）After trihalomethanes (THMs), haloacetic acids (HAAs) are the second mostprevalent group of disinfection byproducts in chlorinated water. There are manydisadvantages in methods for detecting haloacetic acids (HAAs), for example, complexpreparation, large amounts of toxic organic reagents, high detection limits and nineHAAs can not be separated completely. In this paper, a simple and rapid detectionmethod for nine HAAs in water has been developed using UPLC-ESI-MS/MS inmultiple reactions monitoring (MRM) mode. A separation mechanism of the ionicanalytes using a reversed phase liquid chromatographic column (HSS T3) possessing ahydrophilic affinity has been proposed and discussed. Addition of a small amount offormic acid (FA) as a modifier for the methanol-water eluent was found to be critical forseparation of the analytes with smaller molecular size (i.e. the mono and di-haloaceticacids). Without the need of sample preconcentration, very low limits of detection (LODs)for the nine HAAs were achieved (0.06-0.16μg/L). The linear calibration rangeextended from0.5up to100μg/L (R2=0.9993-0.9997, n=6). The water matrix effect hasbeen examined, and seems to be related to the ions in real water samples. Interestingly, an adjustment of the pH of the tap water samples to an acidic value of3.0or belowbasically eliminated the matrix effect. The method has been tested using tap watersamples sourced from both surface water (total dissolved solid (TDS):145±3mg/L) andgroundwater (TDS:362±1mg/L) with high precision and recovery.（3）MC-LR has been identified as the most common and most toxic ofmicrocystins in the natural water, and analysis of MC-LR in drinking water is veryimportant. A simple detection method using UPLC–ESI–MS–MS coupled with thesample dilution method for determining trace microcystin-LR (MC-LR) in drinkingwater is presented. The limit of detection (LOD) was0.04μg/L and the limit ofquantitation (LOQ) was0.1μg/L. Water matrix effects of ionic strength, dissolvedorganic carbon (DOC) and pH were examined. The results indicate that signal detectionintensity for MC-LR was significantly suppressed as the ionic strength increased fromultrapure water condition, whereas it increased slightly with solution pH and DOC atlow concentrations. However, addition of methanol (MeOH) into the sample was able tocounter the signal suppression effects. In this study, dilution of the tap water sample byadding4%MeOH (v/v) was observed to be adequate to compensate for the signalsuppression. The recoveries of the samples fortified with MC-LR (0.2,1, and10μg/L)for three different tap water samples ranged from84.4%to112.9%.（4）Chlorine and permanganate are common used disinfectant in drinking watertreatment, therefore, study the degradation characterism of trace organic substances bychlorine and permanganate are very important. In response to the increasing concerns inthe literature about its human toxicity in drinking water at very low concentration levels,this study investigated the destruction of MC-LR down to concentrations of ng/L byboth chlorine and permanganate. The results showed that, similar to the previous studiesof MC-LR oxidation in the high concentration range (1g/L) the decomposition in thelow concentration range (1g/L-2ng/L) exhibits the features of pseudo-first-orderreaction with respect to each of the two oxidants in pure water solution conditions.However, when reaction proceeded down to a very low concentration (10ng/L) adifferent or a much smaller rate constant dictates the kinetics. In addition, in thepresence of humic acids (HA) in solution the reaction rates and the final concentrationremoval limit were affected presumably due to competition from reactions between the oxidant and HA. The behavior and the extent of such detrimental influence variedbetween the two oxidants. This creates some profound effects of the governance of anoxidant exposure CT over MC-LR degradation between the two oxidants, likely relatedto different reaction mechanisms of the two oxidants with MC-LR under the solutionconditions. This study indicates that chlorine and permanganate may be still effectivefor MC-LR decomposition down to a concentration of10ng/L or below; however theinfluence of solution chemistry (particularly pH for chlorine, and natural organic matterfor permanganate) must be carefully examined before a feasible CT is determined forthe control of this toxin in a water treatment system. |
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