Study On Monitoring Method For Semivolatile Organic Compounds In Groundwater By GC-MS

With the rapid development of the society in recent years, a large amount of three wastes(waste gas, waste water and residues) being discharged are polluting the environment, especiallygroundwater more and more severe. The Environmental Protection Agency (EPA) hasdistinguished 129 toxicants (114 organics included) from 70,000 compounds, and these toxicantsshould be first controlled. In most cases, concentrations of organic pollutants are too low to beobserved so that the routine analysis on water quality does not work. Therefore, organic pollutesin groundwater bring about more complexity, concealment and dangerousness.As far as the current grim polluted groundwater is concerned, it is the arduous task for ourenvironmentalists to test those poisonous compounds already confirmed dangerous toenvironment, emphasize monitoring work, considering that to monitor groundwater is extremelyessential in maintenance and management of groundwater resources, and all of national andregional long-term programming, policy-making are almost based on corresponding data viamonitor.This paper takes agricultural chemicals bearing organic chlorine and polycyclic aromatichydrocarbons as examples, applies compare the traditional liquid-liquid extraction with the C18solid-phase membrane extraction, and establishes high-precision GC-MS qualitative andquantitative measure approach, by which some practical water samples are scanned anddetermined with mass spectrum, and the following conclusion can be safely drawn:1. Pure water is taken as blank reagent (control) based on the result of GC-MS test;2. According to the spiked recovery experiment of different volume samples, the recoveryrate from the liquid-liquid extraction is lower than 70% with an average 65% or so, but therecovery rate from the C18 solid-phase extraction varies from 70% to 120%,the latter meets therequirement of the US EPA.3. The relative standard deviation in the liquid-liquid extraction experiment is 25% or so, andthat in the C18 solid-phase extraction is approximately 15%, which both meet the requirement ofthe US EPA.4. The conclusion drawn from the spiked recovery experiment and the precision experimentindicated that the C18 solid-phase membrane extraction is characterized as solvent saving, shortduration and excellent reclaiming effect. Therefore, the method was adopted to deal with thewater samples at pretreatment stage.5. The water samples from the Northern Paradise Rubbish Disposal Site are tested and resultthat the water contained a variety of the semi-volatile organism. The experiment indicates that thegroundwater in this area is suffered from the pollution of benzene and polycyclic aromatichydrocarbons, to which much importance and attention should be attached.6. The current concentration of the agricultural chemicals bearing organic chlorine in thegroundwater are tested less than 31.30ng/L in Beijing, and that of polycyclic aromatichydrocarbons is less than 62.70ng/L.Based on USA EPA and National Standard, and combining correlated information, thisproject researches on the liquid-liquid extraction, the C18 solid-phase membrane extraction andGC-MS determining organic compounds in groundwater. Likewise, the experimental approach issuitable to analyze and determine organic compounds in surface water.