| Heterocyclic pesticides are a kind of fastest-growing pesticides in recent years,and they have great market shares because of their high efficiency,low toxicity and low residue.However,extensive or inappropriate use of them can cause environmental pollution,and thus harm human health.Mercury is one of the most hazardous heavy metal elements to humans and the environment,which is widely distributed in nature.Although the concentration of mercury in environmental water sample is extremely low,the toxicity of mercury is very high.And the toxicity of mercury compounds not only depends on their concentration but also on their different species.Since the concentrations of heterocyclic pesticides and different species of mercury compounds in natural water are trace and ultratrace degree,which are below detection limits of many instruments,and the environmental water samples are generally complex,proper sample pretreatment techniques to enrich heterocyclic pesticides and different species of mercury compounds in water samples are needed.In this paper,magnetic solid phase extraction(MSPE)was used for preconcentration of six heterocyclic pesticides and different species of mercury compounds in water samples,then the analytes were determined by high-performance liquid chromatography(HPLC).1.Magnetic multi-walled carbon nanotubes(MWCNTs)were prepared and used as MSPE adsorbents for preconcentration of six heterocyclic pesticides in environmental water samples,followed by high-performance liquid chromatography-diode-array detector(HPLC-DAD)determination.The material was prepared by solvothermal method,and was characterized by XRD and SEM.Several variables affecting MSPE efficiency were systematically investigated,including amount of mag-MWCNTs,extraction time,type and volume of desorption solvent,desorption time,sample pH and salt concentration.Under optimized conditions,the enrichment factor of the method is 250,and excellent linearity was achieved in the range of 0.4–10.0 μg/L.Limits of detection was 0.01–0.03 μg/L.The intra-day and inter-day precision(relative standard deviation,n=6,%)at three spiked levels were 1.1–11.2% and 1.7–11.0% in terms of peak area,respectively.The method recoveries at three fortified concentration levels ranged from 72.2% to 107.5% for tap water,river water and reservoir water samples.The developed MWCNTs based MSPE coupled with HPLC method proved to be a convenient,rapid and excellent practical applicability to the sensitive determination of heterocyclic pesticides.2.Magnetic chitosan(MCS)nano-materials were prepared and used as magnetic solid-phase extraction adsorbents for preconcentration of MeHg and EtHg in environmental water samples,followed by high performance liquid chromatographyatomic fluorescence spectroscopy(HPLC-AFS)determination.Magnetic chitosan was synthesized then modified with aminothiourea(AT).The obtained AT-MCS was characterized by infrared spectroscopy,and the magnetism of the materials was tested.Several variables affecting MSPE efficiency were systematically investigated,including amount of adsorbent,sample pH and salt concentration,extraction time,volume of eluant,the elution time,and sample volume.Under optimized conditions,excellent linearity was achieved in the range of 0.08–1.6μg/L.Limits of detection were 0.023μg/L and 0.027μg/L for Me Hg and EtHg,respectively.The intra-day and inter-day precision(relative standard deviation,n=6,%)at three spiked levels were 2.37–7.16% and 2.79–9.70% in terms of peak area,respectively.The method recoveries at three fortified concentration levels ranged from 83.4% to 106.0% for tap water samples and reservoir water samples.The developed MSPE-HPLC-AFS method has some advantages,such as simple sample pretreatment procedure,convenient operation,no complicated equipment,high sensitivity and accuracy.The developed method is applicable to analyze trace level of MeHg and EtHg in environmental water samples. |
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