土壤和沉积物中草甘膦的检测方法

发布时间：2018-01-01 17:00

本文关键词：土壤和沉积物中草甘膦的检测方法　出处：《南京理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：草甘膦(Gly)自1974年推向市场以来,因为其具有较强的内吸传导性和广谱的灭杀效果,已成为使用最为普遍、销售量最大的除草剂。由于草甘膦的使用量越来越大,施药范围越来越广,且其在土壤中具有中等的持留性(t1/2在1-174d),草甘膦在土壤环境中的污染也越发受到关注。我国的《土壤环境质量标准》(修订)(GB15618-2008)的征求意见稿中增加草甘膦为有机污染物之一。草甘膦的化学性质使得对它的分析测定困难,草甘膦的极性和水溶性不利于对其进行提取,而且草甘膦缺少发色基团和荧光基团,在利用色谱法进行检测前必须先进行衍生。尤其在土壤环境中,草甘膦极易被土壤颗粒吸附,并与土壤中有机质、腐殖酸、金属氧化物及重金属离子等反应,所以对土壤中草甘膦的痕量检测愈加困难。目前,我国还没有土壤及沉积物中草甘膦的标准检测方法,而之前报道过的分析方法,如采用气相色谱串联质谱或液相色谱串联质谱法进行检测,由于操作复杂,造价昂贵等原因,无法大范围推广。为了更好地监测和分析草甘膦在土壤和沉积物中的污染状况,迫切需要建立一套经济实惠,实施方便且准确可靠的土壤及沉积物中草甘膦的标准检测技术。本文建立了土壤和沉积物中草甘膦测定的标准检测方法,并探究了土壤的不同理化性质对草甘膦检测的影响,并按照《环境监测分析方法标准制修订技术导则》(HJ 168)和《国家环境污染物监测方法标准制修订工作暂行要求》(环科函[2009]10号)的要求,对该标准方法进行了六家实验室验证。主要研究内容和结果如下:(1)土壤及沉积物中草甘膦分析方法的建立:土壤样品用0.03 mol/L磷酸钠和0.01 mol/L的柠檬酸三钠混合溶液提取,超声提取后,用盐酸(HC1)调节溶液pH至9,经正己烷萃取净化,萃取液与9-芴氯甲酸甲酯(FMOC-C1)进行衍生化反应,采用液相色谱-荧光检测器,以乙腈/0.2%磷酸水溶液作为流动相,对样品进行检测。对样品前处理方法进行优化,通过磷酸盐与草甘膦在土壤中竞争吸附位点,降低草甘膦的吸附量,并通过添加金属离子络合剂解除草甘膦与土壤中金属离子的络合,解决了土壤中草甘膦提取困难的难题。该分析方法操作简单,灵敏度高,重现性好。在0.005～0.5 mg/L浓度范围内,标准工作曲线的线性相关系数R20.999,土壤样品平均回收率为75%-100%,相对标准偏差均15%。方法检出限为0.01 mg/kg,测定下限为0.04mg/kg,添加回收率及检出限均能满足农土壤环境质量标准要求(0.5mg/kg)。(2)通过比较土壤腐殖酸含量,土壤pH值和七种重金属离子对草甘膦回收率的影响,探究土壤理化性质对草甘膦检测的影响。结果表明:土壤中有机质含量越高,对草甘膦的吸附越强,回收率越低;土壤pH值对草甘膦的回收率有重大影响。在酸性土壤中,草甘膦以分子形态存在,而在碱性条件下,大多是以阴离子的形态存在,与带有负电荷的土壤颗粒相排斥,减少了草甘膦的吸附量;土壤中的重金属离子(Cu~(2+),Fe~(2+),Fe3+,Zn~(2+),Ni~(2+))可以和草甘膦形成稳定的络合物,使回收率降低。而重金属离子Co~(2+)和Mn~(2+)对草甘膦没有影响;建立的土壤和沉积物中草甘膦的检测方法能满足各种类型的土壤和沉积物。其中磷酸钠和柠檬酸三钠提取液具有缓冲溶液的效果,可以适应各种pH环境的土壤,而且柠檬酸三钠可以去除土壤中大部分重金属离子的干扰。(3)按照《环境监测分析方法标准制修订技术导则》(HJ 168)和《国家环境污染物监测方法标准制修订工作暂行要求》(环科函[2009]10号)的要求,组织了 6家有资质的实验室对该标准方法进行验证。6家实验室验证结果表明,方法检出限为0.011 mg/kg,测定下限为0.043 mg/kg。远低于我国环境质量标准限值(0.5 mg/kg),所以本方法检出限满足现在及以后环保标准的要求。方法具有较好的重复性和再现性,湖南红壤的重复性限为0.016mg/kg-0.134 mg/kg,再现性为0.034mg/kg-0.299 mg/kg,基质加标回收率最终值为 99.21%±11.75%-101.15%±9.60%;水稻土的重复性限为 0.015mg/kg-0.139mg/kg,再现性为0.027mg/kg-0.214mg/kg,基质加标回收率最终值为83.53%±5.96%-88.79%±4.11%;东北黑土的重复性限为 0.016mg/kg-0.147mg/kg,再现性为 0.020mg/kg-0.172mg/kg,基质加标回收率最终值为 79.96%±10.09%-83.66%±3.11%;前湖沉积物的重复性限为0.017 mg/kg-0.140 mg/kg,再现性为0.024 mg/kg-0.178 mg/kg,基质加标回收率最终值为75.31%±9.70%-80.62%±12.92%;秦淮河沉积物的重复性限为0.018 mg/kg-0.182 mg/kg,再现性为0.022 mg/kg-0.208 mg/kg,基质加标回收率最终值为79.26%±10.07%82.03%±10.14%。结果表明,该标准方法的各项特性指标能达到预期要求。
[Abstract]:Glyphosate (Gly) since 1974 to the market, because of its strong absorption within the conduction and broad-spectrum killing effect, has become the most widely used, the largest sales due to the use of glyphosate herbicide. More and more big, more and more wide range of application, and in the soil with moderate retention (t1/2 in 1-174d), pollution of glyphosate in the soil environment is more and more attention. "Soil environmental quality standard in China" (Amendment) (GB15618-2008) draft increased glyphosate as organic pollutants. The chemical properties of glyphosate and makes analysis on it is difficult to determine the polarity and water solubility of glyphosate is not conducive to the extraction, and the lack of glyphosate chromophore and fluorophore, are must be derived before detection in the use of chromatography. Especially in the soil environment, glyphosate is easily adsorbed by soil, and And the organic matter in the soil, humic acid, metal oxides and heavy metal ions and other reactions, so more difficult to trace detection of glyphosate in soil. At present, no method for detection of glyphosate in soil and sediment in China, and the analysis methods reported before, such as the use of gas chromatography or liquid chromatography tandem mass spectrometry mass spectrometry detection, because of complex operation, high cost and other reasons, can not be extended. In order to pollution in soil and sediment in better monitoring and analysis of glyphosate, the urgent need to establish a set of economic benefits, the implementation of glyphosate in soil and sediment is convenient and accurate and reliable in the standard detection technology. This paper established detection method the standard Determination of glyphosate in soil and sediment, and to explore the effects of different soil physical and chemical properties of glyphosate detection, and in accordance with "environmental monitoring analysis method Technical guidelines for standard revision (HJ > 168) and "Interim National Environmental Monitoring Methods and standard system revision > (ring of letter [2009]10) requirements, the standard method for six lab experiments. The main research contents and results are as follows: (1) the establishment of soil and sediment in glyphosate analysis methods: the soil samples with three citric acid mixed solution of sodium 0.03 mol/L sodium phosphate and 0.01 mol/L extraction, ultrasonic extraction, using hydrochloric acid (HC1) solution was adjusted to pH 9 by n-hexane extraction purification, extract and 9- fluorene methyl chloroformate (FMOC-C1) derivatization reaction was carried out by liquid chromatography a fluorescence detector with acetonitrile /0.2% phosphoric acid water solution as mobile phase, detection of the sample. The sample preparation methods were optimized by phosphate and glyphosate competing adsorption sites in the soil, reduce the adsorption amount of glyphosate, and by adding metal ions Remove metal ion complexing agent sub complexation of glyphosate and soil, solve the difficult problem of glyphosate in soil extraction. This method has the advantages of simple operation, high sensitivity and good reproducibility. In 0.005 ~ 0.5 mg/L concentration range, the linear correlation coefficient R20.999 standard curve, soil samples the average recovery rate was 75%-100%, the relative standard deviation 15%. the detection limit was 0.01 mg/kg. The detection limit is 0.04mg/kg, recovery and detection limit can meet the requirements of agricultural soil environmental quality standard (0.5mg/kg). (2) through the comparison of soil humic acid content, soil pH value and seven kinds of heavy metal ions on recovery of glyphosate, explore the influence of soil the nature of glyphosate detection. The results show that the higher the content of organic matter in soil, the adsorption of glyphosate is stronger, the recovery rate is low; soil pH value of glyphosate recovery rate has a significant impact on the acid. In soil, glyphosate in molecular form, while in alkaline conditions, mostly in the form of anion repulsion, and soil particles with negative charge, reduce the adsorption of glyphosate in soil; heavy metal ions (Cu~ (2+), Fe~ (2+), Fe3+, Zn~ (2+). Ni~ (2+)) and Glyphosate can form a stable complex, the recovery rate decreased. And the heavy metal ion Co~ (2+) and Mn~ (2+) had no effect on glyphosate; detection method of glyphosate in soil and sediment can meet various types of soil and sediment. The effect of sodium phosphate and citric acid three sodium extract with buffer solution, pH can adapt to various environment and soil disturbance, citric acid three sodium ions can remove most of the heavy metals in soil. (3) according to the "technical guidelines for environmental monitoring and analysis methods of the revision of the standard (HJ > 168) and" national environmental pollutants monitoring The interim law revision of the standard system > (ring of letter [2009]10) requirements, the organization of the standard methods for 6 qualified laboratory validation of.6 laboratory verification results show that the detection limit was 0.011 mg/kg, the detection limit is 0.043 mg/kg. far below the national environmental quality standard limits (0.5 mg/kg) so, the detection limit of the method meet the current and future environmental standards. The method has better repeatability and reproducibility, repeatability limit for 0.016mg/kg-0.134 mg/kg in Hunan red soil, the reproducibility was 0.034mg/kg-0.299 mg/kg, average recovery matrix final value is 99.21% + 11.75%-101.15% + 9.60%; repeatability limit of paddy soil is 0.015mg/kg-0.139mg/kg. The reproducibility of 0.027mg/kg-0.214mg/kg matrix, the recovery rate of final value is 83.53% + 5.96%-88.79% + 4.11%; repeatability limit of black soil in Northeast China 0.016mg/kg-0.147mg/kg, reproducibility was 0 .020mg/kg-0.172mg/kg matrix, recovery of the final value of 79.96% + 10.09%-83.66% + 3.11%; repeatability limit before the lake sediment is 0.017 mg/kg-0.140 mg/kg 0.024 mg/kg-0.178 mg/kg, reproducibility, matrix recoveries of the final value of 75.31% + 9.70%-80.62% + 12.92%; repeatability limit the Qinhuai River sediment was 0.018 mg/kg-0.182 mg/kg, reproducibility was 0.022 mg/kg-0.208 mg/kg, the matrix recoveries of final values indicate that the 79.26% + 10.07%82.03% + 10.14%. results, the characteristic index of the standard method can achieve the desired requirements.

【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X839.2

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