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    固相萃取膜富集-超声解吸-气相色谱法测定地下水中有机磷农药的含量

    Determination of Organophosphorus Pesticides in Groundwater by Gas Chromatography with Enrichment on Solid Phase Extraction Membrane

    • 摘要: 应用以苯乙烯/二乙烯苯聚合物为吸附剂的固相萃取膜对地下水中6种有机磷农药(OPPs)进行富集。经解吸后所得解吸液直接用气相色谱法进行测定。取水样500 mL,加入甲醇2.5 mL,逐滴加入20%(体积分数)的盐酸溶液或200 g·L-1的氢氧化钠溶液调节水样的酸度至pH 6.0,将此溶液以100 mL·min-1的流量流经SDB-XC固相萃取膜,取下膜片,折叠后置于10 mL棕色小瓶中,加入丙酮2.0 mL,硫酸钠约0.2 g,盖紧瓶塞后于30℃条件下将膜片上吸附的6种OPPs超声解吸(7 min),使其溶于丙酮中。避光静置约5 min后,直接分取丙酮溶液0.50 mL,用气相色谱法测定其中OPPs的含量,采用火焰光度检测器。结果表明:6种OPPs的质量浓度在一定范围内与其对应的峰面积之间呈线性关系,其检出限(3S/N)均小于0.01 μg·L-1。以空白水样为基质,加入0.10 μg·L-1的OPPs的混合标准溶液,按上述方法进行7次平行测定,测定值的相对标准偏差在4.3%~7.6%之间。以3个实际样品为基体,分别加入3个浓度水平(0.050,0.10,0.70 μg·L-1)的6种OPPs混合标准溶液进行回收试验,测得6种OPPs的回收率均在76.0%以上。

       

      Abstract: Solid phase extraction membrane, with polymer of phenyethylene/divinyl benzene as adsorbent was used to enrich organophosphorus pesticides (OPPs) in groundwater, and after desorption from the membrane, the desorption solution of acetone was used directly in GC analysis. For enrichment and separation of 6 OPPs, 500 mL of water sample were taken, 2.5 mL of CH3OH were added, and the acidity of the sample solution was adjusted to pH 6.0 dropwise addition of φ 20% of HCl solution or 200 g·L-1 of NaOH solution. The solution was then passed through the SDB-XC solid phase extraction membrane at a flow-rate of 100 mL·min-1. The membrane was taken down, folded up and transferred into the 10 mL brown-glass bottle, 2.0 mL of acetone and about 0.2 g of Na2SO4 were added to the bottle which was then closed tightly with its ground stopper. The 6 OPPs adsorbed on the membrane were desorbed ultrasonically for 7 min at 30℃, and after keeping in dark for 5 min, an aliquot of 0.50 mL of the acetone solution was taken and amounts of the 6 OPPs were determined by GC with FPD. It was found that linear relationships between values of peak areas of the 6 pesticides and their mass concentrations in definite ranges were obtained, with their detection limits (3S/N) all less than 0.01 μg·L-1. 7 portions of testing sample with addition of 0.10 μg·L-1 of mixed standard solution of the 6 OPPs to blank water solutions as matrixes, were analyzed by the proposed method, and values of RSDs found were in the range of 4.3%-7.6%. Three water samples collected from various regional areas were taken as matrixs, and standard solutions of the 6 OPPs at 3 concentration levels (0.05, 0.10 and 0.70 μg·L-1) were added to each of the 3 samples, and recovery were tested by the proposed method, values of recovery found for each of the 6 OPPs were greater than 76.0%.

       

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