固相萃取-超高效液相色谱-串联质谱测定水中痕量苯甲地那铵

苯甲地那铵是一种广泛使用的苦味剂,近年来被发现在欧洲水体中普遍存在。建立灵敏可靠的环境样品前处理分析方法对评价其环境行为具有重要意义。通过优化关键前处理过程参数,建立了水中苯甲地那铵的固相萃取-超高效液相色谱串联质谱分析方法,系统考察了该方法的准确度、精密度、基质效应、检出限以及线性范围。研究表明：当调节水样pH至8以上,采用混合型阳离子交换小柱(200 mg, 3 mL)富集水样,采用含体积分数2%甲酸的甲醇溶液洗脱时,该方法可获得最佳回收率;纯水和环境水样中加标回收率分别为97%～105%和89%～119%,相对标准偏差小于7%;基质效应均在24%以内;方法检出限为0.07 ng/L,线性范围为0.01～50μg/L。该方法可用于环境水体中苯甲地那铵的痕量检测。     

Residues and dissipation of the pesticide emamectin benzoate under Egyptian field condition: a case study

A simple, rapid analytical procedure for the quantification of emamectin benzoate in tomato was developed using high performance liquid chromatography with fluorescence detector (HPLC-FLD). Emamectin benzoate residues were extracted from tomato samples with n-hexane:ethyl acetate (1:1, v/v). The method involved derivatization using trifluoroacetic anhydride and 1-methylimidazole, prior to analysis by HPLC-FLD. Limit of quantification of this method was found to be 0.01 mg/kg, while limit of detection was 0.005 mg/kg. The dissipation of emamectin benzoate on tomato was studied, and half-life (t_1/2) was estimated in a field study carried out at three different locations. Emamectin benzoate was sprayed on tomato at recommended dosage. Samples of tomato were collected at 0, 1, 3, 7, 10, and 15 days after treatment. The t_1/2 of emamectin benzoate when applied at the recommended doses in tomato was approximately 2.5 days. The residue of emamectin benzoate reached below the maximal residue limit (MRL) 10 days after spraying at the tested dosage. Hence, a safe pre-harvest interval of 10 days is suggested before harvesting of tomato. This study would also be helpful for the Egypt government to establish the MRL of emamectin benzoate in tomatoes and provide guidance on the proper and safe use of this insecticide.     

两种苯甲酸处理系统细菌群落结构的ARDRA分析

利用ARDRA(扩增rDNA限制性分析)的方法对两种驯化条件产生的苯甲酸活性污泥中细菌的群落结构进行了分析。提取污泥样品总DNA以后,利用细菌16SrDNA通用引物进行PCR扩增。结果显示:两种活性污泥分别有20.4%和24.3%的酶切类型是自身特有的,可见在微生物群落结构上差别显著。并且利用这种方法分别检测到了103和107种的微生物类型,而利用传统的纯培养手段则只分别分离到了7种和8种微生物,分别只占ARDRA方法的6.8%和7.5%,充分显示了分子生物学的方法在进行微生物群落结构研究方面所具有的优越性。     

试验方法和接种物来源对苯甲酸钠快速生物降解率的影响

化学品的快速生物降解性直接影响其在环境中的迁移、转化和归宿,是鉴别其环境危害性和持久性的基本指标,是政府管理部门对化学品进行风险管理的重要科学依据,在生态毒理测试中具有非常重要的地位。为探讨试验方法、接种物来源以及两者的交互效应对苯甲酸钠生物降解率的影响,2013—2015年间以广州地区2个主要处理生活污水的污水处理厂(DTS、LD)为接种物来源,采用OECD 301系列试验方法(301B、301D和301F)进行了苯甲酸钠的快速生物降解性试验,共获得89个标准化测试数据。统计分析结果显示,接种物来源、试验方法与接种物来源的交互效应对苯甲酸钠生物降解率影响不显著,但试验方法单一因素的影响显著。本研究表明,当受试物为易生物降解时,接种物来源、试验方法和接种物来源的交互效应对该受试物的生物降解率无显著的影响,但在同一条件下,选择不同的试验方法往往会导致最终生物降解率出现明显差异。     

Benzoate degradation by Rhodococcus opacus 1CP after dormancy: Characterization of dioxygenases involved in the process

The process of benzoate degradation by strain Rhodococcus opacus 1CP after a five-year dormancy was investigated and its peculiarities were revealed. The strain was shown to be capable of growth on benzoate at a concentration of up to 10 g L^?1. The substrate specificity of benzoate dioxygenase (BDO) during the culture growth on a medium with a low (200–250 mg L^?1) and high (4 g L^?1) concentration of benzoate was assessed. BDO of R. opacus 1CP was shown to be an extremely narrow specificity enzyme. Out of 31 substituted benzoates, only with one, 3-chlorobenzoate, its activity was higher than 9% of that of benzoate. Two dioxygenases, catechol 1,2-dioxygenase (Cat 1,2-DO) and protocatechuate 3,4-dioxygenase (PCA 3,4-DO), were identified in a cell-free extract, purified and characterized. The substrate specificity of Cat 1,2-DO isolated from cells of strain 1CP after the dormancy was found to differ significantly from that of Cat 1,2-DO isolated earlier from cells of this strain grown on benzoate. By its substrate specificity, the described Cat 1,2-DO was close to the Cat 1,2-DO from strain 1CP grown on 4-methylbenzoate. Neither activity nor inhibition by protocatechuate was observed during the reaction of Cat 1,2-DO with catechol, and catechol had no inhibitory effect on the reaction of PCA 3,4-DO with protocatechuate.     

稳健统计在快速生物降解性试验质量分析中的应用

快速生物降解性试验在新化学物质的生态毒理测试中占据重要地位,其测试数据的可靠性直接影响后续的测试策略和物质的申报登记、以及新化学物质进入环境后的风险管理。为研究OECD 301系列试验(301B、301D和301F)的质量,选用本机构近5年来积累的标准化物质苯甲酸钠14 d快速生物降解率数据,首次采用稳健统计技术,以稳健总计统计量的Z比分数作为评价指标,对各试验数据和试验系统的质量开展评估。结果显示,当301B、301D和301F试验的苯甲酸钠降解率分别在63.8%~88.0%、63.4%~89.2%和66.0%~99.8%范围内时,表明测试结果满意,该批次试验数据质量良好;若苯甲酸钠降解率不在此范围,则表明测试结果可能存在问题,甚至得到的可能是错误数据,需要进一步验证。据此提出了对实际测试工作具有指导意义的质量分析对照表,以期为测试机构开展新化学物质快速生物降解性试验时的质量分析提供参考。     

Acute toxicity of three avermectins to anuran tadpoles北大核心CSCD

Avermectins are a new class of macrocyclic lactones derived from mycelia of the soil actinomycete, and are among the most effective agricultural pesticides and antiparasitic agents. In this report, three avermectins (abamectin, ABM; ivermectin, IVM; and emamectin benzoate, EMB) were used to assess their toxic effects on tadpoles of four anuran species (Duttaphrynus melanostictus, Hylarana guentheri, Polypedates megacephalus and Microhyla heymonsi) using a static-renewal acute toxicity test. The results showed that there were significant dose-responsive correlations between the accumulated dead probit of tadpoles and the concentrations of the three avermectins. The 96-h half lethal concentrations (LC50) of ABM to the tadpoles of the four species were 0.042, 0.034, 0.020, and 0.014 mg/L; the 96-h LC50 values of IVM were 0.029, 0.012, 0.012, and 0.006 mg/L, and the values of EMB were 0.118, 0.111, 0.122, and 0.089 mg/L, respectively. Our study reveals that these agrochemicals probably make a significant contribution to the decline of amphibian populations, and provides valuable information about the toxic effects of avermectins on amphibians. © 2018 Science Press. All rights reserved.     

甲氨基阿维菌素苯甲酸盐对海洋桡足类日本虎斑猛水蚤的急慢性毒性效应

甲氨基阿维菌素苯甲酸盐(简称甲维盐)是一种广泛应用于农业和水产养殖业的高效抗生素杀虫剂,会进入近海海洋环境从而对海洋生物造成影响。为初步探讨甲维盐对海洋桡足类产生的生物效应,研究了甲维盐对日本虎斑猛水蚤(Tigriopus japonicus Mori)的死亡率、摄食率、滤水率、神经传导关键性酶和抗氧化防御系统中多种酶活性以及生殖、发育的影响。结果显示,甲维盐对于日本虎斑猛水蚤有显著的急性毒性影响,雌性成体和雄性成体的96 h-LC_(50)分别为7 156μg·L~(-1)和3 637μg·L~(-1);雌性成体的24 h-EC_(50)为3.5μg·L~(-1)。暴露在不同甲维盐浓度(0.5、1、2、3.5和5μg·L~(-1))条件下24 h后,日本虎斑猛水蚤的摄食率和滤水率随甲维盐浓度升高逐渐降低,乙酰胆碱酯酶(AchE)活性、抗氧化酶超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GPx)活性均随甲维盐浓度的升高先升高后趋于平稳,而过氧化氢酶(CAT)活性无显著变化。日本虎斑猛水蚤连续暴露2个世代,随着甲维盐浓度的升高,发育率逐渐降低;当甲维盐浓度达到0.5μg·L~(-1)时,10 d产卵量受到显著抑制,这说明甲维盐对其种群繁衍能力产生了显著影响。将第3代无节幼虫置于海水中进行恢复培养后发现,高浓度甲维盐暴露(0.5μg·L~(-1))对日本虎斑猛水蚤发育和生殖均造成了不可逆的影响,毒性可能具有不可恢复性。本文可为评估甲维盐对海洋桡足类的潜在影响提供基础数据和依据。     

GC/MS法测定食醋中对羟基苯甲酸乙酯、对羟基苯甲酸丙酯

用气相色谱质谱联用法测定食醋中对羟基苯甲酸乙酯和对羟基苯甲酸丙酯,实验结果表明方法简便快速,准确可靠,稳定性好.     

Reactive oxygen species metabolism during the cadmium hyperaccumulation of a new hyperaccumulator Sedum alfredii （Crassulaceae）

Sedum alfredii Hance, a newly discovered hyperaccumulator, could serve as a good material for phytoremediation Cd polluted sites. Malondialdehyde (MDA), reactive oxygen species (ROS) and antioxidases (catalase (CAT); superoxide dismutase (SOD); peroxidase (POD)) in the leaf were determined when S. alfredii was treated for 15 d with various CdCl2 concentrations ranging from 0 to 800 μmol/L. The results showed that the production rate of 2′,7′-dichlorofluorescein (DCF), which is an indicator of ROS level, reached up to the maximum at 400 μmol/L CdCl2 and then declined with the increase of CdCl2 concentration, while MDA accumulation tended to increase. CAT activity was significantly inhibited at all tested CdCl2 concentrations and SOD activity was sharply suppressed at 800 μmol/L CdCl2. However, the enhancement of POD activity was observed when CdCl2 concentration was higher than 400 μmol/L. In addition, its activity increased when treated with 600 μmol/L CdCl2 for more than 5 d. When sodium benzoate, a free radical scavenger, was added, S. alfredii was a little more sensitive to Cd toxicity than that exposed to Cd alone, and the Cd accumulation tended to decline with the increase of sodium benzoate concentration. It came to the conclusions that POD played an important role during Cd hyperaccumulation, and the accumulation of ROS induced by Cd treatment might be involved in Cd hyperaccumulation.