Uncertainty estimation in the analysis of pesticide residues in olive oil using data from proficiency tests

In this work we report the results for estimating the measurement uncertainty (MU) following up the application of two different approaches, relatively the top-down procedure, by using proficiency test data. We have focused the estimation on the olive oil matrix. We used the analytical data obtained from five selected editions of the Proficiency Tests (PTs, from 2007 to 2011) on pesticide residues in olive oil to estimate the MU. These PTs have been organized by Istituto Superiore di Sanità annually in cooperation with International Olive Council (IOC) since 1997. The number of participants in each trial ranged from 10 to 43. We used a total of 34 pesticide results. The expanded uncertainty U _(c) was calculated using a covering factor k = 2 for a confidence interval of 95%. In the approach 1, the within–laboratory reproducibility standard deviation is combined with estimates of the method and laboratory bias using PTs data. In the approach 2, the way of estimating the MU is based only on the bias that the laboratory has obtained participating in a sufficient number of the IOC proficiency tests. Comparing the relative expanded uncertainty based on these different approaches we notice values quite constant and close, from 42% to 48%. Moreover, these calculated expanded uncertainties are less than the default value of 50% (corresponding to a 95% confidence level), adopted from European guidance document SANCO based on the fit-for-purpose relative standard deviation (FFP-RSD).     

嗅觉实验配气方法的改进及影响因素研究

配制气体样品是异味测试及相关研究的基础工作,配气稳定性直接影响测试结果准确度。三点比较式臭袋法使用微量进样针量取并转移液体标准物质到3L无臭气袋的传统配气方法。对于异味阈值较小物质或样品浓度处于较低范围时,为了降低取样体积波动对配气精度和稳定性的影响。提出先将标准注入100mL玻璃注射器,充分挥发混匀后再转移部分气体到无臭气袋的两步式配气方法。结果表明,2种配气方法的准确度不存在显著差异,但两步式配气法的配气稳定性明显优于传统方法。此外,研究还发现,常见异味物质在被注人气袋后3min内便能完全挥发并混合均匀。除一些挥发性和吸附性极强的物质外,气袋内的异味物质气体浓度能在配好后20min内基本保持不变。     

Use of sensitive methods for detection of DNA damage on human lymphocytes exposed to p,p′-DDT: Comet assay and new criteria for scoring micronucleus test

Wide distribution, stability and long persistence in the environment of dichlorodiphenyltrichloroethane (DDT), probably the best-known and most useful insecticide in the world, imposes the need for further examination of the effect of this chemical on human health and especially on the human genome. In this study, peripheral blood human lymphocytes from a healthy donor were exposed to 0.025 mg/L concentration of p,p′-DDT at different time periods (1, 2, 24 and 48 h). For the assessment of genotoxic effect, the new criteria for scoring micronucleus test and alkaline comet assay were used. Both methods showed that p,p′-DDT induces DNA damage in low concentration used in this research. Results of micronucleus test showed a statistically significant (p < 0.05) genotoxic effect of p,p′-DDT on human lymphocytes compared with corresponding control and a different exposure time. A comet assay also showed increased DNA damage caused in p,p′-DDT-exposed human lymphocytes than in corresponding control cells for the tail length. Results obtained by measuring the level of DNA migration and incidence of micronuclei (MN), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) indicate the sensitivity of these tests and their application in detection of primary genome damage after long-term exposure to establish the effect of p,p′-DDT on human genome.     

Behavior of bensulfuron-methyl in an agricultural alkaline soil

A field experiment to determine the available bensulfuron-methyl (BSM) in the upper soil layer was conducted in an agricultural area in the South of Spain. To facilitate herbicide analysis, two application rates were employed, 200 g ha^?1 and 5 kg ha^?1. Samples of upper soil and soil solution were collected. Soil solution was sampled by means of metallic samplers, placed at a depth of 35 cm. In the plots receiving the lower dose ceramic suction, porous cups were also installed. Results from soil solution samples showed that the maximum BSM concentration was found after 8-10 days for the high irrigation supply (945 mm) and after 18-25 days for the lower irrigation regime (405 mm). The mathematical model FOCUSPELMO 1.1.1 was applied to interpret the data obtained in the field experiments. In general, there was a reasonable agreement between experimental and simulated data for soil samples, although the model did not acceptably predict herbicide concentrations in water soil samples. Ceramic cups sampled a higher soil water volume and more frequently than did the metallic samplers. However some variable results were attributed to preferential flow.     

The effects of soil and Trifolium repens (white clover) on the fate of estrogen

In this study, we investigated the behavior of estrogens in the rhizosphere of white clover (Trifolium repens, clover hereafter) with two different pot tests, using soil and agar as growth media. In a pot test using agar spiked with estrogen, the estrogen concentration in the agar with clover decreased to non-detectable levels within one month, while in the agar without clover, 60% of initially added estrogen remained after one month. The half-lives of estrone (E1) and 17β -estradiol (E2) in the agar with clover were 2.4–3.8 and 13.2 d, respectively. The dissipation of E1 followed first-order rate law, while that of E2 fitted a zero-order reaction, indicating that they had different mechanisms of dissipation from agar. In the soil pot test, the behavior of E1 and E2 was not influenced by clover. An initial rapid decrease in the amount of estrogen extracted by methanol/acetic acid was followed by persistence for 1–3 months, regardless of presence of clover. Moreover, in three weeks E1 and E2 were only partly degraded by microbes extracted from the soil used in the pot test. In this study, abiotic degradation of estrogens and sorption of estrogen to soil, rather than the effects of soil microbes and clover, contributed to the initial rapid dissipation of estrogens in the soil. However, the results of the agar pot test suggested that vegetation such as clover may significantly contribute to removal of estrogens when estrogens in aqueous phase are discharged with surface runoff and preferential flow after heavy rain in agricultural fields, or when present in soils with low estrogen sorptivity.     

柠檬酸浸出土壤中铜、锌的优化设计

以某工业废弃地土壤为供试材料,采用批次实验方法,研究了柠檬酸对重金属Cu、Zn的浸出效果。并在单因素实验基础上,探讨不同pH值、柠檬酸浓度、固液比和浸提时间等对浸出效果的影响,进而对实验条件进行正交优化组合,确定优化工艺参数为：pH值为3.2,柠檬酸浓度为0.4 mol/L,壤土固液比为1/10,土壤中Cu、Zn接近平衡的时间分别为1 h和1.5 h。结果表明,在此条件下,对这2种金属来说,Cu较Zn易释放,Cu、Zn的最大浸出率分别为74.8%和65.3%。柠檬酸浸提前后,土壤中有机质含量下降范围为0.61%~3.16%。单从土壤有机质含量来看,柠檬酸对土壤质量影响较小,具有较好的应用前景。     

典型危险废物的工程力学特性

掌握填埋废物的工程力学特性是确保危险废物填埋堆体稳定性的重要前提条件,因此,针对6种典型危险废物的工程力学特性开展了调查研究.研究结果表明,污泥类危险废物的含水率和有机质含量远高于非污泥类危险废物,而前者的比重则显著低于后者.污泥类危险废物的渗透系数相对较小,比污染土壤和飞灰炉渣混合物的渗透系数小1个数量级,比滤池填料的渗透系数小2个数量级.不同危险废物的无侧限抗压强度排序为:飞灰炉渣混合物(314.3 kPa)和滤池填料(278.9 kPa)＞污染土壤(124.9 kPa)＞杭州氧气厂污泥(68.6 kPa)、锌铬污泥(71.4 kPa)、油泥(58.4 kPa).不同危险废物的粘聚力排序为:飞灰炉渣混合物(40.8 kPa)、滤池填料(31.1 kPa)＞污染土壤(20.9 kPa)＞杭州氧气厂污泥(1.94kPa)、锌铬污泥(3.10 kPa)、油泥(1.81 kPa).此外,不同危险废物的内摩擦角差异相对较小,其变化范围在18.8°～35.0°之间.综合分析可知,飞灰炉渣混合物和滤池填料的工程力学特性较好,而污泥类危险废物的工程力学特性则较差.     

膨化预处理玉米秸秆的还原糖酶解工艺

应用膨化技术对玉米秸秆进行预处理.在单因素实验基础上,以还原糖转化率为影响值设计正交实验,研究温度、pH、液固比、酶浓度及酶解时间五因素对纤维素酶解过程的影响.得出玉米秸秆糖化酶解最佳工艺条件为:温度48℃,pH 4.5,液固比8:1,酶浓度36.0 U/g,酶解时间25 h;在此工艺条件下还原糖转化率达到28.98％.扫描电镜表征对比观察可看出,膨化后玉米秸秆纤维素酶解充分;结合红外光谱对各组分特征基团分析表明,膨化后的玉米秸秆酶解的纤维素基团特征峰变化更为明显.     

水泥、粉煤灰及DTCR固化/稳定化重金属污染底泥

采用水泥、粉煤灰及有机硫稳定剂DTCR固化/稳定化处理重金属污染的底泥,考察固化体的抗压强度及重金属浸出毒性,确定了底泥固化/稳定化的最佳工艺条件。结果表明:仅用水泥固化/稳定化重金属污染底泥,固化体抗压强度随水泥用量的增加而上升,重金属浸出浓度则下降,当水泥∶干底泥质量比为0.6∶1.0时,固化体7 d抗压强度能达到0.99 MPa的标准值;进一步研究发现,水泥∶粉煤灰∶干底泥质量比为0.54∶0.06∶1.0时,重金属浸出浓度有所上升,但7 d及28 d抗压强度仍能分别达到1.2 MPa和2.8 MPa;加入DTCR后,当水泥∶粉煤灰∶DTCR∶干底泥质量比为0.54∶0.06∶0.012∶1.0时,固化体7 d及28 d抗压强度分别为1.1 MPa和2.1 MPa,醋酸缓冲溶液法浸出的Cd、Pb、Zn和Cu浓度分别为0.102、0.189、0.180和0.032 mg/L。     

国产脱硝催化剂在国电长源荆州电厂2×300MW机组上的应用

随着新火电厂大气污染物排放标准的出台,NOx排放标准提高,现有的脱硝技术难以满足要求,需要增加后端烟气脱硝处理技术.选择性催化还原法是较成熟的烟气脱硝技术,催化剂是SCR技术的核心.针对国内某催化剂在国电长源荆州电厂的应用情况,详细描述了催化剂的设计选型过程.运行结果表明,该催化剂完全可以满足长源荆州电厂的性能要求,说明国产脱硝催化剂的设计选型、生产以及运行等技术能力已达到要求.