水果中氯氰菊酯残留量的测定

利用乙腈提取,弗罗里硅土填料净化的前处理方法,采用带电子捕获器（ECD）的气相色谱仪测定苹果、梨、黄桃中高效氯氰菊酯的残留量方法。本文以苹果、桃子、梨为样品,采用保留时间定性,外标法定量,结果表明：在0.0017μg.mL-1～0.028μg.mL-1范围检测线性关系良好,其线性相关系数为782.96。测定出高效氯氰菊酯在苹果、桃子、梨的残留量分别为：0.0012μg.mL-1、0.0090μg.mL-1、0.0179μg.mL-1。高效溴氰菊酯残留在不同水果中的添加回收率在98.1%～101.2%之间;其中苹果中高效溴氰菊酯平均添加回收率为99.3%;梨中高效溴氰菊酯平均添加回收率为99.2%;黄桃中高效溴氰菊酯平均添加回收率为99.6%;高效氯氰菊酯的变异系数为13.95%。通过对其准确度、灵敏度和精密度分析,确定气相色谱法分析农药残留的方法是可行的,可以作为针对农药残留的方法。本检测过程方便快捷,满足农药残留分析要求。     

GC-MS法测定小麦粉中溴氰菊酯的不确定度评定

通过建立数学模型,对气相质谱法测定小麦粉中的溴氰菊酯进行不确定度评定。对测定过程中不确定度来源进行分析,计算各不确定度分量,得到合成不确定度和扩展不确定度。结果表明,试样中溴氰菊酯含量为0.112 mg/kg,扩展不确定度为0.00650 mg/kg。方法测量不确定度主要由标准曲线的拟合、标准溶液的配制、重复性测量引入。称样、定容过程引入的不确定度可忽略。     

北京林地食用菌4种拟除虫菊酯类农药的残留监测和安全性评价

[目的]明确北京林地食用菌中氟氯氰菊酯、氯氰菊酯、溴氰菊酯和氰戊菊酯的残留水平。[方法]在北京市通州区、房山区、平谷区、昌平区林地共采集食用菌样品54个,用乙腈提取,N-丙基乙二胺(PSA)分散固相萃取剂净化,气相色谱配备电子捕获检测器分离测定,外标法定量。[结果]方法的平均回收率为69%~107%,相对标准偏差为1.8%~11.7%。采集的样品中,溴氰菊酯和氰戊菊酯的残留量均小于0.01 mg/kg,氟氯氰菊酯的检出率为20.4%,残留量为0.010~0.230 mg/kg,氯氰菊酯的检出率为68.5%,残留量为0.011~0.146 mg/kg。[结论]我国规定氟氯氰菊酯、氯氰菊酯、溴氰菊酯和氰戊菊酯在食用菌中的最大残留限量分别为0.3、0.5、0.2、0.2 mg/kg,以此为依据,北京林地食用菌中4种拟除虫菊酯类农药的残留是安全的。     

高效液相色谱法测定工作场所中溴氰菊酯含量的不确定度评定

对高效液相色谱法测定工作场所中溴氰菊酯含量的测量不确定度影响因素进行分析。构建溴氰菊酯的不确定度数学模型,分析在测量过程中会引入的各种不确定度的分量,并将其进行合成。     

气相色谱法测定水产品中溴氰菊酯残留量的不确定度评定

通过气相色谱法对水产品中溴氰菊酯残留量的测定过程进行不确定度评定,建立数学模型,分析各不确定度分量,计算出合成不确定度和扩展不确定度。结果表明,当样品中溴氰菊酯残留量为7.24μg/kg时,扩展不确定度为0.388μg/kg(k=2)。同时,经过对标准品、样品处理、重复检测及加标回收等因素的分析,发现标准溶液的配制和回收率是不确定度的主要来源。     

胡麻籽中溴氰菊酯残留的气相色谱检测

[目的]建立气相色谱测定胡麻籽中溴氰菊酯残留量的分析方法。[方法]胡麻籽样品采用乙腈提取,Florisil SPE小柱净化,气相色谱-电子捕获检测器(GC-ECD)检测。[结果]方法在0.01~5 mg/L范围内呈现良好的线性关系,相关系数为0.999 8。在0.2、0.5、1.0 mg/kg三个不同加标质量分数水平下,溴氰菊酯在胡麻籽中的添加回收率分别为90.6%、91.7%、92.4%,相对标准偏差(RSDs,n=5)均小于5%。[结论]该方法既能有效提取溴氰菊酯,又能最大限度减少油脂的干扰,净化效果良好,灵敏度高,结果准确,为胡麻产区科学合理使用溴氰菊酯提供参考。     

9种拟除虫菊酯类杀虫剂对瓜实蝇的产卵驱避作用测定

利用触角电位(EAG)和Y型嗅觉仪,测定瓜实蝇成虫对9种拟除虫菊酯类杀虫剂的EAG值,明确各药剂对瓜实蝇的驱避作用,并采用药剂处理苦瓜表面,统计药剂对瓜实蝇的产卵抑制作用。结果表明:9种药剂对瓜实蝇雌虫的EAG值均高于雄虫。溴氰菊酯对雌虫的驱避作用最强,驱避率为83.33%;氯氰菊酯、氯氟氰菊酯和联苯菊酯也具有良好的驱避作用。在25 mg/L质量浓度下,氯氰菊酯对瓜实蝇雌虫的产卵抑制率最高,为70.3%;其次是溴氰菊酯,产卵抑制率为68.83%。氯氰菊酯和溴氰菊酯对瓜实蝇雌虫具有较好驱避作用和产卵抑制作用,在生产上可作为瓜实蝇产卵驱避药剂使用。     

苹果果实各部位农药残留量的试验分析

用正己烷:丙酮=l:1(V/V)作提取剂,采用石英毛细管柱,电子捕获检测器,气相色谱法测定苹果果皮、果肉、果核中甲氰菊酯、氯氰菊酯、氰戊菊酯、溴氰菊酯农药残留量。对苹果果肉试验结果表明,甲氰菊酯的回收率为80.9%~103.6%,RSD为1.30%~5.18%;氯氰菊酯的回收率为86.1%~103.9%,RSD为1.32%~5.01%;氰戊菊酯的回收率为81.3%~102.9%.RSD为2.09%~5.30%;溴氰菊酯的回收率为80.1%~103.8%,RSD为2.43%~6.39%。试验结果表明苹果果皮、果肉、果核中农药残留量相差较大。     

气相色谱法同时测定烟叶中三种农药的残留

采用气相色谱法研究了仲丁灵、氯氰菊酯、溴氰菊酯3种农药在烟叶中的残留情况。样品经乙腈提取,Florisil硅土和中性氧化铝双吸附剂层析柱净化,正己烷-乙酸乙酯(98∶2,V/V)洗脱剂洗脱和浓缩后,采用GC-ECD进行定性和定量分析。当样品的加标水平为0.05,0.25,1.0 mg/kg时,加标回收率为73.8%～89.4%,相对标准偏差在5.5%～10.3%之间。该方法可用于烟叶中农药残留的快速分析测定。     

残杀威残留量测定的不确定度评定

依据NY/T 761.3-2004方法对残杀威残留量的测量不确定度进行分析和评定.分析结果表明:残杀威残留量测定的合成相对标准不确定度为3.62%.该测量过程所产生的测量不确定度主要来源于标样溶液配制、样品称量、样品稀释、样品溶液配制、标样溶液峰面积和样品溶液峰面积的测量,其相对标准不确定度分别为0.74%、0.023%、0.73%、0.30%、2.05%、2.78%.     

Effect of carbon black addition and its phase selective distribution on the stress relaxation behavior of filled thermoplastic vulcanizates

The long term mechanical behavior of thermoplastic vulcanizates (TPV) based on polypropylene (PP) and ethylene propylene diene terpolymer (EPDM) and different types and concentrations of carbon black (CB) has been characterized by means of stress relaxation experiments. Evaluation of the relaxation curves was carried out using the two‐component model allowing a division of the initial stress into different stress components which are caused by different networks available in TPV. The discussion focussed on the background of the stress components, which are originated by the CB addition, the non‐relaxing stress components σ, and σ, as well as the relaxing stress components Δσ^{CB(polymer‐layer)} and Δσ^CB(network). It was found that the concentration and type of CB as well as the phase specific CB distribution strongly affect the non‐relaxing and relaxing stress components. Up to a CB concentration of 9% in the EPDM phase the composite behaves as a thermo‐rheologically simple material because the impact of CB addition on the α‐relaxation of the crystalline PP phase is still negligible. A master curve was created by the horizontal shift of the relaxing stress curves Δσ^Comp(t) to a reference curve. At higher local CB loadings the additional relaxation processes induced by CB addition overlap with the α‐relaxation, thus, no master curve could be made in that case. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

三带模拟移动床对芍药苷及芍药内酯苷异构体的分离

介绍了应用三带模拟移动床分离得到高质量分数芍药苷和芍药内酯苷异构体的工艺。确定了模拟移动床分离芍药苷和芍药内酯苷的操作条件,SMBC运行模式:1-1-2,样品质量浓度:40 g/L,进样流速:UF=0.3 mL/min,洗脱流速:UD=2 mL/min,萃取流速:UP=4 mL/min,切换时间:ts=25 min,洗脱液及萃取液:V(甲醇)∶V(水)=30∶70。产品中芍药苷的质量分数根据标准曲线计算为92%,收率为85%;芍药内酯苷的质量分数为94%,收率为87%。讨论了影响模拟移动床分离的主要因素。     

CVDA设计曲线的试验研究

通过一系列宽板试验、带裂纹容器试验及工程容器典型事例分析,特别是高应变异形板试验、加筋宽板的有限元计算及大型容器接管裂纹测试研究与理论分析,作者发现无论是PD6493—80或JWES2805—83的设计曲线,在e/e_y=1附近,安全裕度均较小;特别是PD6493—80设计曲线的高应变区(e/e_y>1.5)的安全裕度却比低应变区要大得多;在同一设计曲线范围内,各段差异极大,显然是不合理的.本文提出了CVDA设计曲线为中国规范所采用.它的最后表达式为:经过理论分析及大量数据验证,充分说明了CVDA设计曲线的适用性、合理性和先进性.     

Alternating current and direct current conductivity of poly(azo-1,4-phenylene-vinylene-1,4-phenylene)

The electrical conductivity and dielectric properties of poly(azo-1,4-phenylene-vinylene-1,4-phenylene) were examined. The thermal activation energy of the direct current (DC) conductivity was compared with the activation energy of the relaxation process, evaluated from the area and the width of the curve of the dielectric loss factor against reciprocal temperature at constant frequency. The activation energy E_a=1.50 eV of the intrinsic DC conductivity was found to be roughly equal to the dielectric activation energy [1/H]=1,62 eV. The conduction mechanism in poly(azo-1,4-phenylene-vinylene-1,4-phenylene) is discussed.     

Development of internal structure of polymer-modified asphalts via transformations of the reduced frequency

The independent variable of dynamic material functions and corresponding master curves, the reduced angular frequency , was transformed into the apparent molecular weight MW*. As a function of MW*, the normalized master phase angle represented an apparent cumulative molecular weight. This function's numerical differentiation yielded the probability density function of the apparent molecular weight, f(MW*). While this procedure is unproblematic in conventional (straight run) asphalts, it is yielding peaks of negative MW* in polymer modified asphalts. Thus reduced frequency was also transformed to the temperature, which allowed us to determine that the apparent glass transition temperature as the maximum on the master curve of loss modulus G"(T). The master curve of the normalized phase angle as a function of temperature helped to explain the phenomenon associated with the probability density function in modified asphalts. The results presented in this article were obtained numerically, without the use of rheological models.     

Qualitative and Quantitative Evaluation of Quartz in Different Granular Types of Ouargla Region Sand Dunes – Algeria

In this paper, it is shown that Ouargla region (Algeria) sand dunes are very rich in quartz. This study aims to assess the quartz in the different granular sand types, using XRD spectroscopy. Granulometric classification and the size distribution curve were carried out. The X’Pert HighScore program based on the Rietveld refinement was used in analyzing the XRD data. Qualitative and quantitative quartz evaluations were carried out. It was deduced that the quartz was of the α phase. The concentrations of quartz have been calculated as: the very fine sand (0.063-0.100 mm) possessing the highest value of 82.05 %, followed by the coarse sand (0.500-1.000 mm) with 78 %, while in both the medium (0.250-0.500 mm) and the fine (0.100-0.250 mm) the concentration was about 67 %, whereas, the lowest one was 18.2 % in the very coarse sand (1-2 mm). These results were confirmed by FTIR spectroscopy. Crystallite sizes of quartz have been estimated, and their distribution curve versus grain sizes has been illustrated. It was found that the crystallite sizes in the fine sand are less than 100 nm, and thus may be considered as nanometric particles.     

二氮杂芴-9-酮的高效液相色谱分析

采用KromasilC18柱为分离柱 ,甲醇 -水 (体积比 6 0∶4 0 )为流动相 ,检测波长为 2 5 4nm ,苯乙酮做内标 ,对二氮杂芴 9 酮的含量进行了液相色谱定量检测。在 8～ 180 μg/mL峰面积 (y ,Ai/As)对标准溶液的质量浓度 (x ,μg/mL)线性关系良好 (r =0 99996 ) ,该法快速、准确     

纳米锑掺杂氧化锡制备中超临界CO_2干燥的工艺优化及动力学

纳米锑掺杂氧化锡(ATO)具有优越的光电性能,在制备过程中前驱体干燥处理至关重要。为掌握ATO前驱体的超临界CO2干燥工艺特性,研究了超临界干燥的时间、温度、压力和CO2流量等工艺参数对纳米ATO粒径、比表面积等的影响,进一步探讨了超临界CO2流量对干燥动力学的影响规律,并拟合了干燥曲线方程。结果表明:温度35~40℃、压力10~14 MPa、CO2流量1.2~1.8 L·h-1、干燥5~6 h,最终能够获得平均粒径20~30 nm、高比表面积的纳米ATO材料;流量对干燥速率有明显影响,醇分比0.4为干燥速率由恒速转为降速的临界点,醇凝胶干燥动力学方程能够很好地描述ATO醇凝胶干燥工艺过程。研究结果可为湿法制备纳米材料的湿凝胶干燥工业化生产和控制提供参考。     

快速离子色谱法检测卷烟主流烟气中的氨释放量

为了提高卷烟主流烟气中氨(NH3)的测定效率,对现行标准离子色谱法进行了改良,将标准工作曲线的拟合方式由一次线性拟合变为二次曲线拟合,同时优化了梯度洗脱程序,建立了卷烟主流烟气中NH3的快速离子色谱检测方法。结果表明:1采用快速梯度洗脱,15 min即可完成单个卷烟样品中NH3的测定,检测效率提高了近一倍;2NH+4在0.1~1.0 mg/L内二次回归系数良好(r2=0.999 4);检出限(LOD)为0.013μg/m L,定量限(LOQ)为0.045μg/m L;方法重复性好,RSD为1.99%;NH3的加标回收率为99.77%~102.29%;3该方法与现行烟草行业标准YC/T 377-2010的测定结果一致性较好。     

改性h-BN/聚氨酯丙烯酸酯涂料的制备与性能

利用水热法制备羟基化六方氮化硼（BNNSs）,采用异佛尔酮二异氰酸酯（IPDI）和丙烯酸羟乙酯（HEA）在其表面进行接枝得到功能化六方氮化硼（Fh-BN）。然后将得到的Fh-BN掺入有机硅改性的聚氨酯丙烯酸酯（PUA）涂料中,成功制备出改性h-BN/聚氨酯丙烯酸酯涂料。研究了水热时间、温度对BNNSs硼羟基含量的影响,利用XPS分析得出水热反应最佳反应条件为180℃、12h,B—OH质量分数达到5.97%。通过机械性能、综合热分析、耐水性、涂层交流阻抗和Tafel极化曲线进行测试分析,掺杂0.75%Fh-BN涂膜硬度达到3H,耐冲击性50cm,柔韧性0.5mm;与未掺杂前涂层相比,吸水率降低4.96%;涂层耐热性提高,T_50%提升了6℃;耐水测试浸泡168h后涂膜无变化;电化学测试表明：0.75%Fh-BN涂层阻抗R₁达到1.818×10⁹Ω·cm²,比原有涂层提升了两个数量级,E_corr由-0.4886V正移至-0.32124V,I_corr由2.5552×10^-7A/cm²降低至1.5555×10^-8A/cm²。Fh-BN的引入显著提升了涂层的机械性能、热稳定性和耐腐蚀性。