蔬菜和水果中有机氯类，拟除虫菊酯类农药多残留检测方法

蔬菜和水果中有机氯类，拟除虫菊酯类农药多残留的测定，现行2003版国标中给出的测定方法，目标单一，针对性过强，与日益严峻的食品质量安全要求不相适应，不能满足现代多种类农药多残留的检测，本文介绍的方法是基于农业部蔬菜和水果中有机氯类、拟除虫菊酯类农药多残留检测方法试料制备的基础上，选定了最佳测定条件，让有机氯类，拟除虫菊酯类中共15种物质在相同仪器条件下一次性出峰、且峰之间的分离度大于1．40全过程仅耗时50min左右，且用二种不同型号的仪器同种型号的毛细管柱共同验证，结果满意。     

高效液相色谱法检测食品接触材料中三聚氰胺的残留量

建立了一种用液相色谱技术检测分析食品接触材料中三聚氰胺残留量的方法。样品采用0.1 mol/L盐酸作为提取溶液,70℃水浴超声提取。色谱分离采用NH2柱,流动相为V(乙腈):V(5mmol/L磷酸盐缓冲溶液,pH 6.5)=75:25,二极管阵列检测器检测。在优化条件下,三聚氰胺浓度在0.2-100 mg/L范围内与其峰面积线性关系良好,检出限(S/N=3)为0.02 mg/L。在100μg的添加水平下,三聚氰胺的回收率在80-99%之间,相对标准偏差(RSD)为2.80-4.32%。揭示了原料中三聚氰胺残留量与成型品的三聚氰胺迁移量的正相关关系。结果表明,该法简便、快速,可准确测定食品接触材料中三聚氰胺残留量。     

HPLC法快速测定竹凉席中的罗丹明B

建立了快速测定竹凉席中染色剂罗丹明B的含量的方法。以甲醇水溶液超声提取,用高效液相色谱法(荧光检测器)测定,峰面积外标法定量,在优化条件下,罗丹明B的质量浓度在0.5~100.0ng/m L范围内与色谱峰面积呈现良好的线性关系,线性相关系数r=0.9999,检出限为3.0ng/L,加标回收率为87.0%~100.2%,得到罗丹明B的质量浓度和保留时间的相对标准偏差分别为1.24%和0.05%。该方法样品处理简单、快速,适用于竹凉席中罗丹明B的日常检测。     

水中爆炸下轨条砦表面压力测试及分析

轨条砦表面压力的测试及分析对研究水中爆炸载荷激励下轨条砦内部响应传播规律具有重要意义。论文开展浅水中远距离爆炸载荷作用下轨条砦表面压力的测试,炸药为3 kg的B炸药。通过对测得水中自由场爆炸冲击波压力峰值进行经验公式拟合,对比分析轨条砦表面压力峰值及水中自由场压力峰值。研究结果表明：在轨条砦各表面中迎爆面的压力峰值远超其他壁面。在同种炸药相同距离工况下,轨条砦表面压力明显大于水中自由场爆炸冲击波压力峰值,造成这种结果的主要原因是水中冲击波在轨条砦结构表面产生复杂的反射、绕射作用。轨条砦表面压力的测试及分析对爆炸载荷下水中障碍物表面压力的测试及毁伤分析具有一定参考性。     

液相色谱串联质谱测定鳗鱼中硝基呋喃的含量

硝基呋喃类药物及其代谢产物可使实验动物发生癌变、基因突变,同时具有生殖毒性,可能对人体产生危害。因此,硝基呋喃含量的检测在食品安全中是至关重要的,本文采用液相色谱串联质谱技术检测四种硝基呋喃类代谢物。硝基呋喃类代谢物在酸性条件下经过2-硝基苯甲醛衍生化,用乙酸乙酯提取纯化,电喷雾离子化,液相色谱-串联质谱检测。结果表明,四种硝基呋喃类药物的色谱峰面积与浓度在0.1～10.0 ng/mL范围内均呈现很好的线性关系,该方法具有操作简便、灵敏、准确等优点。     

水下爆破破冰爆炸冲击波传播规律数值分析

利用动力分析软件ANSYS/LS-DYNA模拟研究水下爆破破冰过程中爆炸冲击波压力的作用特征和传播规律,对比分析在冰体覆盖的相对封闭条件和常规水下爆炸时水中压力变化的差异性。研究表明:爆炸冲击波产生的水压力以炸药为中心向四周传播,对冰面破碎起主要作用,被扰动冰体主要发生振动折裂。炸药周围近区压力初始峰值大体上相同,爆源远区相差较大,冰盖的存在减弱了爆破能量的耗散。对于相同集中药包,入水深度直接影响爆破破冰效果。和常规水下爆炸相比,在冰体覆盖的相对封闭条件下水中峰值压力较小,衰减速度较慢。     

精制棕榈油制备生物柴油的实验研究

以精制棕榈油为原料,与无水乙醇进行酯交换反应制取生物柴油。探讨了反应物配比、催化剂用量、温度、反应时间等因素对产物产率的影响,采用正交实验优化合成条件确定了最佳合成条件及影响反应的关键因素,并运用气相色谱-质谱技术分析了产物的结构和组成,运用核磁共振技术对主要成分进行了结构确定。结果表明该生物柴油符合《柴油机燃料调和用生物柴油国家标准》(GB/T20828-2007),接近美国和德国的生物柴油标准,基本符合《轻柴油》(GB252-2000),适于中小规模及大规模生产应用。     

羧甲基纤维素钠对鳞片石墨颗粒分散效果的影响

针对石墨具有天然的憎水性,单纯的石墨颗粒不易在水中分散,必须添加亲水性物质作为分散剂的问题,以羧甲基纤维素钠为分散剂,在相同的工艺条件下制备石墨-水系浆料,研究羧甲基纤维素钠用量及分散时间对鳞片石墨颗粒在水中分散效果的影响。结果表明,羧甲基纤维素钠的质量分数为1%,球磨分散时间为20 min,鳞片石墨颗粒在水中的分散效果最好。     

一种基于广义互相关的水声直扩信号检测方法

直扩信号因其低功率谱密度特性使得检测十分困难,针对传统自相关法在低信噪比条件下检测性能急剧下降的问题,在分析了直扩信号自相关特性的前提下,提出一种基于广义互相关估计的直扩信号检测方法。首先对接收信号分段并对相邻信号段分别进行广义互相关估计,估计结果采用二阶矩非相干积累,提取相关峰获得检测统计量,将检测统计量与门限比较,判定信号是否存在。通过计算机仿真对比了改进自相关检测法与文中方法的检测性能,仿真结果表明：该方法相比于改进自相关检测法信噪比容限降低了5 dB,适用于低信噪比条件下的水声直扩信号检测。水池试验处理结果也验证了该方法的实用性。     

基于神经网络和功率谱的水中目标信号检测方法

将功率谱和神经网络相结合，应用于高海况、低信噪比条件下，水中目标信号的特征提取中．文中首先对信号进行功率谱估计，利用目标信号功率主要集中在低频部分的特点，提取低频信号的能量作为特征，然后利用人工神经网络对目标信号进行检测．利用不同浪级情况下海洋水压场的仿真信号数据，对某型目标舰船的水压信号进行了检测计算，验证了该方法的有效性，尤其是达到了在高海况、低信噪比条件下，对目标信号检测率比较高、虚警率比较低的效果．     

Wood gas generators for small power (∼ 5 hp) requirements

This paper reports experimental and developmental studies on wood gas generators meant for running 5 hp diesel engines in irrigation water pumping. Critical inputs for the design of small reactors are presented. A prototype of the gas generator based on these inputs has been built and tested along with a diesel engine pumpset. The results of various tests on the system are described along with some critical operational features. The lowest amount of diesel at which the engine could be run with a mixture of diesel and gas is about 15% of the consumption with diesel alone. However, to obtain the same energy, that is the same amount of water at a given height, the best replacement of diesel obtained is about 75%. The paper also comments on the economics of such systems. The results presented here are the outcome of a project ‘Wood gas generators for engines of less than 10 hp’ financed and administered by Karnataka State Council for Science and Technology, Indian Institute of Science, Bangalore.     

Contribution to the gas chromatographic analysis for both refrigerants composition and cell gas in insulating foams – Part I: Method

In this paper, an easy low cost chromatographic analysis for both refrigerants blend composition and cell gas in insulating foams is presented. This work firstly deals with the measurement protocols for these substances. The presented protocols are simple, likely to be used by non-specialists of chemical analysis (i.e. by refrigeration engineers). Among other methods, gas chromatography was used for separation and detection of halocarbons. For refrigerants extracted from refrigeration plants, the analysis requires a prior oil separation. As for insulating foams, analysis of cell gas composition is processed with the same protocol. Sampling remains of main importance; two possible sampling methods were validated and compared. Finally, the interest in the analysis method is illustrated with the example of a real application: study of the distillation phenomenon of a zeotropic refrigerant in an industrial refrigeration plant with flooded evaporators. The results are discussed for their consequences on the working performances of the refrigerating system. In part II, we propose original results obtained with that method to study the aging of insulating foams.     

Using comprehensive two-dimensional gas chromatography retention indices to estimate environmental partitioning properties for a complete set of diesel fuel hydrocarbons

Comprehensive two-dimensional gas chromatography (GCxGC) provides nearly complete composition data for some complex mixtures such as petroleum hydrocarbons. However, the potential wealth of physical property information contained in the corresponding two-dimensional chromatograms is largely untapped. We developed a simple but robust method to estimate GCxGC retention indices for diesel-range hydrocarbons. By exploiting n-alkanes as reference solutes in both dimensions, calculated retention indices were insensitive to uncertainty in the enthalpy of gas-stationary-phase transfer for a suite of representative diesel components. We used the resulting two-dimensional retention indices to estimate the liquid vapor pressures, aqueous solubilities, air-water partition coefficients, octanol-water partition coefficients, and vaporization enthalpies of a nearly complete set of diesel fuel hydrocarbons. Partitioning properties were typically estimated within a factor of 2; this is not as accurate as some previous estimation or measurement methods. However, these relationships may allow powerful and incisive analysis of phase-transfer processes affecting petroleum hydrocarbon mixtures in the environment. For example, GCxGC retention data might be used to quantitatively deconvolve the effects of water washing and evaporation on environmentally released diesel fuels.     

厦门地表水油污染的油种指纹鉴定

厦门地表水主要有从九龙江取水的北溪引水渠和坂头水库等,系厦门饮用水源。为保证自来水水质,自1989年至1994年开展厦门地表水水质调查,无论定期取样或临时抽样,早期均发现有石油烃污染。经带毛细管色谱柱的程序升温气相色谱作正构烷烃油种指纹鉴定,为船舶的柴油和汽车的机油、废油污染地表水。其中还检出如苯并(α)芘等多环芳香烃化合物,经美国罗得岛大学海洋研究生院有机地球化学实验室测定确认了这一结论。通过有关方面进行污染源治理,现水质得以恢复,自来水中苯并(α)芘已符合饮用水标准。     

Determination of naphthenic acids in crude oils using nonaqueous ion exchange solid-phase extraction

A method is presented for the routine, rapid, and quantitative analysis of aliphatic and naphthenic acids in crude oils, based on their isolation using nonaqueous ion exchange solid-phase extraction cartridges. The isolated acid fractions are methylated and analyzed by gas chromatography and gas chromatography/mass spectrometry. The method is effective on both light and heavy oils and is capable of providing mechanistic information of geochemical significance on the origin of the acids in the oils. Analysis of oils that were solvent extracted from laboratory and field mesocosm marine sediment oil degradation studies indicate that this new method of analyzing the products of hydrocarbon biodegradation may be a useful tool for monitoring the progress of bioremediation of oil spills in the environment.     

Thermal treatment of soils contaminated with gas oil: influence of soil composition and treatment temperature

Samples of two soils containing different organic matter contents, neat or contaminated with gas oil (diesel fuel oil) at 2.5 wt.% were heated from room temperature to different final temperatures (200-900 degrees C). The experiments, performed in an anaerobic media, simulate conditions pertinent to ex situ thermal desorptive and thermal destructive treatments. The products generated during the heating were collected and light gases were analyzed by gas chromatography. The results indicate that the chemical composition of the soil is a key factor since it strongly influences the quantity and composition of the off-gases. According to the liquid and light gas yields, the gas oil does not affect appreciably the generation of pyrolysis products of the own soil constituents and the gas oil does not suffer significant chemical transformations even at high operating temperatures (e.g. 900 degrees C). With surface areas of 16000 cm(2)/g (Soil A) and 85000 cm(2)/g (Soil B) based on the monolayer adsorbed model, 4 and 20%, respectively, of the original gas oil can be adsorbed. These values are in good agreement with experimental data. Even for high temperatures, the employed thermal treatment is capable to practically remove the gas oil from the soil bed without changing appreciably the original chemical composition of the contaminant.     

基于幂指数法预测柴油十六烷值

为了实现十六烷值的快速检测,减少标准燃料的使用量,采用幂指数方法建立了预测柴油十六烷值的数学模型,将幂指数法计算的十六烷值与实测十六烷值进行比较。针对不同组成的柴油进行预测,得到不同种类柴油的最大预测误差,找到了与预测模型匹配程度高的柴油种类,进行有针对性的十六烷值预测。同时,对提出的数学模型的预测结果进行了校正,通过校正可进一步提高幂指数拟合法的精度,并给出十六烷值水平在45时的校正系数k为0.991。幂指数法可减少标准燃料样品的使用量,减少台架试验成本。     

吸收法测定液化石油气中二甲醚含量

利用二甲醚与石油产品水溶性的差异,采用水吸收法测定石油产品中二甲醚含量,此方法简单、易行,完全可代替气相色谱法检测石油产品中二甲醚的含量。     

Quasi-simultaneous acquisition of hard electron ionization and soft single-photon ionization mass spectra during GC/MS analysis by rapid switching between both ionization methods: analytical concept, setup, and application on diesel fuel

This work describes the realization of rapid switching between hard electron ionization (EI) and soft single-photon ionization (SPI) integrated in a compact orthogonal acceleration time-of-flight mass spectrometer. Vacuum-ultraviolet (VUV) photons of 9.8 eV (126 nm) emitted from the innovative electron-beam-pumped rare-gas excimer light source (EBEL) filled with argon are focused into the ion chamber by an ellipsoidal mirror optic for accomplishing of SPI. This novel orthogonal acceleration time-of-flight mass spectrometer with switching capability was hyphenated to one-dimensional gas chromatography (GC) and comprehensive two-dimensional (2D) gas chromatography (GC × GC) for the first time. Within this demonstration study, a maximum switching frequency of 80 Hz was applied for investigation of a mineral-oil-type diesel sample. This approach allows the quasi-simultaneous acquisition of complementary information about the fragmentation pattern (EI) as well as the molecular mass (SPI) of compounds within a single analysis. Furthermore, by application of a polar GC column for separation, the SPI data can be displayed in a 2D contour plot, leading to a comprehensive 2D characterization (GC × MS), whereas the typical group-type assignment for diesel is also met.     

大豆油脂肪酸甲酯化条件的研究

氢氧化钾-甲醇甲酯化是用气相色谱法测定植物油脂肪酸组成的常用衍生方法。本文采用单因素试验及正交试验,以大豆油中亚油酸为主要考核目标,同时,观察其他主要脂肪酸含量变化,研究氢氧化钾-甲醇法甲酯化的优化条件。