对科学方法和科学方法教育的再认识——祝贺《化学教育》30周年刊庆

科学方法是科学活动经验升华、程序化、规范化、强化的结果,是科学活动的过程规定性工具。方法的思维是科学方法的精髓。对具体的科学方法进行概括,形成科学方法的适用范围不同的层次。科学方法大体上可以分为经验方法、理性方法和具有补充、完善意义的"第三类方法"以及综合性方法。科学方法有局限性,需要关注方法的改进,注意创新。要搞好科学方法教育,必须以科学方法形成和发展的规律为基础,既要考虑科学方法的特点,也要考虑教育对象的特点。     

光电直读光谱法测定铝及铝合金中硅含量时的方法验证北大核心CSCD

基于原子发射光谱技术的光电直读光谱法主要用于金属材料的理化分析,具有制样简单、操作简便、分析快速、准确度高、可多元素同时检测等优点,在金属行业中应用广泛。实验室在开展检测工作前,必须对使用的标准方法进行方法验证,对于非标准方法、实验室制定的方法、超出预定测量范围使用的标准方法或其他扩充和修改过的标准方法进行全面的方法确认。方法验证不仅要识别标准方法的规定要求,还要通过试验证明测定结果的准确度和可靠性,这是对实验室检测能力的重要评价。     

水体中铊的富集分离方法的研究进展

综述了近20年来。水体中铊的富集分离方法,如物理方法、化学方法、生物方法和电化学方法的研究现状,讨论了不同方法的优缺点,展望了水体中铊富集分离方法的发展方向(引用文献42篇)。     

物理化学中的热力学方法、拓展及应用

主要依托物理化学中的热力学基本原理,浅议热力学方法、简介化工热力学方法和工程热力学方法及应用等。热力学方法主要有循环法、特性函数法、变量变换法、标准状态法、平衡法及极值法、微元法等,并归纳了各种方法的特点、作用及意义。对于学生学习物理化学中的热力学,具有一定的指导意义,拓展了热力学的基本知识。     

电感耦合等离子体原子发射光谱测定铬矿中的铅、锌、镍、钛、磷

提出了电感耦合等离子体原子原子发射光谱测定铬矿中的铅、锌、镍、钛、磷含量的方法,选择各元素的分析谱线,采用正交试验的方法确定仪器的工作参数,方法的检出限0.22 ~1.50ug·L-1 ,方法的回收率在89%~112%,测定值的相对标准偏差（n=5）小于1.45%,方法用于铬矿杂元素的分析结果与现有的国标检验方法测定值一致。填补无铬矿中铅、锌、钛元素检测方法的空白。     

新课程下化学教学中学法指导方法的研究

当前,学法指导是一个薄弱环节。指导学生提高记忆效果的方法、善于提出问题的方法、掌握听好课的方法、以及掌握解题技巧的方法,是学法指导研究的重要内容。     

自由基检测技术进展

重点对主要的几种自由基检测技术的发展情况进行了讨论,并评价了各种方法的优缺点。涉及的自由基检测技术主要有分光光度吸收法与荧光方法、高效液相色谱法、化学发光法、电化学方法、自旋捕集技术和毛细管电泳方法,按间接检测方法和直接检测方法分类进行了评价。     

论化学方法的职能

化学方法是指从事化学研究的基本手段和思维工具;它既有自然科学研究一般方法的共性,又具有化学研究特殊方法的个性。化学方法有多种,主要有化学选题、化学符号语言规范、化学实验、化学假说、化学模型、化学数学和化学逻辑等。在诸种化学方法中,化学     

对微孔吸附常用经典分析模型的比较

文章采用列表对比的方式,简要介绍了微孔吸附常用经典模型的出处、应用范围、发展历史和各自的特点。为了方便系统了解和掌握物理吸附中的微孔经典分析方法,文章将其分成三类：(1)由标准等温线发展出的方法,包括t-图法、αs-图法、n-图法和MP法;(2)基于微孔填充理论的方法,包括D-R方法、D-A方法和D-R-S方法;(3)目前普遍使用的方法,包括原始HK方法(狭缝型孔)、HK-SF方法(圆柱型孔)和HK-CY方法(球型孔)以及三种改进后的HK方法。     

中学化学中的科学方法教育与课程教材改革

本文论述了什么是科学方法;科学方法的特点、性质、类型和结构;为什么要重视科学方法教育;中学化学中应该着重进行哪些科学方法教育;怎样才能有效地进行科学方法教育等问题。指出:科学方法是科学素质的重要构成因素。加强科学方法教育是全面提高学生素质、保证学生可持续发展的需要,也是搞好当前的课程教材改革的需要。文中提出了确定中学化学中科学方法教学内容的原则、各年级教学内容和教学要求的设想,还就科学方法教育的途径和原则提出了自己的看法。作者认为,科学方法教育要力戒教条式灌输,要注意让学生在积累经验基础上进行归纳;重视组织学生参加有关的实践活动;科学方法教育要跟科学精神、科学思想和科学知识的教育相互结合,跟人文精神教育结合。在进行科学方法教育时,还应该重视技术方法教育。     

Determination of residual oil in diesel oil by spectrofluorimetric and chemometric analysis

Multivariate calibration (PLS), principal components analysis (PCA) and linear discriminant analysis (LDA), associated to synchronous spectrofluorimetry, were used to identify and quantify non-transesterified residual vegetable oil in diesel oil with the addition of 2% of biodiesel (B2). The addition of residual oil, one of the easiest ways of adultering fuel, damages engines and leads to tax evasion. Using this method, the samples of diesel oil, B2, and B2 contaminated with residual oil were classified correctly and separated into three well-defined groups. The quantification of residual oil in B2 was carried out in the 0-25% (w/w) band, RMSEC and RMSEP values ranging from 0.26 to 0.48% (w/w) and 1.6-2.6% (w/w), respectively. The method is highly sensitive and efficient to identify and quantify this type of adulterant in which 100% of the samples were correctly classified and the average relative error was approximately 4% in the range 0.5-25% (w/w).     

Detection of hazelnut oil in virgin olive oil by assessment of free sterols and triacylglycerols

Free sterols were evaluated as factors for discriminating between genuine virgin olive oil and hazelnut-mixed virgin olive oil. Numeric analyses of the results amplified the differences between groups. The application of this method to virgin olive oil samples and their mixtures with 10% hazelnut oil distinguished between genuine and nongenuine virgin olive oil with statistical certainty. Triacylglycerol analysis was tested for the same purpose by using parameter deltaECN42, but although it possessed a discriminating capacity, it alone could not distinguish the aforementioned groups with sufficient certainty. Free delta7-sterols data were combined with deltaECN42 data into a single discriminating function to improve differentiation and bring more ruggedness, and for detection of low amounts (10%) of hazelnut oil in virgin olive oil. In fact, the values obtained by addition of delta7-sterol data and deltaECN42 data showed a higher discriminating capacity than single parameters. In a single operation the method produced all the oil fractions necessary for analysis of free sterols and triacylglycerols with ECN42. Solid-phase extraction was applied in substitution of traditional chromatography on a silica column.     

顶空气相色谱-质谱测定橄榄调和油中橄榄油含量

建立了测定橄榄调和油中橄榄油含量的顶空气相色谱-质谱分析方法。对样品量、加热温度、加热时间、进样量、进样模式、色谱柱进行了优化。通过化学计量学方法发现了橄榄油的特征化合物。取1.0 g样品放置于20 m L顶空瓶中,在180℃加热振摇2 700 s,取1.0 m L顶空气体进样,通过HP-88色谱柱分离和质谱检测。结果表明,方法的线性范围为0~100%(橄榄油含量),线性相关系数(r2)大于0.995,检出限为1.26%~2.13%,模拟橄榄调和油中橄榄油含量测定的偏差为-0.65%~1.02%,相对偏差为-1.3%~6.8%,相对标准偏差为1.18%~4.26%(n=6)。该方法不使用任何溶剂,操作简单、快速、环保,灵敏度和准确度高,适用于橄榄调和油中橄榄油含量的测定。     

Direct olive oil authentication: detection of adulteration of olive oil with hazelnut oil by direct coupling of headspace and mass spectrometry, and multivariate regression techniques

Control of adulteration of olive oil, together with authentication and contamination, is one of the main aspects in the quality control of olive oil. Adulteration with hazelnut oil is one of the most difficult to detect due to the similar composition of hazelnut and olive oils; both virgin olive oil and olive oil are subjected to that kind of adulteration. The main objective of this work was to develop an analytical method able to detect adulteration of virgin olive oils and olive oils with hazelnut oil by means of its analysis by a headspace autosampler directly coupled to a mass spectrometer used as detector (ChemSensor). As no chromatographic separation of the individual components of the samples exists, a global signal of the sample is obtained and employed for its characterization by means of chemometric techniques. Four different crude hazelnut oils from Turkey were employed for the development of the method. Multivariate regression techniques (partial least squares and principal components analysis) were applied to generate adequate regression models. Good values were obtained in both techniques for the parameters employed (standard errors of prediction (SEP) and prediction residual error sum of squares (PRESS)) to evaluate its goodness. With the proposed method, minimum adulteration levels of 7 and 15% can be detected in refined and virgin olive oils, respectively. Once validated, the method was applied to the detection of such adulteration in commercial olive oil and virgin olive oil samples.     

颗粒粒径对油页岩热解产油率的影响

以桦甸油页岩为原料研究了颗粒粒径对油页岩热解产油率的影响。将油页岩破碎、筛分得到<0.074、0.074~0.125、0.125~0.25、0.25~0.5、0.5~1和1~3 mm不同粒级样品,再将0.25~0.5、0.5~1和1~3 mm大粒级样品粉碎制得对应的细粉样品,采用低温干馏法和热重分析分别测定表征样品的油产率和有机质含量。结果表明,油产率随着粒径减小逐渐降低,从1~3 mm下的11.92%降到<0.074 mm下的6.14%。热重分析表明,有机质含量随着粒径降低而降低,且油产率与有机质含量有明显的线性关系。0.25~0.5、0.5~1和1~3 mm样品经粉碎后油产率降低、气产率升高,但变化值均小于1%。在破碎过程中有机质选择性地富集在大粒级样品中,且页岩油二次反应程度随着粒径的减小而增大,使得页岩油产率随着粒径的降低而降低,且有机质选择性富集是主导因素。     

Characterization of essential oil components of Iranian geranium oil using gas chromatography-mass spectrometry combined with chemometric resolution techniques

The essential oil components of geranium oil cultivated in center of Iran were identified and determined using gas chromatography-mass spectrometry data combined with the chemometric resolution techniques. A total of 61 components accounting for 91.51% were identified using similarity searches between the mass spectra and MS database. This number was extended to 85 components using chemometric techniques. Various chemometric methods such as morphological scores, simplified Borgen method (SBM) and fixed size moving window evolving factor analysis (FSMWEFA) were used for determining the number of components, pure variables, zero concentration and selective regions. Then the overlapping peak clusters were resolved into pure chromatograms and pure mass spectra using heuristic evolving latent projections (HELP) method. A characteristic feature of the Iranian geranium oil is the absence of 10-epi-gamma-eudesmol in its constituents compared with the oil from northern and southern parts of India. The results of this work show that combination of hyphenated chromatographic methods and resolution techniques provide a complementary method for accurate analysis of essential oils.     

Analysis of oil used in late Roman oil lamps with different mass spectrometric techniques revealed the presence of predominantly olive oil together with traces of animal fat.

The lipid fraction of residues in ancient oil lamps found at the archaeological site of Sagalassos (south-west Turkey) was analysed by gas chromatography (GC) coupled to mass spectrometry (MS). The identification of plant sterols and long chain alcohols suggested that a vegetable oil was used in these lamps. The lipid sample was also analysed with reversed-phase liquid chromatography (LC) coupled to MS with atmospheric pressure chemical ionization (APCI). The identification of TAG's detected with LC-APCI-MS showed that predominantly olive oil was used as a fuel for the antique oil lamps. The presence of large quantities of multiply unsaturated triacylglycerol (TAG) and traces of saturated TAG indicated that also other oils and animal fat were added. Summarizing, the analysis of TAG's with LC-APCI-MS in lipid extracts of ancient ceramics proved to be a valuable method to reconstitute the original contents.     

Study of degradation kinetics of sunflower oil on H-Beta zeolite

In this study, were studied the degradation of pure sunflower oil and mixed with H-Beta zeolite. This zeolite was synthesized by the hydrothermal method, followed by calcination and ion exchanged. The characterization of the zeolite was performed by X-ray diffraction and nitrogen adsorption/desorption by the method of BET. The analysis showed that H-Beta zeolite presented a good crystallinity and the template was completely removed from the catalyst. The thermal and catalytic degradation study was carried out using the TG/DTG method in multiple heating rates of 5, 10, and 20 °C min⁻¹. The isoconversion method proposed by Vyazovkin was applied to determine the kinetic parameters for degradation of the sunflower oil. The activation energy for the degradation process of pure sunflower oil was 193 kJ mol⁻¹, while for sunflower oil mixed with 20% of H-Beta zeolite was equivalent to 88 kJ mol⁻¹. It was verified that for the degradation of 90% of the sunflower oil mixed with H-Beta, for a period of 1 h, a temperature of 356 °C was required, whereas for the pure vegetable oil, this value was of 387 °C, at the same time period, showing that the catalyst was effective for the degradation process of sunflower oil.     

干酪根组成结构及其热解生油特性的红外光谱研究

对五种不同地区油页岩中干酪根进行了固体KBr压片红外吸收光谱分析,并通过曲线分峰拟合建立了干酪根中脂肪烃区域结构参数的定量测定方法。利用TG-FTIR联用分析技术对干酪根在20 ℃/min升温速率下热解挥发分析出组分在线定性分析,得到了脂肪烃结构参数随热裂解过程的反应特性及变化规律。研究表明,油页岩中干酪根由脂肪烃结构、芳香烃结构和含氧等官能团三部分组成。脂肪烃结构相对含量为18.5%~78.2%,并均以含长链亚甲基结构为主。随着演化程度的加深,干酪根中脂肪烃含量逐渐减少,生油能力也不断降低。干酪根热分解主要发生在350~520 ℃,520 ℃后热失重现象趋于平缓,在此温度下各样品残余半焦的质量分数为19.5%~52.2%。在线红外分析结果表明,干酪根热裂解过程中先析出游离水,随后发生解聚和脱水反应,主要的烷基侧链不断脱落、环化及含氧基团逐渐断裂生成各种烷烃类、羧酸类、醇类和醛类等物质,直至形成更加稳定的类石墨态结构。     

Thermooxidative decomposition of oil shales

The thermooxidative decomposition of four oil shale samples from Estonia, Jordan, Israel and Morocco and one sample of Estonian oil shale derivative, semicoke, was studied with the aim to determine the characteristics of the process and the differences of it related to the origin of oil shale. The experiments with a Setaram Setsys 1750 thermoanalyzer coupled to a Nicolet 380 FTIR Spectrometer were carried out under non-isothermal conditions up to 1000 °C at the heating rates of 1, 2, 5, 10 and 20 °C min⁻¹ in an oxidizing atmosphere. A model-free kinetic analysis approach based on the differential isoconversional method of Friedman was used to calculate the kinetic parameters. The results of TG–DTA–FTIR analyses and the variation of activation energy E along the reaction progress α indicated the complex character of thermooxidative decomposition of oil shale and semicoke, being at that the most complicated for Estonian and Jordanian oil shale characterized by higher content of organic matter as compared to the other samples studied.