Thermogravimetric analysis of wheatleyite Na<Subscript>2</Subscript>Cu<Superscript>2+</Superscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>·2H<Subscript>2</Subscript>O

Evidence for the existence of primitive life forms such as lichens and fungi can be based upon the formation of oxalates. These oxalates form as a film like deposit on rocks and other host matrices. The anhydrous oxalate mineral moolooite CuC₂O₄ as the natural copper(II) oxalate mineral is a classic example. Another example of a natural oxalate is the mineral wheatleyite Na₂Cu²⁺(C₂O₄)₂·2H₂O. High resolution thermogravimetry coupled to evolved gas mass spectrometry shows decomposition of wheatleyite at 255°C. Two higher temperature mass losses are observed at 324 and 349°C. Higher temperature mass losses are observed at 819, 833 and 857°C. These mass losses as confirmed by mass spectrometry are attributed to the decomposition of tennerite CuO. In comparison the thermal decomposition of moolooite takes place at 260°C. Evolved gas mass spectrometry for moolooite shows the gas lost at this temperature is carbon dioxide. No water evolution was observed, thus indicating the moolooite is the anhydrous copper(II) oxalate as compared to the synthetic compound which is the dihydrate.     

Thermal decomposition of humboldtine: A high resolution thermogravimetric and hot stage Raman spectroscopic study

Evidence for the existence of primitive life forms such as lichens and fungi can be based upon the formation of oxalates. These oxalates form as a film like deposit on rocks and other host matrices. Humboldtine as the natural iron(II) oxalate mineral is a classic example. Thermogravimetry coupled to evolved gas mass spectrometry shows dehydration takes place in two steps at 130 and 141°C. Loss of the oxalate as carbon dioxide occurs at 312 and 332°C. Dehydration is readily followed by Raman microscopy in combination with a thermal stage and is observed by the loss of intensity of the OH stretching vibration at 3318 cm^-1. The application of infrared emission spectroscopy supports the results of the TG-MS. Three Raman bands are observed at 1470, 1465 and 1432 cm^-1 attributed the CO symmetric stretching mode. The observation of the three bands supports the concept of multiple iron(II) oxalate phases. The significance of this work rests with the ability of Raman spectroscopy to identify iron(II) oxalate which often occurs as a film on a host rock.This revised version was published online in November 2005 with corrections to the Cover Date.     

Thermogravimetric study of polyacrylamide with evolved gas analysis

Dried samples of polyacrylamide in an He atmosphere have been subjected to thermogravimetric analysis in the 30–600°C range, and the evolved gases were monitored by FTIR. Water, ammonia, and small quantities of carbon dioxide are released in the first stages of decomposition (220–340°C), where the polymer chains remain intact and the reaction occurs on the pendant amide groups. In the second stage of decomposition (340–440°C), the majority of the weight loss occurs, and main chain breakdown occurs, releasing carbon dioxide, water, nitrile compounds, and imides. Trapping of the gases in this stage and analysis by GC–FTIR and GC–MS reveals the presence of more than 20 decomposition products, and confirms that a large proportion of these can be assigned to glutarimide and its substituted analogs. Imidization and dehydration reactions on the amide groups, as well as free radical breakdown of the main chains, with inter- and intramolecular hydrogen transfer, can account for many of the products of the decomposition. © 1993 John Wiley & Sons, Inc.     

Thermal decomposition of copper(II) and zinc carbonate hydroxides by means of TG-MS

Summary For the quantitative analyses of evolved CO₂and H₂O during the thermal decomposition of solids, calibration curves, i.e. the amounts of evolved gases vs. the corresponding peak areas of mass chromatograms measured by TG-MS, were plotted as referenced by the reaction stoichiometry of the thermal decomposition of sodium hydrogencarbonate NaHCO₃. The accuracy and reliability of the quantitative analyses of the evolved CO₂and H₂O based on the calibration curves were evaluated by applying the calibration curves to the mass chromatograms for the thermal decompositions of copper(II) and zinc carbonate hydroxides. It was indicated from the observed ratio of evolved CO₂and H₂O that the compositions of copper(II) and zinc carbonate hydroxides examined in this study correspond to mineral malachite, Cu₂CO₃(OH)₂, and hydrozincate, Zn₅(CO₃)₂(OH)₆, respectively. Reliability of the present analytical procedure was confirmed by the fairly good agreement of the mass fraction of the evolved gases calculated from the analytical values with the total mass-loss during the thermal decompositions measured by TG.     

EGA/MS Investigations on the Thermal Degradation of Diammoniumhexachloroplatinate

The thermal degradation of diammoniumhexachloroplatinate (NH₄)₂PtCl₆ is used in technical scale for the production of the pure platinum metal [1] and for this reason of great interest. Our investigations have been focused on the influence of the different atmospheres (oxidizing, inert or reducing) used in the technical processes towards the degradation mechanism and the evolved volatile degradation products. The second main aspect of our investigations was the evolution of volatile platinum species. Regarding the different frequencies of platinum allergies related to the different technical processes, the evolution of volatile platinum species is of great importance, due to the supposed allergic potential of this substances [2–4]. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal degradation of organo-soluble polyimides

The thermal degradation behavior of two organo-soluble polyimides was investigated by high resolution pyrolysis-gas chromatography/mass spectrometry. The pyrolyzates of the polymers at various temperatures were identified and characterized quantitatively. The relationship between the polymer structure and pyrolyzate distribution was discussed. The kinetic parameters of the thermal degradation were calculated based on thermogravimetric measurements. Finally, the thermal degradation mechanism for the polymers was suggested.     

Thermal decomposition of transition metal carboxylates

Dynamics of changes in microstresses during thermal decomposition of Cu(HCOO)₂ crystals and their effect on the thermal decomposition kinetics were studied by IR spectroscopy at 105 to 120 °C. The formation of solid intermediate HCOOCu was observed, and the dynamics of its accumulation was followed. Kinetic regularities of transformation of HCOO groups were compared with those for gas evolution.For Communication 1, see Ref. 1.Translated from Izvestiya va Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 350–354, February, 1996.     

On the Thermal Decompositions of the Trivalent Trioxalato Complexes of Al, Cr, Mn, Fe and Co

The thermal decompositions of the complexes K₃[M(ox)₃]3H₂O(M=Al, Cr, Mn, Fe, Co; ox=C₂O₄^2–) were studied. Dehydration of the complexes occurs up to 200°C, this being a three-step process for M=Al, Cr, Mn and Co, and a two-step process for M=Fe. Decomposition of the dehydrated complexes proceeds in several steps. For M=Al, Cr and Fe, the decomposition takes place with the evolution of CO, whereas for M=Mn and Co the decomposition of the oxalate ligand yields solid C besides CO. The temperature of CO liberation decreases in the series Cr<Al<Co<Mn<Fe. For M=transition metal, this trend can be explained by the fact that the strength of the C—C bond in the oxalate ligand decreases in the series Cr<Co<Mn<Fe.This revised version was published online in November 2005 with corrections to the Cover Date.     

生物样品二恶英分析中两个常见干扰峰的鉴定

利用高分辨气相色谱/高分辨质谱联用仪（HRGC/HRMS）和高分辨气相色谱/低分辨质谱仪（HRGC/LRMS）对实际生物样品中二恶英（polychlorinated dibenzo-p-dioxins and dibenzofurans,PCDD/Fs）的分析过程中¹³C标记的2,3,7,8-四氯代二苯并呋喃（¹³C₁₂-2,3,7,8-TCDF）监测碎片离子通道的两个常见干扰峰进行了分析鉴定。通过实际样品分析结果首先推测这两个干扰峰可能为有机氯农药类化合物滴滴涕（DDT）降解产物滴滴伊（DDE）的两个异构体,其次采用DDE的标准溶液（包括o,p’-DDE和p,p’-DDE）进行分析确认。通过HRGC/HRMS的色谱峰分离效果分析、色谱保留时间匹配以及与DDE碎片离子的理论丰度比进行比较,最终确认实际样品分析中的两个干扰峰依次为o,p’-DDE和p,p’-DDE。本文可为生物样品中二恶英的准确识别提供重要参考。     

热分析与气相色谱联用研究一水合草酸氢钾

用热分析与气相色谱联用技术(TA-GC)研究KHC₂O₄·H₂O的热分解表明,在空气和氦气当中,开始时缓慢分解,放出结晶水。接着KHC₂O₄快速分解成K₂C₂O₄,并释放出一些气体产物：O₂(分解初期)、CO、CO₂和H₂O。讨论了KHC₂O₄的分解机理。     

Thermal Studies of Copper(II) Squarate Complexes of Diamines in the Solid State

CuL₂C₄O₄ [L=ethane-1,2-diamine (en)], CuL₂C₄O₄⋅2H₂O [L=N-methylethane-1,2-diamine (meen), N-ethylethane-1,2-diamine (eten),N-propylethane-1,2-diamine (pren), N-methyl-N’-ethylethane- 1,2-diamine (meeten) andpropane-1,2-diamine (pn)], CuL₂C₄O₄⋅0.5H₂O [L=N,N’-dimethylethane- 1,2-diamine (dmeen)], CuL₂C₄O₄⋅4H₂O [L=propane-1,2-diamine (pn)]and CuL₂C₄O₄⋅H₂O[L=2-methylpropane-1,2-diamine (ibn)] have been synthesized by the addition of respective diamine to finely powdered CuC₄O₄⋅2H₂O and their thermal studies have been carried out in the solid state. Cu(en)₂C₄O₄ upon heating loses one molecule of diamine with shar pcolour change yielding Cu(en)C₄O₄ which upon further heating transforms to unidentified products. All aquated-bis-diamine species [CuL₂C₄O₄⋅2H₂O, CuL₂C₄O₄⋅0.5H₂O and CuL₂C₄O₄⋅H₂O] upon heating undergo deaquation–anation reaction in the solid state showing thermochromism and transform to CuL₂C⁴O₄, which revert on exposure to humid atmosphere (RH ∼90%). All the squarato bis-diamine species, CuL₂C₄O₄, on further heating transform to unidentified products through the formation of CuLC₄O₄ as intermediates. The mono diamine species, have been isolated pyrolytically in the solid state and can be stored in a desiccator as well as in open atmosphere. They are proposed to be polymeric. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal decomposition of jarosites of potassium,sodium and lead

Summary Jarosites are a group of minerals formed in evaporite deposits and form a component of efflorescence. As such the minerals can function as cation and heavy metal collectors. Thermogravimetry coupled to mass spectrometry has been used to study three Australian jarosites which are predominantly K, Na and Pb jarosites. Mass loss steps of K-jarosite occur over the 130 to 330 and 500 to 622°C temperature range and are attributed to dehydroxylation and desulphation. In contrast the behaviour of the thermal decomposition of Na-jarosite shows three mass loss steps at 215 to 230, 316 to 352 and 555 to 595°C. The first mass loss step for Na-jarosite is attributed to deprotonation. For Pb-jarosite two mass loss steps associated with dehydroxylation are observed at 390 and 418°C and a third mass loss step at 531°C is attributed to the loss of SO₃. Thermal analysis is an excellent technique for the study of jarosites. The analysis depends heavily on the actual composition of the jarosite.     

Thermal decomposition of struvite

Struvite (NH₄MgPO₄·6H₂O) is a mineral often found in urinary tracts and kidneys. Thermal decomposition using slow low heating shows that the 'kidney' stone can be decomposed at temperatures below 40°C. At this temperature both ammonia and water are evolved. If more rapid heating is employed the decomposition occurs at around 80°C. The implication of this work rests with the use of low slow heat for the decomposition of the kidney stones. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal,structural and optical properties of Al2CoO4-Crocoite composite nanoparticles used as pigments

Novel zinc(II) complex compounds of general formula Zn(C₆H₅COO)₂·L₂ (where L=caffeine (caf) and urea (u)) were synthesized and characterized by elemental analysis and IR spectroscopy. The thermal behaviour of the complexes was studied during heating in air by thermogravimetry. It was found that the thermal decomposition of the anhydrous Zn(II) benzoate compounds with bioactive ligands was initiated by the release of organic ligands at various temperatures. On further heating of the compounds up to 400°C the thermal degradation of the benzoate anions took place. Zinc oxide was found as the final product of the thermal decomposition of all zinc(II) benzoate complex compounds heated to 600°C. Results of elemental analysis, infrared spectroscopy, mass spectroscopy and thermogravimetry are presented.     

Thermal Investigation of the Compounds of the Copper(II) Mono(o-hydroxybenzoate) with Chelate Ligands

Heteroligand complexes of copper(II) were obtained as a result of the reaction of Cu(II) mono (o-hydroxybenzoate) (monohydrate) with 8-hydroxyquinoline (HOx), o-aminophenol (NH₂Ph) and 2,2′-dipyridyl (2,2′-dipy). The mixture of the mono compound with: Cu(II) di(o-aminobenzoate) or Cu(II) di(o-hydroxybenzaldoximate) were obtained by the reaction with o-aminobenzoic acid (H₂A) and o-hydroxybenzaldoxime (H₂Salox). The obtained compounds and their sinters were subjected to chemical, X-ray and thermal analyses. This revised version was published online in July 2006 with corrections to the Cover Date.     

同位素稀释高分辨气相色谱-高分辨质谱法测定土壤中痕量有机氯农药残留

建立了同位素稀释高分辨气相色谱-高分辨质谱测定土壤中痕量有机氯农药残留的分析方法。采用加速溶剂法萃取土壤样品,以正己烷/丙酮(体积比为1:1)为提取溶剂,提取液经过Florisil硅土固相萃取小柱净化后,采用高分辨DB-5MS毛细管色谱柱(30 m×0.25 mm×0.25 μm)分离,以保留时间和同位素特征离子丰度比定性,同位素峰面积比定量。实验结果表明,方法的回收率为77.3%～114.5%,相对标准偏差(RSD)≤10.81%（n=5）,检出限均小于0.04 pg/g。应用该方法检测某地区表层土壤中的有机氯农药,结果表明该方法适合测定环境土壤背景中痕量有机氯残留。     

Preparation and Thermal Decomposition of Copper(II) Complexes with 4-Methylimidazole

Simple and mixed compounds of the formulae Cu(4-Meim)₂, CuSal(4-Meim), CuSal(4-Meim)₂ and CuSalox(4-Meim)₂, where 4-Meim=4-methylimidazole, Sal=(OC₆H₄COO)²⁻, Salox=(OC₆H₄CHNO)²⁻ have been prepared. Thermal decomposition reactions have been established on the basis of thermal and X-ray analyses of these compounds. The pyrolysis proceeds in several (3–4) stages connected with the mass loss and exothermic effects. As a result of the last stage of decomposition CuO is formed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Characterisation and thermal analysis of vanadium(II) oxalate

The synthesis, compositional formula and mode of thermal decomposition of a compound for which there existed only a single literature reference [1] have been investigated in this work.The product of the aqueous phase reaction between vanadium(II) ions and oxalate ions at lowpH has been identified: vanadium(II) oxalate dihydrate, VC₂O₄·2H₂O, has been characterised by thermal methods of analysis supported by a range of complementary analytical techniques.The findings of a previous author [1] have been confirmed and extended in this work. In addition, a synthetic procedure for the preparation of gram quantities of vanadium(II) oxalate dihydrate, VC₂O₄·2H₂O, is reported here for the first time.The oxalate compound prepared was found to be remarkably stable in relation to aerial oxidation, unlike other representative solid state compounds of the vanadium(II) oxidation state. Vanadium(II) oxalate dihydrate may, therefore, serve as an important intermediate in the future synthesis of other vanadium(II) compounds.We would wish to thank Mr. S. Sutcliffe, University College Salford, for providing the Thermal Analysis data and also Mr. S. Unsworth, Magnesium Electron, Clifton, Manchester, for providing the XRD data.     

Thermal Behaviour of Metal Complexes of 6-(2-Pyridylazo)-3-acetamidophenol

The present work aims chiefly to study the thermal behaviour of complex compounds with general formula: [M(HL)xH₂O](A)yH₂O (where HL=C₁₃H₁₁N₄O₂=6-(2-pyridylazo)-3-acetamidophenol (PAAP), M=Cu(II), Zn(II), Cd(II) and Fe(III) x=1, 3; y=2, 5) while A=CH₃COO^– (Ac), Cl₂. The second formula is [M(H₂L)xH₂O]Cl₂yH₂O, (where H ₂ L=C₁₃H₁₂N₄O₂ (PAAP), M=Ni(II), Co(II) x=3; y=4, 6). The compounds were identified by elemental analysis, FT-IR spectra and TG/DTG,DTA methods. It was found that during the thermal decomposition of complex compounds water molecules of crystallization are released in the first step. In the next step the pyrolysis of organic ligand takes place. Metal oxide remained as a solid product of the thermal decomposition. Mass spectroscopy has been used for the determination of the thermal decomposition on the intermediate products. It was found that the thermal stability of the studied compounds increases as the ionic radii decreases. The activation energy E, the entropy change S ^*, the enthalpy H ^* change and Gibbs free energy change G ^* were calculated from TG curve.This revised version was published online in November 2005 with corrections to the Cover Date.     

高分辨气相色谱-高分辨质谱测定活性污泥中的多溴联苯醚

建立了利用高分辨气相色谱-高分辨质谱定量测定多溴联苯醚(PBDEs)的方法,参与了测定PBDEs的国际比对实验,实验结果表明该法是可行的。对不同地区（北京、山东临沂、上海）的3个污水处理厂的活性污泥进行了索氏提取、多层复合硅胶柱分离,然后用所建立的方法测定了19种多溴联苯醚单体的含量。结果表明,北京某污水处理厂的活性污泥中PBDEs的总量高于其他两者。