On the application of the Dumas technique for the determination of nitrogen in refractory nitrides

Lengauer, W.

doi:10.1016/0039-9140(91)80152-p

Cited by 11 publications

(3 citation statements)

References 10 publications

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“…The concentrations of carbon and nitrogen in the litter samples were determined using an element analyzer (Elementar Analysensysteme GmbH, Hanau, Germany) [40]. The instrument's fundamental principle is the Dumas combustion equilibrium theory [41]. A prepared sample of 0.1 g litter was weighed, wrapped in a tin capsule, and fed via the autosampler into the combustion reaction tube, and a small quantity of pure oxygen was introduced into the system to help in the complete burning of the sample.…”

Section: Sampling and Chemical Analysesmentioning

confidence: 99%

Abnormal Litter Induced by Typhoon Disturbances Had Higher Rates of Mass Loss and Carbon Release than Physiological Litter in Coastal Subtropical Urban Forest Ecosystems

Wang

et al. 2022

Forests

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The decomposition of abnormal litter caused by extreme weather events might play an increasingly important role in carbon and nutrient cycling in forest ecosystems under climate change scenarios, which needs to be fully investigated. In August 2020, the abnormal foliar litter of the goldenrain tree (Koelreuteria bipinnata var. Integrifoliola), the camphor tree (Cinnamomum camphora), and the weeping willow (Salix babylonica) after Typhoon Hagupit disturbance were collected and incubated on the soil surface at the Plant Ecology Research Base at Taizhou University, which is located on the eastern coast of China. Simultaneously, the physiological foliar litter of these three trees collected in the spring litter peak was incubated at the same site. The abnormal litter had higher concentrations of carbon (C), nitrogen (N), and phosphorus (P) and lower concentrations of lignin and cellulose than the physiological litter. The accumulative mass loss rates of abnormal litter in the goldenrain tree, the camphor tree, and the weeping willow during the incubation period increased by 7.72%, 29.78%, and 21.76% in comparison with physiological litter, and the corresponding carbon release increased by 9.10%, 24.15% and 19.55%, respectively. The autumn litter peak period and plum-rain season had higher rates of litter mass loss and carbon release, while the winter nongrowing season had lower rates. Accumulative mass loss, accumulative carbon release, daily mass loss and the daily carbon release of foliar litter were significantly and positively correlated with temperature and initial P concentrations, and significantly and negatively correlated with the initial C/P ratio, lignin/N ratio, and lignin/P ratio (p < 0.05). Compared with the physiological litter, abnormal litter had higher initial substrate quality, which may be the most important factor contributing to their high rates of mass loss and carbon release. The results imply that increasing tropical cyclones under climate change scenarios will facilitate carbon cycling in coastal urban forest ecosystems.

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Section: Sampling and Chemical Analysesmentioning

confidence: 99%

Abnormal Litter Induced by Typhoon Disturbances Had Higher Rates of Mass Loss and Carbon Release than Physiological Litter in Coastal Subtropical Urban Forest Ecosystems

Wang

et al. 2022

Forests

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“…However, these techniques require reference materials themselves. Also techniques like Dumas analysis (volumetric analysis or gaschromatography [9][10][11] of nitrogen) and combustion analysis together with conductivity measurements (absorption of CO 2 in NaOH) for carbon are employed. The calibration of these techniques is either not necessary or is conducted by compounds with a well-established composition such as pure carbon black or an organic compound.…”

Section: Choice Of Phases and Measurement Of The Gross Chemical Compo...mentioning

confidence: 99%

Thermochemical Basis of the Preparation of Well-Defined Transition Metal Carbide, Nitride and Carbonitride Reference Materials for Electron-Probe Microanalysis (EPMA)

Lengauer

Bohn

2018

SSP

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A common and straightforward method for the standardisation in electron-probe microanalysis (EPMA) is the use of homogeneous reference materials prepared by various techniques such as by melting, sintering, high-temperature annealing and hot-pressing. The reference materials have to be analysed by independent methods accurately in order to define their “true” composition. For some compounds the preparation techniques are difficult because of their specific thermo-chemical properties (e.g. low diffusivities, high equilibrium nitrogen pressure, incongruent melting). In addition, many compounds show large homogeneity ranges with an a priori existing uncertainty in composition, contrary to what is generally preferred: to use compounds with a narrow homogeneity range (“line compounds”). For the latter, diffusional preparation techniques can be applied to yield diffusion layers instead of massive samples for standardisation. However, also single-phase samples with narrow homogeneity ranges can be prepared by diffusion, depending on the phase equilibria in the corresponding system. The presentation summarises efforts that have been made in order to prepare various reference materials for carbon and nitrogen standardisation of EPMA by various techniques. The boundary conditions such as phase stabilities, phase compositions and diffusion kinetics, which are important for their preparation to obtain well-defined reference samples are discussed. These samples were applied to various WDS/EPMA-based studies of phase diagrams and diffusion kinetics by means of Cameca SX 50 and SX 100 microprobes.

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“…Melamineissometimesillegallyaddedtofoodproductsinordertoincreasetheapparentproteincontent.Standardtest,such astheKjeldahlandDumastests,estimateproteinlevelsbymeasuringthenitrogencontent [9][10][11] ,sotheycanbemisledbyadding nitrogen鄄richcompoundssuchasmelamine.InSeptember2008, severalcompanieswereimplicatedinascandalinvolvingmilk infantformulawhichhadbeenadulteratedwithmelamine,leadingtokidneystonesandotherrenalfailure,especiallyamong youngchildren.…”

Section: Vol25mentioning

confidence: 99%

Enthalpy of Formation, Heat Capacity and Entropy of Melamine

Liu

Xiong²,

Shan-Zhou³

et al. 2009

Acta Physico-Chimica Sinica

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驻 c H 苓 m = (-2455.17依4.65)kJ•mol-1 ; 驻 f H 苓 m =(-763.38依5.16)kJ•mol-1 .ThebondenthalpyofC抑 N(betweensinglebondand doublebond)inmelaminewasthenestimatedtobe458.30kJ•mol-1 accordingtotheralationshipbetweenbond enthalpyandcombustionenthalpy.ThisvalueislargerthanthatofC-NbutsmallerthanthatofC襒N.Heatcapacity measurementswerecarriedoutinasmallsampleadiabaticcalorimeterfrom80to385K.Weobtained 驻 f H 苓 m at differenttemperaturesbetween80and385Kusingtheheatcapacitydata.Throughcalculationwiththevaluesofheat capacity,therelationshipbetweenthestandardmolarenthalpyofformationandtemperatureisalsopresentedasa functionalequation.Wealsomeasuredthethermolstabilityofmelaminebythethermogravimetry鄄differentialscanning calorimetry(TG鄄DSC)technique,whichshowedathermaldecompositionpeakat603.37KfortheDSCcurve.

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On the application of the Dumas technique for the determination of nitrogen in refractory nitrides

Cited by 11 publications

References 10 publications

Abnormal Litter Induced by Typhoon Disturbances Had Higher Rates of Mass Loss and Carbon Release than Physiological Litter in Coastal Subtropical Urban Forest Ecosystems

Abnormal Litter Induced by Typhoon Disturbances Had Higher Rates of Mass Loss and Carbon Release than Physiological Litter in Coastal Subtropical Urban Forest Ecosystems

Thermochemical Basis of the Preparation of Well-Defined Transition Metal Carbide, Nitride and Carbonitride Reference Materials for Electron-Probe Microanalysis (EPMA)

Enthalpy of Formation, Heat Capacity and Entropy of Melamine

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