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1.
快速准确测定土壤中铵态氮、硝态氮含量对监测土壤肥力水平和生态环境,指导作物氮肥施用非常重要。选择30份土样,利用全波长扫描式多功能读数仪(酶标仪)结合靛酚蓝分光光度法、硫酸肼还原法测定土壤中铵态氮和硝态氮含量,探讨利用酶标仪测定土壤无机氮含量的可行性。结果显示,利用酶标仪测定土壤铵态氮、硝态氮含量与连续流动分析仪测定结果之间无明显差异,彼此间呈显著线性相关。铵态氮回归直线方程为Y(连续流动分析仪-NH_4~+-N)=0.997 6 X(酶标仪-NH_4~+-N)-0.012 3,相关系数R=0.961 9(n=30,P0.01);硝态氮回归方程为Y(连续流动分析仪-NO_3~--N)=0.959 3 X(酶标仪-NO_3~--N)+0.021 9,相关系数R=0.964 0(n=30,P0.01)。酶标仪测定铵态氮回收率在96.2%~108%,相对标准偏差在10%以内;硝态氮测定回收率为94.9%~110%,且相对标准偏差在5%以内,酶标仪测定土壤铵态氮和硝态氮方法检出限分别为0.068mg/L和0.028mg/L。酶标仪测定土壤无机氮速度快,精密度、准确度较高,消耗试剂少,可用于大批量土壤浸提液中铵态氮和硝态氮含量的快速分析。 相似文献
2.
Arash Ghorbani‐Choghamarani Mohsen Nikoorazm Hamid Goudarziafshar Zahra Naserifar Parisa Zamani 《中国化学》2011,29(4):731-734
A mixture of ammonium nitrate or nitro urea and silica sulfuric acid was found to be efficient and environmentally friendly nitrating media for the preparation of orto‐nitro phenols in dichloromethane at room temperature. 相似文献
3.
K. Rossmanith 《Monatshefte für Chemie / Chemical Monthly》1994,125(10):1027-1031
Summary Lanthanum ammonium nitrate of purity 97%, containing 34.1 kgRE
2O3, was crystallized fractionally and yielded 32.5 kg oxide of purity better than 99.9% (the larger part was 99.99% pure). Out of mixtures with 66% Pr there resulted praseodymium ammonium nitrate containing 13.45 kg oxide of purity better than 99.5%. The effective separation factors are discussed, showing a better efficiency of the ammonium than of the magnesium double nitrates for the separation of praseodymium and lanthanum. 相似文献
4.
摘要:建立离子色谱法快速测定土壤中亚硝酸盐氮和硝酸盐氮的方法。土壤样品采用250 mL 0.01 moL/L 氯化钙溶液提取,于20℃水浴振荡60 min,静置离心。采用Ion Pac AS19离子色谱柱,以20 mmoL/L氢氧化钾溶液为淋洗液,流量为1.0 mL/min,进样体积为25 μL,以电导检测器进行检测。亚硝酸盐氮和硝酸盐氮的质量浓度在0.20~5.00 mg/L范围内与色谱峰面积呈良好的线性关系,线性相关系数均为0.9999,方法检出限分别为0.005,0.007 mg/L。样品的加标回收率为95.0%~97.4%,测定结果的相对标准偏差为0.89%~2.11%(n=12)。该方法适用于土壤中亚硝酸盐氮和硝酸盐氮含量的快速测定。 相似文献
5.
为了能够快速准确地掌握整个昆明地区土壤水解性氮含量的情况,收集963个不同类型的土壤样品,采用竞争自适应重加权采样(Competitiveadaptivereweightedsampling,CARS)变量选择方法筛选波长变量,并建立水解性氮的偏最小二乘法(Partialleastsquares,PLS)分析模型。结果表明,采用CARS方法优选波长变量后,模型参数有所改善,交互验证标准偏差(Rootmeansquareerrorofcrossvalidation,RMSECV)由31.63降至25.55,交互验证相关系数(Correlationcoefficientofcrossvalidation,Rcv)由078提升至0.84,且模型外部验证结果与内部交叉验证结果基本一致。研究结果表明近红外光谱技术结合CARS分法,在大量代表性样品建模下,能够有效建立昆明地区不同土壤类型的水解性氮含量的近红外数学模型,方法可推广应用于土壤其他组分的近红外检测,具有重要的指导意义。 相似文献
6.
Phase transitions of ammonium nitrate doped with alkali nitrates studied with fast X-ray diffraction
Dried samples of ammonium nitrate (AN) containing 1, 3, 5 mol% KNO3, RbNO3 and CsNO3 were investigated with temperature resolved X-ray diffraction. The samples were cycled with 2 temperature programs from –70° to 100° and –70° to 150°C, resp. DSC measurements were made for comparison.KNO3 extends the stability range of phase III. The supercooling observed with the transitions II/III and III/IV was so severe that the phases III and IV could be skipped leading to the transitions II/IV and III/V. No hindered nucleation was observed on heating.RbNO3 gives dried AN the properties of the humid nitrate. Phase III appeared on heating but was skipped on cooling, when the sample had been heated to 150°C. Hindered nucleation was observed.CsNO3 stabilizes the phases II and V. No strong hysteresis or supercooling was observed.
Zusammenfassung Trockene Ammoniumnitratproben (AN) mit einem Gehalt von 1, 3 bzw. 5 mol% KNO3, RbNO3 und CsNO3 wurden mittels Röntgendiffraktion in Abhängigkeit von der Temperatur untersucht. Die Proben durchliefen 2 Temperaturprogramme (von 70° auf 100° und von –70° auf 150°C). Zum Vergleich wurden DSC-Messungen durchgeführt.KNO3 erweitert den Stabilitätsbereich der Phase III. Die Unterkühlung bei den Übergängen II/III und III/IV war so ausgeprägt, daß man die Phasen III und IV überspringen konnte, um die direkten Phasenübergänge II/IV und III/V zu erhalten. Beim Erhitzen wurde keine behinderte Keimbildung beobachtet.RbNO3 verleiht trockenem AN die Eigenschaften von feuchtem Nitrat. Phase III tritt zwar beim Erhitzen auf, wird aber beim Abkühlen ausgelassen, wenn die Probe zuvor auf 150°C erhitzt wurde. Es wurde eine behinderte Keimbildung beobachtet.CsNO3 stabilisiert die Phasen II und V. Es wurde keine ausgeprägte Hysterese oder Unterkühlung beobachtet.相似文献
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8.
对氧化镁浸提-扩散法测定土壤中铵态氮的条件进行了研究,优化了氧化镁浸提-扩散温度和时间等实验条件,用振荡器代替人工转动扩散皿,最终确定较佳的氧化镁浸提-扩散温度为26℃,时间为15h。在优化条件下,方法的相对标准偏差(RSD,n=7)在1.1%~3.3%,NH4Cl的加标回收率在92.83%~103.1%,方法操作简单,测定结果准确可靠,精密度高,尤其适用于大批量样品的检测分析。 相似文献
9.
不同稀土改性SO42-/ZrO2催化剂的结构与性能表征 总被引:3,自引:0,他引:3
Solid superacid catalyst SO42-/ZrO2 was modified by different rare earth compounds and applied to the esterification of acetic acid and n-butanol. The effects of rare earth elements loading on the catalytic properties were studied and the correlation between the structure and properties was investigated by means of XRD, IR, UV, DTA and TG. The results show that the (NH4)2Ce(NO3)6 modification can enhance catalytic activity more and exhibit better stability than the other two compounds La(NO3)3 and Ce(NO3)3. Meanwhile,(NH4)2Ce(NO3)6 modification can restrain the loss of SO42- efficiently. The optimum calcination temperature and molar ratio of Ce(NH)∶Zr for SO42-/ZrO2 catalyst modified by (NH4)2Ce(NO3)6 are 450 ℃ and 2, respectively. 相似文献
10.
Ashani Kuttan 《Tetrahedron letters》2004,45(12):2663-2665
Reaction of N-Boc amino acids with ceric ammonium nitrate in an alcohol as the solvent at room temperature resulted in the esterification of N-Boc amino acids with Boc group retention. When the reaction was conducted at reflux temperature, esterification was accompanied with simultaneous removal of the Boc group. Both reactions gave the desired products in good yields. 相似文献
11.
Y. Pelovski 《Journal of Thermal Analysis and Calorimetry》2000,60(1):53-58
The development of equipment for thermal analysis has opened up new areas for applications in science, industrial practice and environment studies. On the basis of the literature and information from equipment producers, the directions for the use of thermal analysis in research and practice are classified. Special attention is paid to the possibilities of controlling environmental pollution, and the stability and other properties of intermediate and final industrial products. It is stressed that DSC and DTA systems can be successfully applied to determine enthalpy changes in raw materials and products as control tests for their application. The advantages of coupled thermal systems for complex studies and the control of raw materials, products and wastes are described. This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
12.
The maturity of Camellia oleifera fruit is one of the most important indicators to optimize the harvest day, which, in turn, results in a high yield and good quality of the produced Camellia oil. A hyperspectral imaging (HSI) system in the range of visible and near-infrared (400–1000 nm) was employed to assess the maturity stages of Camellia oleifera fruit. Hyperspectral images of 1000 samples, which were collected at five different maturity stages, were acquired. The spectrum of each sample was extracted from the identified region of interest (ROI) in each hyperspectral image. Spectral principal component analysis (PCA) revealed that the first three PCs showed potential for discriminating samples at different maturity stages. Two classification models, including partial least-squares discriminant analysis (PLS-DA) and principal component analysis discriminant analysis (PCA-DA), based on the raw or pre-processed full spectra, were developed, and performances were compared. Using a PLS-DA model, based on second-order (2nd) derivative pre-processed spectra, achieved the highest results of correct classification rates (CCRs) of 99.2%, 98.4%, and 97.6% in the calibration, cross-validation, and prediction sets, respectively. Key wavelengths selected by PC loadings, two-dimensional correlation spectroscopy (2D-COS), and the uninformative variable elimination and successive projections algorithm (UVE+SPA) were applied as inputs of the PLS-DA model, while UVE-SPA-PLS-DA built the optimal model with the highest CCR of 81.2% in terms of the prediction set. In a confusion matrix of the optimal simplified model, satisfactory sensitivity, specificity, and precision were acquired. Misclassification was likely to occur between samples at maturity stages two, three, and four. Overall, an HSI with effective selected variables, coupled with PLS-DA, could provide an accurate method and a reference simple system by which to rapidly discriminate the maturity stages of Camellia oleifera fruit samples. 相似文献
13.
为了制定富锂固溶体正极材料的生产工艺,需要对其前驱体中锰含量进行准确测定,以硝酸铵为氧化剂,采用磷酸固定锰的价态,用硫酸亚铁铵标准溶液滴定锰的容量法来测定锰含量,并对溶样方法及温度控制、磷酸的加入量、加入硝酸铵时的温度控制和硝酸铵的加入量等条件进行了优化实验,实验结果表明:称样量为0.300 0g,溶样消耗盐酸10mL,加入10mL H3PO4,溶液温度240℃时加入1.2g硝酸铵进行氧化,测定准确度最高,加标回收率为99.70%~100.5%,相对标准偏差小于0.24%,方法耗时短,不需要加入任何掩蔽剂,适合实际分析采用。 相似文献
14.
Phase Modification of Ammonium Nitrate by Potassium Salts 总被引:1,自引:0,他引:1
Modification of the room temperature phase (IV-III) of ammonium nitrate (AN) has been attempted using a variety of potassium salts namely, KF, KCl, KI, KNO3, K2CO3, K2SO4, KSCN and K2Cr2O7. No phase transition was observed when AN containing 1–2% by mass of these potassium salts is heated from room temperature (25°C) onwards in DTA and DSC scans, but the linear expansion due to phase transition was still observable in TMA measurements. Complete arrest of the linear expansion occurs only when a higher concentration of the additive is used. Similarly, in thermal cycling experiments, complete phase modification in the temperature range -80 to 100°C occurs only with a higher percentage of the potassium salt. The extent of modification, however, is found to be dependent both on the concentration, and the type of the anion. Potassium dichromate when used as an additive modifies the phase as well as the decomposition pattern of AN. This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
15.
High-resolution thermogravimetry was used to study the thermodesorption of octane from ammonium nitrate (AN) prills with different
porosities. The samples were wetted by immersion in octane. Multiple steps were obtained from the measured mass-loss curves,
which reflect the evaporation of the excess liquid, as well as the thermodesorption of octane from the pores and the surface
of the AN prills. The quantity of octane desorbed in these steps was correlated with the volume in the pores and the amount
adsorbed on the surface, and used to estimate the adsorption capacity, porosity and surface area of AN prills. The results
were also compared to observations from scanning electron microscopy.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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17.
在水-乙腈混合溶剂中用(NH~4)~2Ce(NO~3)~6氧化烷基蒽. 甲基, 乙基和环丙基蒽经历氧化-水解-氧化-水解-消除-氧化-去质子历程, 得到蒽环氧化产物, 消除烷基(或氢原子)的可能顺序是:H>CH~3>C~2H~5. 当蒽环的1,9-位连着1,2-亚乙基桥时, 却经由氧化-去质子-氧化水解-氧化(或消除)历程, 得到侧链氧化产物. 烷基的本质对多核芳烃的氧化机理有显著的影响. 相似文献
18.
铵梯脲混合炸药中改性硝酸脲和硝酸铵含量的测定 总被引:1,自引:0,他引:1
论述了铵梯脲混合炸药中改性硝酸脲和硝酸铵组分含量的一种快速准确的化学分析测定方法。该法在研制和生产铵脲类炸药的过程中,对选择最佳配比,控制生产和质量把关等有着重要的指导作用。同时笔者对测定方法,反应原理,影响因素等作了深入的探讨与研究。 相似文献
19.
考察了无机添加剂对农用硝酸铵拒爆性的影响。结果表明,当硝酸铵中添加3%的无机改性剂GXJ 1和10%的无机改性剂GXJ 2后,其拒爆性能明显增强;改性后的硝酸铵按照工业炸药配方配制成铵油炸药,不能被8号雷管起爆。而且改性后的硝酸铵颗粒强度高,不易粉化、结块和吸潮,具有优良的肥料品质。经济效益分析也表明,改性硝酸铵具有广阔的市场应用前景。通过X射线衍射分析、扫描电子显微镜分析等对改性硝酸铵进行了表征,并对拒爆机理进行了初步探讨。 相似文献