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1.
石墨炉原子吸收光谱法测定灵芝饮料中痕量锗 总被引:1,自引:0,他引:1
研究了用石墨炉原子吸收光谱法测定灵芝饮料中痕量锗,提出了以NaOH、H_2O_2为消解液分解样品,采用NaOH+Ni(NO_3)_2混合基体改进剂在热解涂层石墨管中直接测定灵芝饮料中痕量锗的方法。该法简单、快速、灵敏度高、重现性好。 相似文献
2.
基体改进剂效应塞曼无火焰原子吸收光谱法测定化探样品中痕量银 总被引:1,自引:0,他引:1
地球化探样中痕量银(0.0X ppm)不经分离富集直接测定是困难的。现有文献多采用分离富集处理后用无火焰原子吸收测定。采用基体改进剂手段,但未见用于任何样品中痕量银的分析。本文应用基体改进剂技术研究了痕量银在石墨炉原子吸收测定中的原子化条件和基体的干扰及排除。试验了用铱、钯、铂等作为基体改进剂,当加入15微克铱时,灰化温度可提高至1000℃。拟定了加入基体改进剂后的直接测定程序。本法灵敏度为4.5×10~(-12)g/l%,测定 相似文献
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微波消解样品-石墨炉原子吸收光谱法测定蜂产品中铅、镉、硒 总被引:1,自引:0,他引:1
提出了石墨炉原子吸收光谱法测定4种蜂产品中硒、铅和镉的含量.样品用浓硝酸、过氧化氢浸泡后,加热溶解,补加浓硝酸、过氧化氢进行微波消解.在优化的石墨炉工作条件下,用磷酸二氢铵作基体改进剂测定铅和镉,用PdCl2和Mg(NO3)2作混合基体改进剂测定硒.铅、镉和硒的检出限(3S/N)分别为11.3,1.9,3.7 ng,应用此方法分析了4种蜂产品样品,并用标准加入法作回收试验,测得铅、镉、硒的回收率分别为95.4%~103.8%,89.0%~110.0%,86.8%~96.5%之间,相对标准偏差均小于6%. 相似文献
6.
石墨炉原子吸收光谱法测定水中痕量硒 总被引:6,自引:0,他引:6
硒是人体必需的微量元素 ,适量硒可降低癌症和心血管疾病的发病率 ,但硒含量过高可引起中毒性病变[1 ] 。对于硒的测定 ,通常采用可见光及荧光吸光光度法[2 ] ,这些方法需要用有机溶剂萃取 ,操作较麻烦 ,且采用消化法处理样品时 ,容易导致硒的挥发损失。火焰原子吸收光谱法测定水中硒 ,灵敏度较低 ,而将以钯等作改进剂的石墨炉原子吸收法 [3]用于水中硒的测定 ,吸光度虽有所提高 ,但灵敏度仍难以满足水中痕量硒的测试要求。本文采用平台石墨管与基体改进剂结合技术 ,对水中痕量硒测定 ,结果满意。1 试验部分1 .1 主要仪器与试剂美国 TJA… 相似文献
7.
建立石墨炉原子吸收光谱法直接测定铁镍基高温合金中的锡元素。通过研究基体效应、溶样酸、基体改进剂、灰化温度、原子化温度以及不同激发光源类型,确定最佳测定方案:用2 m L盐酸和0.4 m L硝酸溶解合金样品,灰化温度为1 200℃,原子化温度为2 200℃,选用0.003 mg Pd(NO_3)_2和0.03 mg NH_4H_2PO_4作为基体改进剂。在空心阴极灯(HCL)和无极放电灯(EDL)两光源条件下,标准工作曲线的线性相关系数均大于0.999,分别对GBW 01632和GBW 01634的测定结果与认可值进行t检验(α=0.05),均无显著性差异,短期稳定性好(RSD5.0%,n=8),锡的检出限分别为0.82μg/L(HCL)和0.75μg/L(EDL)。该方法无需萃取或其它复杂的前处理过程,测定结果准确、可靠,可实现铁镍基合金样品中锡的直接测定。 相似文献
8.
建立了石墨炉原子吸收法直接测定加氢催化剂中痕量砷的方法,并研究了测定条件和消解方法。样品催化剂经HNO3-HClO4消解处理后,以Ni作为基体改进剂,用偏振塞曼效应扣去背景法测定其中的砷。砷的检出限为0.00048mg/L,样品测定结果的相对标准偏差小于2.2%(n=10),回收率为98%~101%。 相似文献
9.
地球化学样品中痕量镉(0.0Xppm)不经分离富集直接用无火焰原子吸收法测定是困难的。现有文献多采用分离富集后才能测定,或加入基体改进剂,我们曾在此基础上进行试验与探讨,但基体干扰仍未能消除。我们发现,用硫脲-EDTA盐-磷酸二氢铵作为基体改进剂,能消除基体干扰且提高了镉的原子化效率,无需分离富集可直接测定地球化探样品中痕量镉。用拟定的方法测定地球化学标准样中镉的结果与可用值相符,本法灵敏,快速、能满 相似文献
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A. V. Tvardovskii A. A. Fomkin Yu. I. Tarasevich I. G. Polyakova V. V. Serpinskii I. M. Guseva 《Russian Chemical Bulletin》1992,41(6):987-991
The changes in the thermodynamic functions of the sorbents were calculated for the first time from measurements of the deformations of vermiculite during the sorption of water vapor and adsorption-calorimetric data.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Institute of Colloid Chemistry and the Chemistry of Water, Academy of Sciences of the Ukraine, 252180 Kiev. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1270–1275, June, 1992. 相似文献
12.
农地“三权分置”政策入法关涉《农村土地承包法》修正和民法典物权编之编纂,已完成大修的《农村土地承包法》有其亮点,但对其与民法典物权编的关系尚未妥当处理,立法者在法律规则设计中亦没能体悟透彻政策意蕴。其制度设计有违在立法中的规范作用,混淆民法物债二分的基本原理,忽视法体系化与协调适用的要求,对乡村重要实际问题的系统解决态度有轻怠之嫌。落实农地“三权分置”政策的应然立法路向及其解释是:与“落实集体所有权”精神有效衔接,重申并进一步确立土地承包经营权的科学地位,精确界定土地经营权的内容和性质,为农地规模经营亟需的金融担保提供法治的正当性的支持。 相似文献
13.
We have summarized results of many experimental investigations of the thermodynamics of ionization of H2O(liq.) from 0–300°C and from 1.0 atm to nearly 8000 atm. Results of these investigations (equilibrium constants, enthalpies of ionization, heat capacities, partial molal volumes, and compressibilities) have been used for a number of thermodynamic calculations. It is particularly noteworthy that it is possible to use thermal data from 0–145°C with an equilibrium constant for 25°C in calculating reasonably accurate equilibrium constants for temperatures as high as 300°C. Similarly, it is possible to use volumetric data that refer to 1.0 atm in calculating useful equilibrium constants that apply for pressures as high as 2000 atm.Much of the work reported here was done while the author was on leave at the University of Lethbridge. 相似文献
14.
Earl M. Woolley John O. Hill William K. Hannan Loren G. Hepler 《Journal of solution chemistry》1978,7(5):385-393
We have made calorimetric measurements of enthalpies of dilution of aqueous iodic acid and have used these results for evaluation of the standard enthalpy of ionization of HIO3(aq.). We have also made calorimetric measurements of enthalpies of addition of perchloric acid solution to aqueous solutions of KIO3, KNO3, NaIO3, and NaNO3 and have used these results to obtain further values for the standard enthalpy of ionization of HIO3(aq.). On the basis of all these results, we have selected Ho=–660±125 cal-mole–1 as the best available standard enthalpy of ionization of HIO3(aq.) at 298.15°K, compared to the previously accepted –2400 cal-mole–1. Using the best available K=0.157 for ionization, we also obtain Go=1097 cal-mole–1 and So=–5.9 cal-oK–1-mole–1 for ionization of HIO3(aq) at 298.15°K.On study leave from Department of Inorganic and Analytical Chemistry, LaTrobe University, Bundoora, Victoria, 3083, Australia, to University of Lethbridge.On study leave from Department of Chemistry, University of Wollongong, Wollongong, N.S.W. 2500, Australia, to University of Lethbridge. 相似文献
15.
Sergey P. Verevkin Wei-Hong Peng Hans-Dieter Beckhaus Christoph Rüchardt 《Structural chemistry》1996,7(5-6):397-404
The standard enthalpies of combustion c
H
o of aliphatic diacetates1 and aromatic diacetates2 were measured calorimetrically. The enthalpies of vaporization vap
H
o or sublimation sub
H
o of1 and2 were obtained from the temperature function of the vapor pressure measured in a flow system. From f
H
o(g) of1 and2 new values of group increments for the estimation of standard enthalpies of formation of these classes of compounds were derived. The geminal interaction energy between the geminal acyloxy groups shows no anomeric stabilization.Geminal Substituent Effects, Part 12, for part 11 see Ref. 7. 相似文献
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An equation for the internal pressure acting on an adsorbate in micropores was obtained on the basis of the assumption that the chemical potential of an adsorbate in micropores is equal to that in an equilibrium gas phase and using the Dubinin-Radushkevich equation. The empirical relation between the characteristic adsorption energy and the half width of pores was expressed in terms of internal pressure and diameter of adsorbate molecules. The two-dimensional pressure was calculated for micropores with plane-parallel walls, where the width of a micropore coincides with the diameter of an adsorbate molecule. The results obtained were compared with the two-dimensional pressure of a monolayer on a free planar surface for an adsorbate and adsorbent of the same nature.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1928–1930, October, 1995. 相似文献
17.
W. Zielenkiewicz A. Zielenkiewicz K. L. Wierzchowski 《Journal of solution chemistry》1993,22(11):975-981
Enthalpies of solution in water H
sol
o
and enthalpies of sublimation H
sub
o
were determined for a number of crystalline derivatives of uracil: 1,6-dimethyluracil (m
2
1,6
Ura), 1,3,6-trimethyluracil (m
3
1,3,6
Ura), 6-ethyl-1,3-dimethyluracil (e6m
2
1,3
Ura), 6-propyl-1,3-dimethyluracil (pr6m
2
1,3
Ura) and 6-butyl-1,3-dimethyluracil (but6m
2
1,3
Ura). Standard enthalpies of hydration H
hydr
o
and standard enthalpies of interaction H
int
o
of the solutes with their hydration shells were calculated. The data obtained show that dependence of H
int
o
on the number of-CH2- groups of n-alkyl chain added upon substitution of diketopyrimidine ring is nonlinear. This finding is discussed in connection with results of X-ray diffraction structure determinations for the crystalline compounds. 相似文献
18.
G. Venkoba Rao M. Balakrishnan N. Venkatasubramanian P. V. Subramanian V. Subramanian 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):83-85
Abstract The signals for the α, β, and γ protons of pyridine exhibit a downfield shift in DMSO-d6, compared to CCl4 as solvent, the order being γ > β > α. This is attributed to an interaction between the positive end of the DMSO dipole and the lone pair of electrons on the ring nitrogen. This effect is also reflected in the faster rate of alkaline hydrolysis of ethyl isonicotinate over ethyl nicotinate and ethyl picolinate in aqueous DMSO relative to aqueous ethanol. Similar solvent effects are also observed in the pmr spectrum of pyrazine. 相似文献
19.
The protonation of leucoemeraldine in power form and in N-methylpyrrolidinone (NMP) solution by HCIO4 and HBF4 has been studied by x-ray photoelectron spectroscopy (XPS), infrared (IR), and ultraviolet (UV)-visible absorption spectroscopy. In powder form, less than 25% of the amine nitrogens can be protonated in the absence of oxygen. The effects of oxygen on the degree of protonation and the distribution of amine and imine units upon deprotonation of the salt are investigated. The degree of protonation in leuccemeraldine can be increased to about 50% with 3 M HCIO4, similar to that achievable with emeraldine base in powder form. In NMP solution, leucoemeraldine is easily oxidized by dissolved oxygen. Protonation of both leucoemeraldine and emeraldine base in NMP solutions results in metastable species which gradually undergo deprotonation. The resulting products are affected by the O2 content of the solutions. © 1993 John Wiley & Sons, Inc. 相似文献
20.
根据盐类水解关系式和水的离子积计算公式,建立了计算盐类水解度和水解产物离解常数的完全方程式。计算值同实验值比较,钾明矾溶液水解度平均偏差为0.6%,离解常数pK_b=11.6±0.1,水的离子积pK_w平均偏差小于0.06,从而改进了苏联的计算公式。 相似文献