电感耦合等离子体质谱法测定卷烟用纸中铜、砷、钼、镉、铊和铅

采用电感耦合等离子体质谱法测定了卷烟纸中铜、砷、钼、镉、铊和铅等6种杂质金属元素。试样用硝酸、过氧化氢及氢氟酸在Multiwave 3000型微波消解仪中消解处理,在所得消解后的溶液中加入硼酸溶液络合过量的氢氟酸。加入含115In及209Bi各20μg.L-1的混合溶液作为内标。上述6种元素在一定浓度范围内与各相应的分析信号值之间呈线性关系,其检出限(3S/N)在0.002～0.16μg.L-1之间。按标准加入法测得方法的回收率在95.3%～113.0%之间。试验了方法的重复性,其相对标准偏差(n=5)在0.9%～4.6%之间。     

微波消解高碳铬铁样品及其中铬硅磷的测定

提出了微波消解法溶解高碳铬铁。将粒径小于0.076 mm样品0.200 0 g置于消解罐中,加入高氯酸5 mL,氢氟酸1 mL,按设定程序消解。于消解所得溶液中加入饱和硼酸溶液5 mL后,定容至200 mL。分取100.0 mL溶液用过硫酸铵氧化,硫酸亚铁铵标准溶液电位滴定法测定其铬量。另分取50.00 mL溶液,用电感耦合等离子体原子发射光谱法测定硅及磷量,选择251.612,213.618 nm分别作为测定硅和磷的分析线。按此方法分析了3个标准样品,测得结果与认定值一致。铬、硅、磷3元素测定值的平均相对标准偏差(n=6)依次为0.09%,0.49%和2.2%。     

微波消解-电感耦合等离子体原子发射光谱法(ICP-AES)测定高速工具钢中锰、磷、镍、铜、铬、钒

高速工具钢为高碳高合金工具钢,常温下样品酸溶分解较为困难,因此建立了微波消解电感耦合等离子体原子发射光谱法(ICP-AES)测定高速工具钢中锰、磷、镍、铜、铬、钒的方法,利用微波消解提高溶样的温度和压力,在王水、氢氟酸和硫酸介质中使样品充分消解,再用饱和硼酸溶液络合过量的氢氟酸,基体匹配消除铁基体的影响,ICP-AES法同时测定锰、磷、镍、铜、铬、钒的含量。测定高速工具钢标准样品,测定值与标样值相吻合,方法的相对标准偏差在0.55%~4.1%。加标回收率在95.6%~114.8%,满足测定要求。     

微波消解ICP-AES法测定高速工具钢中锰、磷、镍、铜、铬、钒

高速工具钢为高碳高合金工具钢,常温下样品酸溶分解较为困难。本文利用微波消解提高溶样的温度和压力,在王水、氢氟酸和硫酸介质中使样品充分消解,再用饱和硼酸溶液络合过量的氢氟酸,基体匹配消除铁基体的影响,ICP-AES法同时测定锰、磷、镍、铜、铬、钒的含量。测定高速工具钢标样,测定值与标样值相吻合,本方法的精密度在0.55%～4.06%。加标回收率在95.6%～114.8%,满足测定要求。     

微波消解-电感耦合等离子体原子发射光谱法测定木耳中铝的含量北大核心CSCD

摄入过多铝元素可能带来一定健康风险,而相关标准及文献中均缺乏木耳中铝含量的测定方法,故提出了题示方法,并对消解体系中氢氟酸的影响进行了讨论。取0.250 0 g烘干后的木耳样品于消解管中,加入5 mL硝酸、1 mL 30%(质量分数)过氧化氢溶液和0.5 mL氢氟酸,加盖后放置过夜,并于次日按照微波消解程序进行消解。赶酸、洗涤、用2%(体积分数)硝酸溶液定容,用电感耦合等离子体原子发射光谱法在396.152 nm检测波长下测定样品溶液中铝含量。结果显示,不加氢氟酸时铝的测定值显著低于认定值,而添加氢氟酸后的测定值均在认定值的不确定度范围内,铝的质量浓度在10.0 mg·L^(-1)内与其对应的发射强度呈线性关系,检出限为5.9μg·L^(-1);对生物成分分析标准物质进行精密度和加标回收试验,所得测定值的相对标准偏差(n=6)为4.0%~8.5%,回收率为89.0%~97.3%。方法用于10个木耳样品的分析,所得测定值为203~305 mg·kg^(-1)。     

微波消解-电感耦合等离子体质谱法同时测定铝土矿中11种金属元素

建立了微波消解-电感耦合等离子体质谱法(ICP-MS)同时测定铝土矿中锂、铬、铜、铁、钛、钾、钠、钙、镁、铅、锌等11种金属元素含量的方法。将铝土矿粉碎、研磨和干燥后,取0.1 g样品,加入3 mL硫酸、1 mL硝酸、2 mL氢氟酸和3 mL盐酸,按升温程序微波消解样品,加40 g·L~(-1)硼酸溶液10 mL,继续在120℃下消解10 min,使消解液变澄清。冷却后取出,180℃加热至近干,用1%(体积分数)硝酸溶液稀释,按照ICP-MS条件测定。通过用10 g·L~(-1)铝基体溶液配制混合标准溶液系列并加入内标元素Sc、Ge、Bi的方法来消除基体干扰,选择合适的待测元素同位素的方法来消除谱线重叠干扰。结果显示:11种元素的质量浓度均在一定范围内与其对应的响应值与内标元素响应值的比值呈线性关系,检出限(3s)为0.011～1.400 mg·kg~(-1)。对实际样品进行加标回收试验,测定值为0.13～72.21 mg·L~(-1),测定值的相对标准偏差(n=6)为0.69%～2.6%,回收率为94.0%～106%;此方法用于分析3种铝土矿成分分析标准物质GBW 07177、GBW 07179、GBW 07180,所得测定值均在认定值要求的范围内。     

微波消解-电感耦合等离子体原子发射光谱法测定膨润土中6种元素

膨润土样品用硝酸、盐酸、氢氟酸在超级微波消解仪中进行消解,消解完毕后加入高氯酸加热除去有机物、碳类。采用电感耦合等离子体原子发射光谱法测定样品溶液中钙、镁、磷、锰、铁、钛等6种元素的含量。6种元素的质量浓度在一定范围内与其对应的发射强度呈线性关系,方法的检出限(3s)为0.001~0.009mg·L-1。方法应用于膨润土样品的分析,测定值的相对标准偏差(n=11)为0.74%~2.7%。用标准加入法做方法的回收试验,测得回收率为96.0%~102%,方法测定值与X射线荧光光谱法测定结果相符。     

微波消解试样-氢化物发生-原子荧光光谱法测定铁矿石中砷

应用氢化物发生-原子荧光光谱法测定了铁矿石中微量砷。试样用硝酸、盐酸及氟氢酸的混合酸在微波消解仪中消解处理。经试验选定微波消解程序为:①消解功率650 V;②以5℃.min-1速率升温至170℃,保持20 min;③冷却20 min,在所得溶液中加入饱和硼酸溶液使游离氢氟酸络合,再加入硫脲及抗坏血酸溶液作掩蔽剂后定容为50 mL,在仪器工作条件下进行砷的测定。设置样品溶液的进样量为1.0 mL,10 g.L-1硼氢化钾溶液的加入量为0.5 mL。在制作标准曲线时加入一定量的铁以抵消基体铁的干扰。砷的质量浓度在0.90~100μg.L-1范围内与相应的荧光强度之间呈线性关系。方法的检出限(3s)为0.40μg.L-1。按所提出的方法测定了铁矿石标准样品中砷量,所得结果与认定值相符。     

电感耦合等离子体质谱同位素稀释法测定菜园土壤中微量镉

用电感耦合等离子体质谱同位素稀释法,测定了菜园土壤中微量镉的含量。土壤样品中加入一定量的112Cd富集同位素试剂后,用硝酸-氢氟酸-高氯酸混合酸预消解后再经微波消解,冷却后样品溶液在130℃蒸发近干,然后加入硼酸1 mL,以硝酸(2+98)溶液定容至20 mL,利用电感耦合等离子体质谱法测定溶液中的同位素比值R(112Cd/111Cd),用同位素稀释法计算出样品中镉的含量。试验对仪器参数1、12Cd富集同位素试剂的加入量、质量歧视因素、仪器死时间及同量异位素和多原子离子峰的干扰等因素对测定产生的影响进行了试验和校正。在优化的条件下测定了土壤标准物质(GBW 07423)中镉的含量,测定值与标准值相符。     

微波消解-电感耦合等离子体原子发射光谱法测定钒钛铁精矿中10种主次元素的含量

称取0.100 0g试样于聚四氟乙烯消解罐中,加入3mL盐酸,1mL硝酸,1mL氢氟酸,进行微波消解,消解完成后冷却,加入50g·L-1硼酸溶液10mL,继续消解3min后,将试液用水定容至100mL,采用电感耦合等离子体原子发射光谱法测定其中的钛、硅、铝、钙、镁、钒、锰、磷、镍和铬。运用基体匹配法消除了基体效应。各元素的质量浓度在一定范围内与分析谱线的强度呈线性关系,检出限(3s)在1.2~44μg·L~(-1)之间。采用本方法测定标准样品,结果与认定值相符,测定值的相对标准偏差(n=8)均小于5.0%。本方法对实际样品的测定值与湿法化学法及原子吸收光谱法测得结果一致。     

Determination of trace impurities in tin by neutron activation analysis

Two methods are described to determine indium and managenese in high-purity tin. In the first method indium and manganese are separated from the tin and antimony matrix activities on Dowex 1X8 anion exchanger. Tin and antimony are adsorbed in 10M HF while indium and manganese are eluted. In the second method the incident γ-ray intensity due to the tin matrix is reduced by placing a lead absorber between the sample and the detector. The reproducibility and the sensitivity of both methods are of the order of 10 ppb for manganese and of 1 ppb for indium for 1 g samples and a neutron flux of 10¹¹ n·cm⁻²·sec⁻¹. Aspirant of the N. F. W. O.     

KrF2/MnF4 adducts from KrF2/MnF2 interaction in HF as a route to high purity MnF4

In the system KrF₂—MnF₂—HF two new adducts, 2KrF₂·MnF₄ and KrF₂·MnF₄ have been synthesized. The 2 : 1 adduct decomposes in a dynamic vacuum at −45°C yielding KrF₂ and the 1 : 1 adduct, which is stable in a dynamic vacuum up to −25°C. KrF₂·MnF₄ decomposes further at room temperature to krypton, fluorine, krypton difluoride and manganese tetrafluoride. This reaction is a useful synthetic route for the preparation of pure manganese tetrafluoride.     

Cathodic electrochemiluminescence of metal ions in acid fluoride solutions

The conditions for exciting the cathodic electrochemiluminescence (ECL) of mercury-like ions and manganese in dilute HF solutions at aluminum and magnesium electrodes are described. ECL spectra are measured. It is shown that Mn(II) can be determined with a detection limit of 10^?7 M.     

美白祛斑化妆品中镉、锰、铜、锌的原子吸收光谱法测定

将美白祛斑化妆品在硝酸-过氧化氢或硝酸-过氧化氢-氢氟酸体系中经微波消解后,用原子吸收光谱法测定其中的镉、锰、铜、锌含量。结果表明,在特定的测定工作条件下,镉、锰、铜、锌分别在2.0、3.0、6.0、2.0 mg.L-1内与吸光值呈现良好的线性,其检出限分别为2.6、2.8、19.0、2.6μg.L-1(n=20)。该法用于测定美白化妆品的镉、锰、铜、锌元素上线性好,回收率高,分别在98.3%～101.2%、99.0%～102.7%、98.0%～101.3%、99.0%～103.0%,精密度好,其RSD分别为3.4%、5.5%、3.5%、4.7%(n=6)。     

Oxidation with permanganate in presence of fluoride potentiometric determination of manganese(II)

The effects of acidity, fluoride concentration, temperature and concentration of manganese in the reaction between KMnO(4) and Mn(II) were studied potentiometrically. The rate of reaction is increased by increasing the fluoride concentration and/or decreasing the acidity of the solution. The formal redox potentials of the MnO(-)(4)/Mn(III) and the Mn(III)/Mn(II) systems were determined at different pH values. The E degrees values obtained by extrapolation to pH = 0 were 1.58 and 1.52 V respectively. The amount of Mn(II) determined was varied from 5 to 56 mg. The net reaction can be represented as MnO(-)(4) + 10HF(-)(2) + 4Mn(2+) right harpoon over left harpoon 5MnF(-)(4) + 2H(+) + 4H(2)O.     

Genetic analysis of human complement factor H polymorphisms

Human complement factor H (factor H) is polymorphic, with five previously reported FH alleles and three previously reported HF alleles (HF*A, HF*B, and HF*Q0). The relationship between the FH and HF alleles is not clear, and the genetic basis of factor H phenotypes has not yet been identified. In this study, nucleotide sequence analysis of complementary DNA (cDNA) from individuals with each HF phenotype identified seven mutated sites in the factor H gene. However, in four cases, the same cDNA sequence was observed in individuals with two different HF phenotypes. Western blotting and 2-DE also showed that a 160 kDa protein corresponding to factor H was expressed in individuals with HF phenotypes. In addition, factor H cross-reacting 45 and 42 kDa polypeptides were detected in individuals with HF A, HF B, or HF AB phenotypes, but not in individuals with the HF Q0 (a null allele) phenotype. Thus, HF phenotype did not correlate well with factor H gene or protein structural variation. Evidence is provided to support the hypothesis that the HF phenotypes do not correspond to polymorphism in factor H, but instead correspond to polymorphism in factor H-related protein 1. A novel PCR-RFLP method was developed and used to detect four polymorphisms (G257A, G1492A, A2089G, and G2881T) in the factor H gene in 54 unrelated Japanese individuals. This method could be useful for studies on genetic disease associated with these mutations.     

Role of Hartree-Fock and Kohn-Sham orbitals in the basis set superposition error for systems linked by hydrogen bonds

In this work the effect of the basis set superposition error (BSSE) is explored with the counterpoise method on the occupied and unoccupied Hartree-Fock (HF) and Kohn-Sham (KS) orbitals. Three different systems linked by hydrogen bonds, H(2)O...FH, H(2)O...H(2)O, and H(2)O...CFH(3), were studied by using the basis set families cc-pVXZ and aug-cc-pVXZ (X = D, T, Q). The basis sets were tested with the HF method and two approximations for the exchange-correlation functional of KS: a generalized gradient approximation and a hybrid approach. In addition to these methods, the second-order M?ller-Plesset perturbation theory, MP2, was considered. It was found that the presence of the "ghost" basis set affects the orbitals in two ways: (1) The occupied KS orbitals are more sensitive to the presence of this "ghost" basis set than the occupied HF orbitals. For this reason the BSSE observed in HF is less than that obtained with KS. (2) The unoccupied HF orbitals are more sensitive to the presence of the "ghost" basis set than their corresponding occupied orbitals. Because the MP2 method uses both, occupied and unoccupied HF orbitals, to compute the total energy, the contribution of the BSSE is bigger than that obtained with HF or KS methodologies.     

Spectroscopy of HF and HF-containing clusters in solid parahydrogen

We report measurements of FT-IR absorption spectroscopy of HF, DF, and their clusters in solid parahydrogen (pH(2)). The observed spectra contain many absorption lines which were assigned to HF monomers, HF polymers, and clusters with other species, such as N(2), O(2), orthohydrogen (oH(2)), etc. The rotational constants of HF and DF monomers were determined from the cooperative transitions of the vibration of solid pH(2) and the rotation of HF and DF. Small reduction of the rotational constants indicates that HF and DF are nearly free rotors in solid pH(2). Time dependence of the spectra suggests that HF and DF monomers migrate in solid pH(2) and form larger polymers, probably via tunneling reactions through high energy barriers on inserting another monomer to the polymers. The line width of HF monomers in solid pH(2) was found to be 4 cm(-1), which is larger than that of other hydrogen halides in solid pH(2). This broad line width is explained by rapid rotational relaxation due to the accidental coincidence between the rotational energy of HF and the phonon energy with maximum density of states of solid pH(2) and the rotational-translational coupling in a trapping site.     

Structure and ultrafast dynamics of liquid water: a quantum mechanics/molecular mechanics molecular dynamics simulations study

A quantum mechanics/molecular mechanics molecular dynamics simulation was performed for liquid water to investigate structural and dynamical properties of this peculiar liquid. The most important region containing a central reference molecule and all nearest surrounding molecules (first coordination shell) was treated by Hartree-Fock (HF), post-Hartree-Fock [second-order Moller-Plesset perturbation theory (MP2)], and hybrid density functional B3LYP [Becke's three parameter functional (B3) with the correlation functional of Lee, Yang, and Parr (LYP)] methods. In addition, another HF-level simulation (2HF) included the full second coordination shell. Site to site interactions between oxygen-oxygen, oxygen-hydrogen, and hydrogen-hydrogen atoms of all ab initio methods were compared to experimental data. The absence of a second peak and the appearance of a shoulder instead in the gO-O graph obtained from the 2HF simulation is notable, as this feature has been observed so far only for pressurized or heated water. Dynamical data show that the 2HF procedure compensates some of the deficiency of the HF one-shell simulation, reducing the difference between correlated (MP2) and HF results. B3LYP apparently leads to too rigid structures and thus to an artificial slow down of the dynamics.     

Alkali-metal trifluoromonosulphatomanganates (III) A2[MnF3(SO4)] (A = NH4, Li,Na or K)

Pink-brown crystalline alkali-metal trifluoromonosulphatomanganates(III), A₂[MnF₃(SO₄)] (A = NH₄, Li, Na or K), have been synthesised in high yields by reacting KMnO₄ or MnO(OH) with 40% HF and A₂SO₄ or by the reaction of MnO(OH) with 40% HF and A₂S₂O₈ (A = NH₄ or K). The chemicallly estimated oxidation state of manganese occurs between 2.9 and 3.1, and the room temperature magnetic moments lie in the range 4.0–4.2 BM. (NH₄)₂[MnF₃(SO₄)] on being pyrolysed at 340°C yields MnSO₄.