Determination of vitamin C in effervescent tablets containing other vitamins together with trace elements

A simple, rapid method is reported for the determination of vitamin C in effervescent tablets containing other vitamins and several trace elements such as Mg(II), Zn(II), Fe(II), Mn(II), Cu(II) and Mo(VI). The procedure was developed on the basis of the bromate ion-iodide ion-ascorbic acid clock reaction (Landolt reaction). Interference effects of air oxygen and metal ions and the role of pH are discussed in detail.     

Purification of nickel sulfate using chelating ion exchangers and weak-base anion exchangers

Different types of chelating ion exchangers and weak-base anion exchangers were used in nickel sulfate purification from mixtures with Cu(II), Zn(H), Mn(II), Fe(III) by frontal analysis. Of the ion exchangers examined, the most suitable for selective separation of Cu(II) from NiSO, proved to be the amidoxine ion exchanger — Duolite ES-346, the polyethylenimine exchanger — Diaion CR-40, the macroreticular ion exchanger of the amino-acid type — Lewatit TP-207, and the polyfunctional weak-base anion exchanger — Merck II. Nickel sulfate is easily purified from Fe(III) on the amidoxine ion exchanger Duolite ES-346. The phosphonic ion exchanger Duolite ES-63 proved to be the most effective in Zn(H), Mn(II) and also FeIIII) separation. An amount of 10 kg of NiSO, was purified on 11 of this exchanger (in one run) under the optimal conditions, decreasing the content of copper and iron to < 0.0001%,, and zinc and manganese to < 0.001%.     

The effect of impurities on the extraction of copper from sulfate medium using LIX®984N in kerosene

In this research, the effect of impurities such as Zn(II), Mn(II), Fe(III) and Fe(II) on the extraction of copper using LIX®984N in kerosene has been evaluated. Hence, a series of extraction tests have been conducted to determine the effects of each foreign ion on copper extraction. It was found that the extraction of copper from sulfate media by the exractant LIX®984N in kerosene is completely pH dependent to pHs around 2.18 vol % of LIX®984N was found to be optimum for the maximum extraction efficiency of copper and 93.9% extraction was achieved at the end of 600 seconds. The order of extraction of different ions in pHs around 2 by the extractant LIX®984N was found to be as: Cu(II) > F(III) > Mn(II) > Fe(II) > Zn(II). For pHs greater than 2.5, the order of extraction will be changed as Cu(II) > Fe(III) > Mn(II) > Zn(II) > Fe(II) and this order for the pHs ≥ 4.5 was as Cu(II) > Fe(III) > Zn(II) > Fe(II) > Mn(II) which offers a good separation of ions using LIX®984N.     

电感耦合等离子体原子发射光谱法测定钼铌合金中8种元素

采用5.0 mL氢氟酸和10.0 mL硝酸混合酸消解样品,选择Ce 407.570nm、Cu217.895nm、Fe 234.350nm、Er 390.631nm、Mg 383.829nm、Mn 257.610nm、Pb 283.305nm、Zn 213.857nm为分析线,使用电感耦合等离子体原子发射光谱法(ICP-AES)进行测定,从而建立了电感耦合等离子体原子发射光谱法测定钼铌合金中Ce、Cu、Fe、Er、Mg、Mn、Pb、Zn等8种元素的分析方法。考察了主要元素Mo、Nb和Al对待测元素的影响,结果表明,这些元素对待测元素基本无影响。各元素校准曲线的线性相关系数均大于0.999;方法中各元素检出限为5.4~63μg/g。按照实验方法测定钼铌合金样品中Ce、Cu、Fe、Er、Mg、Mn、Pb、Zn,结果的相对标准偏差(RSD,n=6)为0.89%~4.4%;回收率为98%~102%。按照实验方法测定钼铌合金样品中Cu、Fe、Er、Mg、Mn、Pb、Zn、Ce,并与电感耦合等离子体质谱法(ICPMS)的测定结果进行比对,二者基本一致。     

超纯氧化铁制备及其在电感耦合等离子体原子发射光谱法测定高纯铁化合物中杂质元素的应用研究

用电感耦合等离子体原子发射光谱法(ICP-AES)准确测定高纯铁化合物中的痕量杂质元素,需要更高纯度的铁作为基体,以研究它对测定杂质元素的干扰。为此,以分析纯硫酸亚铁为原料制备了高纯氧化铁,制得的高纯氧化铁中杂质元素Al、Cd、Co、Cr、Cu、Mg、Mn、Ni和Zn等的含量低于方法检出限。用制备的高纯氧化铁作为标准系列溶液的基体,得到了基体匹配的标准系列溶液,用此标准系列溶液绘制的校准曲线测定了GBW01402d高纯铁标准物质中杂质元素的含量,其测定值与认定值一致。研究了用无基体匹配标准溶液测定高纯铁及铁化合物中Al、Cd、Co、Cr、Cu、Mg、Mn、Ni和Zn等杂质时的干扰校正方法,结果表明:Al、Co、Cr、Cu、Mg和Zn受到的光谱干扰仅需采用离峰法校正即可,而Cd、Mn和Ni受到的光谱干扰则必需采用多元光谱拟合法校正。用拟定的校正方法测定高纯铁化合物中的痕量杂质元素,准确度高的元素有Al、Cd、Cr和Cu,准确度稍差的元素有Co、Mg、Mn、Ni和Zn。     

Hydrolytic stripping of single and mixed metal-versatic solutions

Hydrolytic stripping is the process whereby metal ions in a loaded solvent extractant are directly precipitated as oxides or hydroxides by hydrolysis with water, typically at 130° to 200 °C. Hydrolytic stripping tests were carried out in sealed tubes at 200 °C on Versatic 10 solutions of Mg, Ca, Sr, Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Cd, singly and in mixtures. Single solutions of Fe, Ni, Cu, Mg, and Mn precipitated αFe₂O₃, Ni(OH)₂, CuO + Cu₂O, Mg(OH)₂, and γMn₂O₃, respectively, during testing. Several mixtures of iron with other metals precipitated magnetic spinel ferrites, MFe₂O₄. No other combinations of metals formed crystallographically distinctive mixed oxides.     

多元光谱拟合校正-电感耦合等离子体原子发射光谱法测定铱化合物中19种杂质元素

铱化合物产品中杂质元素的准确测定,是判定产品级别的重要指标,以往常采用摄谱法进行测定,但Ca、Si、Mg、Fe、Na测定结果准确性差,周期较长。根据铱化合物易溶于水及酸的性质,采用盐酸溶解样品,电感耦合等离子体原子发射光谱法(ICP-AES)测定了三氯化铱、四氯化铱、氯铱酸、氯铱酸铵等铱化合物中Pt、Pd、Ru、Rh、Ag、Au、Cu、Fe、Zn、Ni、Mn、Mg、Al、Ca、Sn、Na、Si、Pb、K等19种杂质元素。基体Ir对Pt、Sn产生的光谱干扰采用多元光谱拟合(MSF)方法校正,杂质元素间没有干扰。方法的检出限(μg/mL)为0.078(Pt)、0.0080(Pd)、0.014(Ru)、0.031(Rh)、0.0029(Ag)、0.016(Au)、0.0035(Cu)、0.012(Fe)、0.014(Zn)、0.0098(Ni)、0.0010(Mn)、0.0022(Mg)、0.0016(Al)、0.021(Ca)、0.057(Sn)、0.020(Na)、0.11(Si)、0.014(Pb)和0.0083(K)。按照实验方法测定三氯化铱中Pt、Pd、Ru、Rh、Ag、Au、Cu、Fe、Zn、Ni、Mn、Mg、Al、Ca、Sn、Na、Si、Pb、K等19种元素,结果的相对标准偏差(RSD,n=9)为1.2%~7.4%;加标回收率在89%~114%之间。     

Selective activation of calcineurin by dipicolinic acid

Calcineurin was activated at 30 degrees C by incubation with dipicolinic acid, a metal chelator, in the absence of activating, exogenous Mn2+. The activation reached a plateau after 90 min with 8- to 12-fold higher activity. Inclusion of the activating metal Mn2+ (1.0 mM) in the incubation mixture slightly lessened the activation induced by dipicolinic acid. The chelator 1,10-phenanthroline had no effect on the activity of calcineurin in concurrent experiments. Activation by dipicolinic acid was reversed by the addition of Zn2+ or Fe3+. The reversal occurred within 30 min after the addition of either metal and returned the activity of calcineurin to its initial level. Atomic absorption spectrometry analysis showed no loss of iron or zinc from calcineurin after activation (2 h) by dipicolinic acid. Because there seemed to be no interaction between dipicolinic acid and exogenous metal, the effect of dipicolinic acid was concluded to result from masking of at least one intrinsic metal. Calcineurin incubated with 1.0 mM Mn2+ (saturating levels) also did not show any loss of intrinsic metal by atomic absorption analysis. The consequences of these data concerning the role(s) of intrinsic metals in calcineurin catalysis are discussed.     

EDTA容量法测定铝合金中的镁

试样以氢氧化钠溶解，使铝、锌转入溶液并与铜、铁、锰、镁等氢氧化物沉淀分离。将沉淀以酸溶解并调节溶液酸度近中性，用DDTC分离铜、铁、锰，然后在PH10的氨性溶液中。以铬黑T为指示剂，用EDTA标准溶液直接滴定镁，测试铝合金中镁的含量。     

Carbonic anhydrase inhibitors: inhibition of isozymes I, II and IV with heterocyclic mercaptans, sulfenamides, sulfonamides and their metal complexes

A series of sulfenamides, sulfonamides and sulfonamide metal complexes have been prepared starting from 4,5-disubstituted-3-mercapto-1,2,4-triazole derivatives. The heterocyclic mercaptans were oxidized to the corresponding sulfenamides by hypochlorite in the presence of ammonia. The sulfonamides were obtained by oxidation of sulfenamides with potassium permanganate. The Zn(II) and Cu(II) complexes of the new heterocyclic sulfonamides have been prepared via the sodium salt of the ligand. Inhibition of three carbonic anhydrase (CA) isozymes, hCA I, hCA II and bCA IV (h = human, b = bovine) with the prepared compounds has been investigated. Mercaptans were generally less inhibitory than sulfenamides, which in turn behaved as weaker inhibitors than the sulfonamides. The strongest inhibitors were the Zn(II) and Cu(II) complexes of the heterocyclic sulfonamides. Susceptibility to inhibition was generally: hCA II > bCA IV > hCA I. Although none of the obtained simple inhibitors (mercaptans, sulfenamides, sulfonamides) possessed antiglaucoma action when administered directly into the eye in experimental animals, the Zn(II) and Cu(II) complexes of some sulfonamides acted as more efficient intraocular pressure lowering agents as compared to the clinical drug dorzolamide. This constitutes an encouraging result for obtaining novel antiglaucoma drugs from this class of CA inhibitors.     

Adrenoleucodystrophy: dermatological findings and skin surface lipid study

Co(II), Ni(II), Cu(II) and Zn(II) complexes of levamisole (LMS) were prepared and characterized by elemental analyses, IR spectroscopy, 1H and 13C NMR and mass spectrometry. The following general formula was derived: M(LMS)2Cl2, where M = Co, Ni, Cu, Zn. It was established that LMS behaved as a monodentate ligand and the coordination was accomplished through the N-7 atom. The toxicity and the immunomodulating activity of the complexes on mice and rats in comparison with uncomplexed LMS was assayed. The metals in the complexes exerted different changes in the toxicity of LMS. The complex containing Zn(II) was less toxic and manifested higher immunomodulating activity than LMS.     

Calculation of phase diagrams of systems Al-Cu-Zn-Mg and Al-Cu-Zn-Mg-Fe-Si

Fragments of phase diagrams Al-Cu-Zn-Mg and Al-Cu-Zn-Mg-Fe-Si-(Mn) in a temperature range (%) 4–6 Cu, 2–4 Zn, 0.5–2.0 Mg, 1.5–2.0 Fe, and 1.5–5.0 Si are constructed and the composition of the solid solution for a series of alloys of the Al-Cu-Zn-Mg-Fe-Si-(Mn) system at temperatures near the solidus is calculated by the results of thermodynamic calculations using the ThermoCalc software package. The thermodynamic calculations are verified by electron probe microanalysis. This verification shows the satisfactory convergence of the calculated and experimental data. It is revealed that, with the ratio of iron and silicon concentrations Fe/Si = 0.5 for alloys of the Al-Cu-Zn-Mg-Fe-Si-(Mn) system, it is possible to obtain a maximally doped solid solution.     

Three-step isolation method for sensitive detection of enterovirus, rotavirus, hepatitis A virus, and small round structured viruses in water samples

The concentrations of total Fe, Cu, Mn, Zn, Pb, Cr, Ni and Ca in the whole blood of young male apprentices of a technical-professional school, who are exposed to low doses of fumes from manual metal arc welding of mild steel, were monitored over their 2 years of apprenticeship in order to evaluate the influence of occupational exposure on biological metal levels. The results were compared with those from a control group of the same sex and age and living in the same geographic area. For comparison, monitoring of the same metal levels in the hair of both groups of individuals were also carried out. In the apprentices, the mean metal concentrations in blood at the end of the study were statistically significantly higher for Cu, lower for Fe and Mn and similar for the remaining metals. The levels of Fe significantly decreased whereas the levels of Cu were significantly increased during the study. A systematic influence of the exposure period on the levels of Mn was not observed. All the metal concentrations measured in the blood and hair of both apprentices and controls fell in the very large range of published reference levels. Seasonal variation (higher levels in the summer) of the hair metal concentrations were observed for Mn, Cu, Pb, Ni, Zn and Ca.     

Anticonvulsant-induced changes in tissue manganese, zinc, copper, and iron concentrations in Wistar rats

Human epileptics have been reported to have low blood manganese (Mn) concentrations in comparison to nonepileptics, an observation that is important because Mn deficiency can increase seizure susceptibility in experimental animals. Factors that have been suggested to contribute to the low blood Mn levels in epileptics include anticonvulsant use, seizure-induced tissue redistribution of Mn, and genetics; in the present study, the first of these possibilities was tested. Wistar rats were fed semipurified diets containing diphenylhydantoin ([DPH] 3 g/kg diet), phenobarbital ([PB] 2 g/kg diet), or primidone ([PRIM] 3 g/kg diet) for 7 weeks, at which time they were killed and tissues collected and analyzed for Mn, zinc (Zn), copper (Cu), and iron (Fe) concentrations. In comparison to pair-fed rats, DPH- and PRIM-fed rats had significantly elevated liver Mn concentrations, while Mn concentrations in blood, brain, heart, and kidney were unaffected by anticonvulsant exposure. Changes in the concentrations of Zn, Cu, and Fe in specific tissues were also found. Overall, these findings suggest that the anticonvulsants tested do not lead to significant derangements in the metabolism of Mn.     

Characterization of Fe(III)-deferoxamine and Mn(II)-pectin as magnetic resonance imaging contrast agents

To find new contrast agents for magnetic resonance imaging (MRI), the spin-lattice relaxation time (T1)-reducing activities of metal complexes of EDTA, N-hydroxyethyethylenediamine-N,N',N'-triacetic acid (HEDTA), diethylenetriamine-N,N,N',N',N'-pentaacetic acid (DTPA), deferoxamine, mugineic acid, and pectin with Fe(III) or Mn(II) were investigated. Strong activity was found in Fe(III)-deferoxamine, Fe(III)-mugineic acid, or Mn(II)-pectin. In the actual MRI tomogram, Fe(III)-deferoxamine exhibited a contrast-enhancing effect comparable with that of Gd(III)-DTPA, and a much stronger effect was observed for Mn(II)-pectin. Fe(III)-deferoxamine and the Mn(II)-pectin appear to be candidates, respectively, as a new intravenous contrast agent and an oral gastrointestinal one.     

磷酸盐沉淀法除铬热力学研究

除铬是含铬电镀污泥湿法冶金过程重要步骤.针对磷酸盐沉淀法从溶液中净化除铬过程进行热力学分析,绘制了25 ℃时Me-P-H₂O(Me: Cr(III), Zn(II), Cu(II), Fe(II), Fe(III), Ni(II))系组浓度对数-pH图,利用热力学平衡图对磷酸盐沉淀法从含铁等金属元素中净化除铁和磷酸铬碱分解过程进行热力学分析.结果表明,pH值为1.0 ~ 5.0磷酸盐形成由易至难依次为Cr(III)>Fe(III) >Fe(II)>Ni(II)>Cu(II)>Zn(II); 磷酸盐沉淀法难以有效地将Cr(III)与Fe(III)分离,而可分离Cr(III)和Fe(II),且较优pH约为2;整个pH值范围Me-P-H₂O系可以分为难溶磷酸盐稳定区、Me(OH)_n稳定区; 高pH区磷酸盐中的Me转变为稳定的Me(OH)_n,实现磷酸盐碱分解.验证实验表明,加入1.1倍理论量的磷酸钠,控制沉淀pH值为2.0,铬、铁、锌、铜、镍沉淀率分别为94.12 %、5.51 %、0.33 %、0.22 %、0.34 %; 氢氧化钠分解磷酸铬时,磷、铬浸出率分别为90.63 %、5.10 %,实现磷铬有效分离.实验与理论基本相符.      

Open study of a diclofenac sodium prolonged-release in patients suffering from coxarthrosis

Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used for routine analysis of small samples of human milk. The concentrations of calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), phosphorus (P), and zinc (Zn) were determined in 203 milk samples from postpartum women at different stages of lactation after stepwise digestion in HNO3, HClO4, and H2O2 under heat. Validation of the procedure was achieved using certified reference material of bovine liver (NBS 1577) with mean recoveries of 103.5%. The concentrations of the above elements in milk matrix were comparable with previously reported values. The analytical results from breast milk will provide reference information for mineral studies of Brazilian mothers and breast-fed infants.     

A multi-element isotopic tracer assessment of true fractional absorption of minerals from formula with additives of calcium, phosphorus, zinc, copper and iron in young piglets

True fractional absorption of minerals was measured to determine the bioavailability of Zn, Fe, Mn and Se from liquid formulas fortified with stepwise additions of Ca and P (as Ca glycerophosphate and carbonate, Ca*P), and Zn, Cu and Fe (as sulfate salts). Growth, deposition of tracers in organs and bone mineral content of femurs as assessed by single photon absorptiometry were measured. Four-day-old piglets (n = 36) were randomly assigned to groups fed a basal diet or additions of Ca*P (Ca = 25, P = 18 g/kg dry diet), Ca*P+Zn (Zn = 0.04 g/kg), Ca*P+Zn+Cu (Cu = 0.007 g/kg) or Ca*P+Zn+Cu+Fe (Fe = 0.008 g/kg). Oral and intravenous administration of extrinsic isotopes of 59Fe, 54Mn, 65Zn, 75Se and 47Ca was followed by fecal monitoring for 15 d and true absorption calculated after accounting for endogenous excretion. Addition of Ca*P+Zn reduced Zn absorption (P < 0.05) and Ca*P+Zn+Cu reduced Fe absorption (P < 0.01), but Mn and Se absorptions were not altered. Uptake of only Zn tracer into heart was significantly different (P < 0.05) among diet groups. Weight gain and linear growth were similar in all groups. Addition of Ca*P produced higher bone mineral density, but its effect on Zn absorption warrants further investigation.     

Heme binding by a bacterial repressor protein, the gene product of the ferric uptake regulation (fur) gene of Escherichia coli

The fur gene product, Fur, of Escherichia coli is a repressor when it binds Fe(II). Since heme and iron metabolism are closely linked and Fur is rich in histidine, a ligand for heme, the binding of heme to Fur was investigated. The oxidized Fur-heme complex is stable and low spin with a Soret maximum at 404 nm and no 620-nm band. CO coordinates with the reduced heme-Fur complex, causing a shift from 412 nm to 410 nm, and stabilizes it, increasing the half-life from 5 to 15 min. Circular dichroism (CD) spectra in the Soret region show heme bound in an asymmetric environment in Fur, both in the oxidized and reduced-CO forms. Quenching of tyrosine fluorescence by heme revealed rapid, tight binding (Kd < 1 microM) with an unusual stoichiometry of 1 heme:1 Fur dimer. Fur binds Mn(II), a model ligand for the endogenous Fe(II), much more weakly (Kd > 80 microM). Far-ultraviolet CD spectroscopy showed that the alpha-helix content of apo-Fur decreases slightly with heme binding, but increases with Mn(II) binding. Competition experiments indicated that heme interacts with Fur dimers at the same site as Mn(II) and can displace the metal. In contrast to Mn(II), Zn(II) did not quench the tyrosine fluoroescence of Fur, affected the CD spectrum less than Mn(II), but did bind in a manner which prevented heme from binding. In sum, Fur not only binds heme and Zn(II) with sufficient affinity to be biologically relevant, but the interactions that occur between these ligands and their effects on Mn(II) binding need to be taken into account when addressing the biological function of Fur.     

Heterometallic hybrids of homometallic human hemoglobins

Hybridization experiments between normal Hb tetramers (Fe2+ Hb) and those with four metal-substituted hemes (i.e., replacement of Fe2+ by Co2+, Mg2+, Mn2+, Mn3+, Ni2+, or Zn2+) have revealed unexpected behavior. These homometallic Hbs have previously served as models that mimic the deoxy or oxy properties of normal Fe2+ Hb. In this study, hybrids were composed of one alpha 1 beta 1 dimer that is metal-substituted at both hemes, in association with a second dimer alpha 2 beta 2 that has normal Fe2+ hemes. Both metal-substituted subunits are unligated, whereas the two Fe2+ subunits either are both unligated or both ligated with O2, CO, or CN. It was found that four of the metal-substituted Hbs (Mg2+ Hb, Mn2+ Hb, Ni2+ Hb, and Zn2+ Hb) did not form detectable amounts of heterometallic hybrids with normal Fe2+ Hb even though (i) their homometallic parents formed tight tetrameric complexes with stabilities similar to that of Fe2+ Hb and (ii) hybrids with metal substitution at both alpha sites or both beta sites are known to form readily. This striking positional effect was independent of whether the normal Fe2+ hemes were ligated and of which ligand was used. These findings indicate that surprisingly large changes in tetramer behavior can arise from small and subtle perturbations at the heme sites. Possible origins of these effects are considered.