Calculation of Conditional Equilibrium Constants of Reactions of Reduction of Titanium,Zirconium, and Hafnium Chlorides with Alkali Metals in a Melt of Their Chlorides

Equilibrium constants of the reactions of reduction of Ti, Zr, and Hf chlorides with metallic Li, Na, K, Rb, and Cs in their molten chlorides were calculated from published data.     

Trace elements in Variegated Bolete (Suillus variegatus) fungi

Metallic elements such as Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Rb, Sr, and Zn were determined using ICP-OES in a representative set of fifteen fruiting bodies of the edible fungus Suillus variegatus. Fruiting bodies were collected from unpolluted areas near the village of Lubichowo of the Bory Tucholskie forest complex in northern Poland in 2007?C2008. The caps were richer in Ag, Al, Cd, Cr, Cu, Fe, K,Mg, Ni, Rb, and Zn, and the stipes in Ba, Ca, Mn, Na, Pb, and Sr. Cobalt concentration in the caps and stipes was similar. In the caps, the content of the elements decreased in the order (mg per kg of dry weight): K 29000 ± 3700, Fe 1600 ± 80, Mg 990 ± 110, Rb 320 ± 86, Zn 90 ± 19, Ca 75 ± 34, Al 68 ± 32, Na 40 ± 18, Cu 19 ± 7, Mn 13 ± 7, Cd 1.0 ± 0.5, Ni 0.64 ± 0.32, Ag 0.40 ± 0.20, Cr 0.33 ± 0.06, Pb 0.20 ± 0.17, Ba 0.19 ± 0.11, Sr 0.15 ± 0.09, and Co 0.070 ± 0.050. Apparently, S. variegatus collected from background areas are relatively low in Pb and Cd and so are suitable for human consumption.     

Determination of trace elements of some Egyptian crops by instrumental neutron activation,inductively coupled plasma-atomic emission spectrometric and flameless atomic absorption spectrophotometric analysis

Instrumental neutron activation analysis was used for the determination of Al, Br, Ca, Ce, Cl, Co, Cr, Cs, Eu, Fe, K, La, Mg, Mn, Na, Rb, Sb, Sc, Se, Ti, Th, V and Zn, ICP-AES for the determination Al, Ag, Ba, Be, Ca, Co, Cr, Cu, Fe, Ga, K, Li, Mg, Mn, Na, Ni, P, Sc, Sr, Ti, V and Zn and flameless AAS for the determination of Cd, Hg and Pb in egg plant, potatoes, green pepper (Leguminosae), vegetable marrow (Cucurbitaceae), pears, apple (Rosaceae), castor oil plant (Euphorbiaceae), lettuce (compositae), dill, parsley, coriander (Umbelliferae), and in some soil samples collected from Aswan province.     

Instrumental neutron activation analysis of brewer's yeast

Instrumental neutron activation was used for the determination of 23 trace and minor elements in 4 different samples of brewer's yeast. Detection limits for these elements vary from 2 ppb to 100 ppm. The following average concentrations were found (ppm, dry weight): Al 597, Br 0.36, Cl 1473, Co 0.21, Cu 19, Fe 285, K 16 400, Mg 1355, Mn 8.4, Na 2330, Rb 19, Sb 0.053, Se 1.2, V 2.2 and Zn 80. NBS standard 1569 was also analyzed and the following concentrations (in ppm) were measured: Al 2300, Br 0.65, Ce 0.23, Cl 460, Co 0.26, Cr 2.12, Cu 11, Fe 707, Gd 7.1, Hf 0.13, K 15 500, Mg 1780, Mn 7, Na 510, Rb 16, Sb 0.075, Sc 0.18, Se 0.92, Th 3.7, Ti 38, U 0.49, V 4.1 and Zn 70.     

Multivariate analysis of trace elements determined in archaeological materials and its use for characterisation

Data on the concentrations of K, Ca, Ti, Fe, Cu, Zn, Ga, Rb, Sr and Zr obtained by PIXE and of B, F, Na, Mg, Al, Si and Cu obtained by proton-induced prompt gamma-ray spectrometry were used to characterize archaeological artefacts and source materials by multivariate analysis. The mathematical approaches employed were cluster analysis using nearest-neighbour data, multidimensional scaling and correspondence analysis.     

Application of nondestructive X-ray fluorescence analysis to determine the element composition of medicinal plants

A nondestructive X-ray fluorescence technique has been developed to determine Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Ba, and Pb in plants. The line element intensities were measured by an S4 Pioneer X-ray sequence spectrometer (Bruker AXS, Germany). The inversely proportional relationship was obtained between the analyte line intensity and mass of the plant, pressed on boric acid backing, for elements with an atomic number 11 < Z < 20. It was found that reduction of plant mass from 6 to 1 g leads to an increase in element determination sensitivity. The detection limits for 1 g of pressed plant were evaluated as μg/g: 5–20 (Na, Mg, Al); 1–4 (Si, P, S, Cl, K, Ca, Ti, Ba, Pb); 0.4-0.8 (Cr, Mn, Fe, Ni, Br, Cu, Zn, Rb and Sr). This technique was applied to determine the element composition of violets of Violaceae family, which are used in medicine.     

Accelerated denitration by formic acid accompanied with residual acid-electrolytic trimming

The fruit bodies of wild-growing higher fungi (macromycetes), commonly called mushrooms, of various genera and species collected in localities with different geochemical features and man-made burden in the Czech Republic were analyzed by different modes of activation analysis. The elements Na, Mg, Al, S, Cl, K, Ti, V, Mn, Cu, Br, Ba and Dy were determined by short-term instrumental neutron activation analysis (INAA). Short-term epithermal INAA (ENAA) was used for determination of I and other elements, such as Rb, Ag, and U. The elements Na, K, Sc, Cr, Fe, Co, Cu, Zn, As, Se, Br, Rb, Ag, Cd, Sb, Cs, Ba, La, Ce, Sm, Eu, Hf, Au, Hg and Th were determined by long-term INAA, whereas long-term ENAA enabled determination of several other elements, such as Ni, Ta, W and U. The analytical possibilities of instrumental photon activation analysis (IPAA) using a microtron were also explored and found useful for determination of several additional elements, namely Sr, Y, Zr, Nb, and Pb. High concentrations of several essential and toxic trace elements found (up to hundreds of mg^.g^-1, dry mass) should be of concern in nutritional studies, because mushrooms form non-negligible part of diet in many countries, especially in Middle and East Europe.     

Dating and classification of Syrian excavated pottery from Tell Saka Site,by means of thermoluminescence analysis,and multivariate statistical methods,based on PIXE analysis

Thermoluminescence (TL) dating and Proton Induced X-ray Emission (PIXE) techniques have been utilized for the study of archaeological pottery fragment samples from Tell Saka Site, which is located at 25 km south east of Damascus city, Syria. Four samples were chosen randomly from the site, two from third level and two from fourth level for dating using TL technique and the results were in good agreement with the date assigned by archaeologists. Twenty-eight sherds were analyzed using PIXE technique in order to identify and characterize the elemental composition of pottery excavated from third and fourth levels, using 3 MV tandem accelerator in Damascus. The analysis provided almost 20 elements (Na, Mg, Al, Si, P, S, K, Ca, Ti, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb). However, only 14 elements as follows: K, Ca, Ti, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb were chosen for statistical analysis and have been processed using two multivariate statistical methods, Cluster and Factor analysis. The studied pottery were classify into two well defined groups.     

Simultaneous PIXE and PIGME Analysis of a Nigerian Tar Sand Sample from a Deep Borehole

Tar sands from a deep borehole in southwestern Nigeria were subjected to elemental analysis by simultaneous proton induced X-ray emission (PIXE) and proton induced gamma-ray emission (PIGME) techniques. The concentration of 22 major, minor and trace elements, namely Al, Ca, Cr, Cu, F, Fe, Ga, Ge, K, Li, Mg, Mn, Na, P, Pb, Rb, S, Si, Sr, Ti, Zn and Zr were determined. The accuracy and precision of the techniques for chemical analysis were assured by analysing the NBS 278 geological standard.     

Evaluation of strontium isotope abundance ratios in combination with multi-elemental analysis as a possible tool to study the geographical origin of ciders

In order to evaluate alternative analytical methodologies to study the geographical origin of ciders, both multi-elemental analysis and Sr isotope abundance ratios in combination with multivariate statistical analysis were estimated in 67 samples from England, Switzerland, France and two Spanish regions (Asturias and the Basque Country). A methodology for the precise and accurate determination of the ⁸⁷Sr/⁸⁶Sr isotope abundance ratio in ciders by multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) was developed. Major elements (Na, K, Ca and Mg) were measured by ICP-AES and minor and trace elements (Li, Be, B, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Y, Mo, Cd, Sn, Sb, Cs, Ba, La, Ce, W, Tl, Pb, Bi, Th and U) were measured by ICP-MS using a collision cell instrument operated in multitune mode. An analysis of variance (ANOVA test) indicated that group means for B, Cr, Fe, Ni, Cu, Se, Cd, Cs, Ce, W, Pb, Bi and U did not show any significant differences at the 95% confidence level, so these elements were rejected for further statistical analysis. Another group of elements (Li, Be, Sc, Co, Ga, Y, Sn, Sb, La, Tl, Th) was removed from the data set because concentrations were close to the limits of detection for many samples. Therefore, the remaining elements (Na, Mg, Al, K, Ca, Ti, V, Mn, Zn, As, Rb, Sr, Mo, Ba) together with ⁸⁷Sr/⁸⁶Sr isotope abundance ratio were considered for principal component analysis (PCA) and linear discriminant analysis (LDA). Finally, LDA was able to classify correctly 100% of cider samples coming from different Spanish regions, France, England and Switzerland when considering Na, Mg, Al, K, Ca, Ti, V, Mn, Zn, As, Rb, Sr, Mo, Ba and ⁸⁷Sr/⁸⁶Sr isotope abundance ratio as original variables.     

Development of porosity in carbons from yeast grains by activation with alkali metal carbonates

Cellular structured activated carbon samples were prepared with the aid of alkali carbonates X2CO3 (X = Li, Na, K, Rb, or Cs) from dry bread yeast with a milling procedure. The resultant carbon possesses a very large adsorption amount even for supercritical methane. The activation with Cs2CO3 gave the greatest surface area of 2420 m2 g(-1) from the subtracting pore effect method. The activation efficiency of X2CO3 (X = Li, Na, K, Rb, and Cs) was associated with the order of Gibbs free energy of X2O (X = Li, Na, K, Rb, and Cs) which should play an important role in the gasification. The carbon activated with Rb2CO3 gave the greatest adsorption amount of supercritical methane of 90 mg g(-1) at 0.9 MPa at 303 K.     

NAA and ICP analysis of obsidian from Central Europe and the Aegean: Source characterisation and provenance determination

INAA and ICPES are compared for their discriminative power in obsidian source characterisation. Geological samples from the Aegean and Carpathian sources were analysed for Na, Sc, Fe, Co, Rb, Sb, Cs, Ba, La, Ce, Sm, Eu, Tb, Yb, Lu, Hf, Ta, Th, U by INAA and for B, Na, Mg, Al, K, Ca, Sc, Ti, Mn, Fe, Zn, Y, Yr, Cs, Ba, La, Ce, Sm, Eu, Gd, Tb, Yb, Lu, Hf by two ICPES procedures. It is shown that all techniques work successfully, however, INAA is more efficient in the chemical discrimination of neighbouring sources.     

Neutron activation analysis of cheese, eggs, fish, fowl and meats

The concentrations of Br, Ca, Cl, Cu, I, K, Mg, Na, Rb, S and Ti in 44 samples of cheese, eggs, fish, fowl and meats sold in Canada were determined with absolute instrumental neutron activation analysis. The procedure is fully computerized and incorporates one short irradiation and counting only. When an element was not detected, its detection limit was calculated. The nuclear interferences and blanks were taken into account. The nutritional significance of the results is discussed.     

Hydrothermal extraction of potassium,sodium, rubidium and cesium from rocks by lithium hydroxide and determination at very low natural levels

The selective extraction of Na, K, Rb and Cs from rocks is described. The method is particularly designed for low levels of rubidium and cesium in basic and ultrabasic rocks. The rocks are decomposed with lithium hydroxide solution at 180°C. Only part of the aluminium and chromium accompany the alkali metals into solution; all other rock constitutents are left behind as insoluble lithium silicate, hydroxides of divalent metals, etc. Concentration of rubidium and cesium too low to be determined directly by flame emission spectrometry are pre-concentrated up to 25-fold by liquid-liquid extraction. Quantitative recovery (>99.5%) of the two metals is achieved by coprecipitation with potassium tetraphenylboron within the organic phase (di-isobutyl ketone) for subsequent back-extraction and dissolution in an acidic aqueous phase. Detection limits are 1 mg kg^?1 Na or K, 0.1 mg kg^?1 Rb and 0.05 mg kg^?1 Cs in the rock for the direct determination and 0.003 mg kg^?1 Rb and 0.001 mg kg^?1 Cs after preconcentration. Methods are described for the purification of lithium hydroxide and the potassium nitrate used as carrier. Results are presented for the Na₂ O, K₂O, Rb and Cs contents and the K/Rb values for 23 geochemical references samples (basic and ultrabasic rocks, and iron formation samples).     

A solid-state 23Na NMR study of monovalent cation binding to double-stranded DNA at low relative humidity

We report a solid-state (23)Na NMR study of monovalent cation (Li(+), Na(+), K(+), Rb(+), Cs(+) and NH(4) (+)) binding to double-stranded calf thymus DNA (CT DNA) at low relative humidity, ca 0-10%. Results from (23)Na--(31)P rotational echo double resonance (REDOR) NMR experiments firmly establish that, at low relative humidity, monovalent cations are directly bound to the phosphate group of CT DNA and are partially dehydrated. On the basis of solid-state (23)Na NMR titration experiments, we obtain quantitative thermodynamic parameters concerning the cation-binding affinity for the phosphate group of CT DNA. The free energy difference (DeltaG degrees ) between M(+) and Na(+) ions is as follows: Li(+) (-1.0 kcal mol(-1)), K(+) (7.2 kcal mol(-1)), NH(4) (+) (1.0 kcal mol(-1)), Rb(+) (4.5 kcal mol(-1)) and Cs(+) (1.5 kcal mol(-1)). These results suggest that, at low relative humidity, the binding affinity of monovalent cations for the phosphate group of CT DNA follows the order: Li(+) > Na(+) > NH(4) (+) > Cs(+) > Rb(+) > K(+). This sequence is drastically different from that observed for CT DNA in solution. This discrepancy is attributed to the different modes of cation binding in dry and wet states of DNA. In the wet state of DNA, cations are fully hydrated. Our results suggest that the free energy balance between direct cation-phosphate contact and dehydration interactions is important. The reported experimental results on relative ion-binding affinity for the DNA backbone may be used for testing theoretical treatment of cation-phosphate interactions in DNA.     

Determination of elements in SRM soil 2709a by neutron activation analysis

A combination of instrumental neutron activation analysis (INAA) and prompt gamma-ray activation analysis (PGAA) was used to value assign 35 elements in SRM soil 2709a (San Joaquin Soil). INAA with counting of short-lived radioisotopes was used for determination of Al, Au, Ca, Dy, K, Mg, Mn, Na, Ti, and V. Elements determined by INAA with counting of intermediate and long-lived radioisotopes included As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Lu, Nd, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Yb, Zn, and Zr. Thermal neutron PGAA was used for the determination of H, B, Si, K, Ti, Mn, Fe, Cd and Gd. Expanded uncertainties were determined for all values reported.     

Capillary electrophoresis of anionic analytes in methanol: effect of counter-ions on electrophoretic mobility

Mobilities of 11 substituted benzoates and 3 nitrophenolates were determined in non-aqueous methanol with Li+, Na+, K+, Rb+, and tetrabutylammonium (Bu4N+) as counter-ions of the background electrolyte. The influence of the ionic concentration of the background electrolyte on the mobility of the analyte anions is more pronounced compared to aqueous solutions. The deviation from the dependence of the mobilities on the ionic strength from the Debye-Hückel-Onsager theory indicates the occurrence of ion-pair formation. For a given ion concentration (10 mmol/L), the decrease of the analyte mobility follows the counter-ion sequence Li+ < Na+ < K+ < Rb+, which is the inverse order of their Stokes radii. Bu4N+ as counter-ion has a similar effect on the analyte mobility than Li+ (which has the same Stokes radius, but a six times smaller crystal radius). Exceptions are some di- and trihydroxybenzoates. The mobilities in methanol and in water with the same counter-ion (Na+) at a given ionic concentration show very low correlation.     

Egyptian and foreign cigarettes

Neutron activation analysis has been employed to determine the concentration of 27 elements in an Egyptian cigarette filter before and after smoking. The filter of three foreign cigarette brands are also analyzed and compared to the Egyptian brand. The elements determined are Al, As, Ba, Br, Ce, Cl, Co, Cr, Cs, Eu, Fe, Hf, K, La, Mg, Mn, Na, Ni, Rb, Sb, Sc, Se, Sr, Th, Ti, V and Zn. It is observed that the concentration of the measured elements in the Egyptian brand are within the concentration range of foreign brands, and that the concentration of As, Br, Cl, K, Na and Se in the filters are increased after smoking regardless the brand examined.     

冠醚配合物的热力学性质的研究 III. 碱金属离子与18C6甲基衍生物配位反应的电导研究

The coordination reaction of Na+, K+, Rb+ and Cs+ with benzo- 15-crown-5, 18-crown-6 and the newly synthesized cyclic polyethers 2, 3-benzo-8, 15-dimethyl-18-crown-6, 2, 3-benzo-8, 11, 15-trimethyl-18-crown-6 in methanol at 25`C has been studied by conductometric titration. The stability constants for the 1:1 coordination compounds were calculated. The marked selectivity of 18-crown-6 toward alkali metal ions was not found in its methyl derivatives. The induction effect of the benzene ring and methyl group on polyether ring reduced the stability of the coordination compounds. In methanol, the stability sequence of te compounds of alkali metal ions with 18-crown-6 was K+>Rb+>Cs+>Na+, that of its dimethyl derivative was K+>Rb+>Na+>Cs+ and that of its trimethyl derivative was K+>Na+>Rb+>Cs+, that is, the methyl substituent had a weaker influence on the stability of Na+ compound than on that of Rb+ or Cs+ compound. In the range of concentration studied, decrease in equivalent conductance is in agreement with the prediction on the basis of the structure of the complexes. The above results may give a clue for modifying the structure of a crown ether for specified selectivity.