Analytical Chemistry in Israel

Abstract

Analytical chemistry in Israel is not in as good a shape as one may wish. Several attempts have been made to instill interest in this branch of the profession among faculty members, practicing chemists and students, but no great stride forward can be recorded, and on the contrary, some set-backs must be noted. Nevertheless, analytical chemistry is practiced vigorously in several laboratories, and original Israeli contributions in this field have been noted by the international community of analytical chemists. It is on this background that the present survey is being presented.     

67~(th) Meeting of the Israel Chemical Society

Topics: Charge- Transfer Reactions, Nanochemistry and Single Molecules, Stereochemistry andAssymmetric Synthesis, Bioinorganic and Bioorganic Chemistry, Enzymes and Proteins, Quantum Chemistry, Chemistry Education, Thin Films and Supramolecular Chemistry, Colloid Chemistry, Recent Israeli Scientific Contributions, Analytical Chemistry, Industrial Chemistry and more.The conference will take place onJanuary 29-30, 2002At the Renaissance Hotel and Convention Center, Jerusalem, Isra…     

Neutron activation analysis for determination of trace elements in sediments in the Sea of Galilee,Israel

The feasibility of applying both thermal and epithermal neutron activation analysis for simultaneous determinations of elemental composition in sediments, collected from the Sea of Galilee (Kineret Lake), Israel, during 1988–1993, was experimentally investigated. In the present work, the concentrations of 30 elements (Al, Ba, Br, Ca, Ce, Co, Cs, Cr, Eu, Fe, Hf, K, La, Lu, Mg, Mn, Na, Nd, Rb, Sc, Si, Sr, Ta, Tb, Th, Ti, U, V, Yb and Zn) in sediments were determined. The validity of the method was checked by analyzing the U.S. NBS Standard Reference Material SRM-1633a; the elemental content found agreed well with the published certified data. Aluminium was determined by reactor neutron activation analysis (RNAA) taking into account the contribution of silicon to the total²⁸Al activity by the²⁸Si(n,p)²⁸Al reaction. Measurements of irradiated mixtures of Si and Al showed that the dependence of log SiAl mass ratio vs. log cadmium ratio (R _Cd) of²⁸Al is almost linear. The data can be analyzed more accurately by a parabolic correlation (log Si:Al mass ratio vs logR _Cd). The concentrations of fission radionuclide¹³⁷Cs, an activation radionuclide¹³⁴Cs (derived from Chernobyl accident) and the naturally occuring radionuclides⁴⁰K,²²⁶Ra and²³²Th in sediments were also measured by -ray spectrometry using Marinelli (Reentrant) Beaker-Sample Containers.     

Determination of trace amounts of gold in the presence of rare earth elements in rock samples from Makhtesh Ramon (Southern Israel), by instrumental epithermal neutron activation analysis

Epithermal neutron activation analysis (ENAA), followed by high resolution gamma-ray spectrometry, was applied to determine trace amounts of Au in the presence of rare earth elements (REE) from vein samples in the basaltic rocks of Makhtesh Ramon, located in southern Israel. The contribution of¹⁵²Eu (411.1 KeV) to the 411.8 keV peak of¹⁹⁸Au was determined using multiple gamma-peak, ratios derived from Eu standards and mixtures of Au and Eu. The concentration of Au was found to be in the range of 10–80 ppb. A group of rare earth elements: La, Eu, Ce, Tb, Sm, Lu, Yb was identified; the concentration of Eu was found to be 0.5 ppm.     

Micropeptins from Microcystis aeruginosa collected in Dalton reservoir, Israel

Three new micropeptins, micropeptin DR1056, DR1060 and DR1006 and three known metabolites, micropeptin SF909, aeruginosins 298A and B were isolated from the extracts of a Microcystis aeruginosa bloom material collected in Dalton reservoir, Israel. The planar structure of the compounds was determined by homonuclear and inverse-heteronuclear 2D NMR techniques as well as high-resolution mass spectrometry. The absolute configuration of the asymmetric centers of the amino acids was studied using Marfey’s method for HPLC. The inhibitory activity of the compounds was determined for the serine proteases: trypsin, chymotrypsin, and elastase and for amino peptidase N.     

Micropeptins from Microcystis sp. collected in Kabul Reservoir,Israel

Three new micropeptins, micropeptin KR1030, KR1002 and KR998 and the known microcyclamide GL546A were isolated from the extract of Microcystis sp. bloom material collected in Kabul Reservoir, Israel. The planar structures of the compounds were determined by homonuclear and inverse-heteronuclear 2D-NMR techniques as well as high-resolution mass spectrometry. The absolute configuration of the asymmetric centres of the amino acids was studied using Marfey's method for HPLC. The inhibitory activity of the compounds was determined for the serine proteases: trypsin, chymotrypsin and elastase.     

The firing temperature of a persian-period pottery kiln at Tel Michal,Israel, estimated from the composition of its pottery

The firing temperature of a Persian-period kiln excavated at Tel Michal (Makmish), on the Mediterranean coast north of Tel Aviv, Israel, is estimated from the composition of its pottery, using X-ray diffraction and IR spectroscopy methods. The kiln was built with two chambers: an upper one where the vessels were fired and a lower one for the burning. Storage jars that had been fired and remained inside the kiln are composed of lime tempers and quartz sand in a fired clay matrix that contains amorphous material and the high-temperature Ca-silicates gehlenite and anorthite. The tempers are composed of re-formed calcite. Thermal simulation indicates that the composition is compatible with a heating temperature of 800–900°C, which represents the firing temperature in the upper chamber of the kiln. Dedicated to Professor Lisa Heller-Kallai on the occasion of her 65^th birthday     

XRF study of archaeological and metallurgical material from an ancient copper-smelting site near Ein-Yahav, Israel

A movable XRF instrument (a bench-top designed machine modified to work in the field for archaeological purposes) was used for analysis of artifacts and sediments during the field study (01–07 April 2003) of a small copper-smelting site in the Negev (about 30 km west of the Feinan complex of ancient copper mines and smelting sites in Jordan). The site consists of a relatively small hill with blackened slopes, covered mainly by crushed copper slag. The surface collection of datable objects (i.e. pottery shards and stone tools) indicated that the site had functioned at the end of the Early Bronze Age and during the Roman/Byzantine time.

The analysis of Cu concentration in the ash and in the ground as well as the analysis of ore and slag, were used as markers for the identification of the operation centers and for locating the remains of the smelting devices used at the end of the Early Bronze Age for smelting copper. The ore in use typically contained 35–45% Cu, up to 1% Mn and up to several percent Fe. The slag contained 13–20% Mn and 1–5% Cu and Fe. From these results we are able to estimate the Cu production scale during the first and most active period on this site, at the end of the Early Bronze Age.