Thermal ionization mass spectrometry in the positive or negative ionization mode can be used for precise isotope ratio determinations of most elements. The preferably farmed ions are M+, M-and M0,-(x = 1 4 ) . Recent interesting developments in this field, which are relevant geology, are the U/Th and Re/Os dating methods, re-in determinations of the relative atomic masses of elements by more precise and more accurate isotope ratio measurements, the determination of isotope variations in geological and cosmic samples and the analysis of trace and ultra-trace amounts of elements and elemental species in the environment. In order to measure accurately a low abundant isotope in addition to a high abundant isotope (up to ratios of log), thermal ionization mass spectrometers with deceleration lens systems have been constructed which fulfil the required abundance sensitivities. Chromium (HI)/ chromium(vrj speciation below the pg 1-1 level in different river water samples is reported as an example of the application of positive thermal ionization mass spectrometry in connection with the isotope dilution technique. Rhenium/ osmium determinations in iron meteorites of group IIA and IAB are performed by using a corresponding separation procedure with an OsO4 distillation step and rhenium isolation by anion-exchange chromatography. The isochron for the IIA iron meteorites results in an age of (4.54 k 0.08) X 109 years. These precise measurements also indicate small deviations of the IAB silicate-rich iron meteorite data from the IIA isochron. Precise boron isotope ratio measurements by negative thermal ionization mass spectrometry are applied to determine anthropogenic influences in groundwater samples.

A technique for precise boron isotope ratio measurements with a high detection power has been developed by negative thermal ionization mass spectrometry (NTIMS). Relative standard deviations in the range of 0.03-0.3% have been obtained for the determination of the (11)B/(10)B isotope ratio using nanogram amounts of boron. Ba(OH)(2) has been applied as ionization promoter for the formation of negative thermal ions. By adding MgCl(2) better reproducibilities of the measurement have been achieved. A possible interference of BO(-)(2) ions at mass number 42 by CNO(-) could be excluded by the sample preparation technique used. Contrary to other NTI techniques no dependence of the measured isotope ratio on the boron amount used has been observed. Anthropogenic and natural saline influences in ground water have been successfully identified by boron isotope ratio determinations with this NTIMS method, due to the different isotopic composition of boron in natural and anthropogenic substances. In sewage, the boron isotope ratio is substantially influenced by washing powder, which contains low (11)B/(10)B ratios (expressed in delta(11)B values normalized to the standard reference material NIST SRM 951). In contaminated ground water, low delta(11)B values are normally correlated with high boron and high chloride concentrations. On the other hand, delta(11)B shifts to higher values in less contaminated samples. For ground water with saline influences, only the delta(11)B determination, and not the boron or chloride content, allowed the correct identification of this natural source of contamination.

Aquatris(3‐cyanopentane‐2, 4‐dionato)scandium(III) undergoes two transformations which can be monitored by X‐ray diffraction as well as solid‐state NMR spectroscopy: At 145 K, the mononuclear complex shows a reversible phase transition; in agreement with the symmetry principle, this transition of the t2 type proceeds from the monoclinic room temperature phase to triclinic twins at low temperature, the twin law corresponding to a twofold rotation. Under vacuum at room temperature, the aqua ligand of the complex is irreversibly eliminated and the structure rearranges, forming a 1D chain polymer. In both phases of the mononuclear complex as well as in the polymer, the coordination polyhedra around the ScIII atom represent distorted capped trigonal prisms. Solid‐state 45Sc NMR spectroscopic investigations on powder samples reveal a reversible phase transition of the monoclinic complex at low temperatures. Changes of the NMR signal line shapes for the room and low temperature complex as well as the 1D chain polymer are a fingerprint for different scandium bonding situations.

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The boron isotopic compositions of common synthetic boron products, municipal wastewaters from Switzerland, and three Swiss freshwater lakes were investigated. The δ11B values (δ11B values are normalized to the standard NIST SRM‐951) of synthetic Na‐borates (–0.4 to 7.6‰) and Ca‐Na‐borates (–13.4 to –4.9‰) overlap with those of natural borate minerals and hence suggest that the isotopic signal of anthropogenic boron is not modified during the manufacturing process. As a result it is possible to predict the isotopic composition of synthetic boron products and their potential impact upon contamination of water resources. The δ11B values of municipal wastewaters from two locations in northern Switzerland (–7.7 to –4.5‰) reflect utilization of Na/Ca‐ and/or Ca‐borates depleted in 11B. Freshwater lakes from Switzerland (Lake Zürich, Greifensee, Lake Lugano) yielded a δ11B range of –1.7 to 7.1‰ and boron concentrations of 17 to 102 mg L–1. The boron isotopic ratios decrease with increasing boron concentrations, indicating mixing between anthropogenic boron with a low δ11B signature and meteoric boron with a heavier isotopic signal. We suggest that the isotopic composition of meteoric boron over central Europe has δ11B values in the range of ca. 10 to 20‰, whereas in coastal areas the marine component is larger with a higher 11B/10B ratio (δ11B ∼ 30‰).