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This study uses conventional 87Sr/86Sr and 143Nd/144Nd isotope and interelement ratios of Ca, Sr, K, Mn, Mg and Ti as fingerprints for provenancing ordinary Portland cements (OPC). Herein, the first database of Sr and Nd isotope ratios investigated in OPCs, stemming from 29 cement plants located worldwide, was created. The results show that the Sr isotope ratios of OPCs are higher than those of seawater from the observed geological period. The spread of 143Nd/144Nd in OPCs is not as large as the spread for 87Sr/86Sr isotope ratios. However, the combination of both Sr and Nd isotope ratios provides the potential for distinguishing between cements of different production sites. Most of the OPCs investigated have measurable differences in their 87Sr/86Sr and 143Nd/144Nd isotope ratios, which can be employed as a valuable analytical fingerprinting tool. In the case of equivocal results, divisive hierarchical clustering was employed to help overcome this issue. The construction of geochemical profiles allowed the computing of suitably defined distances between cements and clustering them according to their chemical similarity. By applying this methodology, successful fingerprinting was achieved in 27 out of the 29 ordinary Portland cements that were analysed.
Growing awareness of the impact of monoterpenes on climate, atmospheric chemistry, and indoor air quality has necessitated the development of measurement standards to globally monitor and control their emissions. For National Metrology Institutes to develop such standards, it is essential that they demonstrate measurement equivalence for assigned values at the highest levels of accuracy. This report describes the results of a pilot comparison for 4 key monoterpene species: α-pinene, 3-carene, R-limonene and 1,8-cineole, at a nominal amount-of-substance fraction of 2.5 nmol mol-1. The objective of this comparison is to evaluate participant capabilities to measure trace-level monoterpenes using their own calibration techniques.