Cited By 26International audienceThe needs of the petroleum industry in studies dedicated to trace metals determination are highly related to exploration, but also to exploitation activities for corrective actions during oil production and refining. Two techniques provide a very large concentration range of metal compounds to be determined on a routine basis, ICP-OES being preferred for major element analysis whereas ICP-MS is particularly convenient for ultra trace metals analysis. Direct introduction of petroleum product in the plasma require a methodical approach in order to minimise matrix effect. Here, three different sample introduction modes have been investigated depending on the elements of interest and the matrix analysed. A classical pneumatic nebulizer and an ultrasonic nebulizer (USN) were compared for ICP-OES. These introduction modes were compared with a microflow pneumatic concentric nebulizer associated with a chilled spray chamber used with ICP-MS. Classical pneumatic nebulisation with ICP-OES leads to ppm range limit of quantification in the petroleum product and five times higher with gasoline due to important dilution factor. The use of an USN coupled with ICP-OES reduce limit of quantification in gasoline to the 50 ppb range, but further study of matrix effects with such an introduction must be done. The PFA-100 associated with a cooled Scott chamber used with ICP-MS reduce also limit of quantification in the petroleum product to the 10 ppb range for most elements. The initial important dilution factor allows the introduction of light matrices without further dilution, but require anyhow the use of a standard addition method, which is time-consuming. Then, the choice of a technique is definitively dependant on the needs required by the laboratory between high throughput analyses and very low limit of quantification. Copyright © 2007, Institut français du pétrole

The chemical speciation, fractionation and availability of mercury in sediments from a cinnabar mining area (Almadén, Spain) was studied with different extraction and analytical procedures, in order to determine the degree to which the ecosystem is harmed by this pollutant. Three total extraction procedures, a sequential extraction and the speciation of organo-mercury compounds were performed in nine sediment samples. In the study area, although concentrations of mercury can be extremely high (up to 1000 mg kg⁻¹), no organo-mercury compounds were detected (<2 µg kg⁻¹) and the availability of this element seems restricted. One of the methods for total extraction presented considerably lower recovery in Almadén's sediments, yet the results were controlled with certified reference materials. This disagreement was attributed to the fact that the mercury is in a refractory form. Sequential extraction was able to show that most of the mercury is associated with sulfides (probably as metacinnabar) or in the residual refractory phase (probably as red cinnabar).

The rapid and precise determination of tributyltin (TBT) in sediments and biological tissues has been performed by species specific isotope dilution mass spectrometric analysis (IDMS) using an inductively coupled plasma mass spectrometer as detector after capillary gas chromatography (CGC-ICP-MS). A new labelled TBT standard (¹¹⁷TBTCl in methanolic solution) commercial isotope provided by LGC Limited (Teddington, UK) was used for these determinations. Parameters affecting the ICP-MS performances, such as correction for detector dead time and mass bias correction, were carefully studied. The mass bias was corrected using two different methods: the bracketing mode and an on-line mode based on a continuous nebulisation of an antimony solution (¹²¹Sb and ¹²³Sb). The on-line mode has been successfully applied for mass bias corrections and allows simultaneous GC-ICP-MS analysis of organotins. Three spiking procedures were compared using isotopically enriched TBT (¹¹⁷TBT) to compare the efficiency of the extraction procedures for the different samples studied. A rapid method was developed (2 min) giving yield to good precision (uncertainty range between 0.7 and 13.7%) using a simultaneous microwave extraction and spiking procedure. The accuracy and precision of the different protocols has been validated on certified reference materials, such as PACS 2 (980 ng Sn g⁻¹) and CRM 462 (70 ng Sn g⁻¹) for the sediments, CRM 477 (2200 ng TBT g⁻¹) and CRM 710 (135.1 ng TBT g⁻¹) for the biological tissues. The results obtained were in all cases in good agreement with the certified reference values.

The olive oil industry is subject to significant fraudulent practices that can lead to serious economic implications and even affect consumer health. Therefore, many analytical strategies have been developed for olive oil’s geographic authentication, including multi-elemental and isotopic analyses. In the first part of this review, the range of multi-elemental concentrations recorded in olive oil from the main olive oil-producing countries is discussed. The compiled data from the literature indicates that the concentrations of elements are in comparable ranges overall. They can be classified into three categories, with (1) Rb and Pb well below 1 µg kg⁻¹; (2) elements such as As, B, Mn, Ni, and Sr ranging on average between 10 and 100 µg kg⁻¹; and (3) elements including Cr, Fe, and Ca ranging between 100 to 10,000 µg kg⁻¹. Various sample preparations, detection techniques, and statistical data treatments were reviewed and discussed. Results obtained through the selected analytical approaches have demonstrated a strong correlation between the multi-elemental composition of the oil and that of the soil in which the plant grew. The review next focused on the limits of olive oil authentication using the multi-elemental composition method. Finally, different methods based on isotopic signatures were compiled and critically assessed. Stable isotopes of light elements have provided acceptable segregation of oils from different origins for years already. More recently, the determination of stable isotopes of strontium has proven to be a reliable tool in determining the geographical origin of food products. The ratio ⁸⁷Sr/⁸⁶Sr is stable over time and directly related to soil geology; it merits further study and is likely to become part of the standard tool kit for olive oil origin determination, along with a combination of different isotopic approaches and multi-elemental composition.