Laser ablation GC–MS analysis of oil-bearing fluid inclusions in petroleum reservoir rocks

The recently developed technique of ultraviolet femtosecond laser ablation inductively coupled plasma mass spectrometry (UV-fs-LA-ICP-MS) combined with a freezing cell is expected to improve the analysis of CO2-rich fluid inclusions by decreasing their internal pressure and avoiding the common problem of uncontrolled explosive fluid release on ablation. Here, we report the application of this technique through the case study of CO2-rich fluid inclusions from the quartz vein-style Au-Mo deposit of Dahu in the Xiaoqinling region of central China. The concentrations of Li, B, Na, Al, K, Ca, Mn, Fe, Cu, Zn, Rb, Sr, Mo, Ag, Te, Cs, Ba, Au, Pb, and Bi were analyzed in 124 (not all for Al and Ca) fluid inclusions, which have low to moderate salinity and multiphase composition (liquid H2O + liquid CO2 ± vapor CO2 ± solids). The Dahu fluids are dominated by Na and K. The concentrations of Mo are always below the detection limit from 0.005 to 2 ppm (excluding values obtained from fluid inclusions with accidentally trapped solids). The Dahu ore fluids differ from metamorphic fluids in compositions and most likely represent two separate pulses of spent fluids evolved from an unexposed and oxidized magmatic system. The UV-fs-LA-ICP-MS analysis of fluid inclusions in a frozen state improves the overpressure problem of CO2-rich fluid inclusions during laser ablation. The transformation of gaseous and liquid CO2 into the solid state leads to a significant decline in the internal pressure of the fluid inclusions, while femtosecond laser pulses generate a minimal heat input in the sample and thus maintain the frozen state during ablation. Transient signals of CO2-rich fluid inclusions obtained in this study typically had one or multiple peaks lasting for more than 15 seconds, without an initial short signal spike as obtained by ns-LA-ICP-MS analysis of CO2-rich fluid inclusions at room temperature.

Download Full-text

The individual analysis of fluid inclusions in minerals using Laser Ablation Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS): an evaluation

Geologica Belgica ◽

10.20341/gb.2014.030 ◽

2001 ◽

Vol 3 (3-4) ◽

pp. 215-230

Author(s):

Wouter HEIJLEN ◽

Philippe MUCHEZ

Keyword(s):

Mass Spectrometry ◽

Laser Ablation ◽

Fluid Inclusions ◽

Inductively Coupled Plasma ◽

Internal Standard ◽

Natural Quartz ◽

Inductively Coupled ◽

Ms Analysis ◽

Icp Ms ◽

Plasma Mass Spectrometry

During the last decade, the possible application of laser ablation inductively coupled plasma - mass spectrometry (LA-ICP-MS) as a quantitative technique for the analysis of individual fluid inclusions has been intensely studied. The quantitative ability of this technique is, however, complicated by several fractionation processes that operate during ablation, transport and analysis in the ICP-MS. In the present study, a number of these fractionation effects were studied and the quantitative ability of LA-ICP-MS analysis of fluid inclusions in natural quartz is evaluated. Using NIST SRM 612 and 614 as reference materials, it is shown that the fractionation during transport is minimised when the sample cell is flushed with He, in contrast with the set-up where Ar is used. Calcium has been successfully applied as an internal standard to calibrate the REE in NIST-glasses. The use of Ca to calibrate other lithophile and chalcophile elements, such as K, Zn, Cu and Pb, can however be questioned. It is shown that the technique is capable of semi-quantitatively characterising different fluid inclusion populations in natural quartz, which demonstrates its importance as a tool for palaeofluidflow modelling. However, during LA-ICP-MS analysis of fluid inclusions in natural quartz, elements are reprecipitated in a glassy phase, as shown by SEM-EDX analysis of the sample surface after ablation. This process could result in a fractionation and may account for the poor precision of the analysis.

Download Full-text

Quantitative Determination of the Surface Distribution of Supported Metal Nanoparticles: A Laser Ablation–ICP–MS Based Approach

Chemosensors ◽

10.3390/chemosensors9040077 ◽

2021 ◽

Vol 9 (4) ◽

pp. 77

Author(s):

Davide Spanu ◽

Gilberto Binda ◽

Marcello Marelli ◽

Laura Rampazzi ◽

Sandro Recchia ◽

...

Keyword(s):

Spatial Distribution ◽

Laser Ablation ◽

Quantitative Determination ◽

Metal Nanoparticles ◽

Total Mass ◽

Functional Materials ◽

Metal Extraction ◽

Ms Analysis ◽

Icp Ms

A laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) based method is proposed for the quantitative determination of the spatial distribution of metal nanoparticles (NPs) supported on planar substrates. The surface is sampled using tailored ablation patterns and the data are used to define three-dimensional functions describing the spatial distribution of NPs. The volume integrals of such interpolated surfaces are calibrated to obtain the mass distribution of Ag NPs by correlation with the total mass of metal as determined by metal extraction and ICP–MS analysis. Once this mass calibration is carried out on a sacrificial sample, quantifications can be performed over multiple samples by a simple micro-destructive LA–ICP–MS analysis without requiring the extraction/dissolution of metal NPs. The proposed approach is here tested using a model sample consisting of a low-density polyethylene (LDPE) disk decorated with silver NPs, achieving high spatial resolution over cm2-sized samples and very high sensitivity. The developed method is accordingly a useful analytical tool for applications requiring both the total mass and the spatial distribution of metal NPs to be determined without damaging the sample surface (e.g., composite functional materials and NPs, decorated catalysts or electrodic materials).

Download Full-text