Laser Ablation Inductively Coupled Plasma Atomic Emission Spectrometry Research Articles

Soda-lime glass trade across the Eurasian Steppe during the 4th to 5th century CE: Evidence from a Xianbei cemetery in Inner Mongolia

A batch of glass beads, including silver-in-glass beads and monochrome beads from the Chenwugou cemetery in Ulanqab, Inner Mongolia, China was analysed using optical microscopy (OM), Scanning Electron Microscopy-Energy Dispersive Spectrometry (SEM-EDS), Laser Ablation Inductively Coupled Plasma Atomic Emission Spectrometry (LA-ICP-AES), and Mass Spectrometry (LA-ICP-MS). Based on their compositions, the silver-in plant ash glass samples are chemically very homogenous and possibly from Iran/Central Asia, if they were not made locally in China. The four monochrome beads are all individually different, with three plant-ash glasses and one natron glass bead thought to be from the southeastern Mediterranean. The silver-in-glass beads were made from a drawn glass tube as the inner layer, with a silver foil on its surface. They were then covered by another glass layer richer in iron oxide, before being cut into beads in a mould.

Application of computed tomography in the analysis of glass beads unearthed in Shanpula cemetery (Khotan), Xinjiang Uyghur Autonomous Region

The glass beads unearthed in sites along the Silk Road usually indicate the communications of arts, business, and cultures between different areas. The production process of glass beads also implies an associated local culture, as well as its provenance. Computed tomography (CT) is a non-destructive three-dimensional method and it has been widely used in the research of various relics. It contributes to discovering and documenting the manufacturing processes for artifacts. Based on the CT images of two glass beads which were unearthed in Khotan, Xinjiang, China, the inner structure and air bubble shapes were investigated. This paper demonstrates how the CT technology contributes to studying the manufacture of archaeological glass beads. Two polychrome beads were analyzed by CT scanning techniques. Bead S-2 is a typical natron glass and bead SC-8 is a soda-lime-silica glass, based on the chemical components analyzed by laser ablation inductively coupled plasma atomic emission spectrometry (LA-ICP-AES). According to computed tomographic analysis, a porous core was covered with a thick layer of glaze. The eye parts from S-2 eye bead were probably made by an embedding technique, which was proved by the 3D shapes of bubbles and the “eyes.” The SC-8 bead was manufactured by a stretching technique which was evidenced by the elliptical bubbles. The yellow stripes wrapped around the glass base present sharp edges in cross section, which seem to reflect grooves carved before the filling process.

Analysis of Some Chinese Potash Glass by Laser Ablation-Inductively Coupled Plasma-Atomic Emission Spectrometry and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry

Laser ablation-inductively coupled plasma-atomic emission spectrometry (LA-ICP-AES) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) were applied to analyze ancient Chinese potash glass. The surfaces of glasses were polished over 100 μm, then pre-ablation was performed to avoid surface weathering effect, and laser ablation was performed in the designed route to eliminate influence of heterogeneity. The glasses were classified into three subgroups by their lime and alumina concentrations, and they may have different recipe and production center. There are various colorants in these glass including metallic copper, and ions of manganese, copper and cobalt. The characteristics of rare earth elements of Chinese potash glass were studied for the first time and it was successfully used to separate the potash glass of Fengmenling and Jiuzhiling. The features of two methods in the studies of ancient glass were discussed.

Laser Defocusing Effects on Laser Ablation Inductively Coupled Plasma-Atomic Emission Spectrometry: Different Ablation Interactions between the Laser and Low-Alloy Steel, Fe Pellets, and a Pond Sediment Pellet

The ablation interaction between a laser and solid samples, which affects the analytical performance for laser ablation inductively coupled plasma atomic emission spectrometry (LA-ICP-AES), was studied. The emission intensities of elements observed by LA-ICP-AES (LA-ICP-AES element signal intensities) for different solid samples were measured under different laser defocusing conditions with a fixed laser output energy. It was found that the optimum laser defocusing conditions were dependent on the different solid samples with different sample characteristics, and also on the different elements with different elemental characteristics in each solid sample. A low-alloy steel, pellets containing different Fe concentrations (0 - 100% Fe pellet), and a pond sediment pellet were used as different solid samples. The variations of the LA-ICP-AES Fe signal intensities observed under different laser defocus conditions were completely different between the low-alloy steel and the pond sediment pellet. The changes in the LA-ICP-AES Fe signal intensities for 90 and 100% Fe pellets were similar to that of the low-alloy steel. However, pellets with lower Fe concentrations (less than 70%) showed different trends and the defocusing behavior became closer to that of the pond sediment pellet. The LA-ICP-AES signal intensities of other elements were also evaluated, and were compared for different solid samples and different defocusing behavior. It was observed that the changes in the LA-ICP-AES signal intensities of almost all elements in the pond sediment pellet showed a similar trend to those of Fe for different laser defocus positions; that is, the elemental fractionation for these elements in the pond sediment pellet seemed to be relatively small. On the contrary, it was found that the LA-ICP-AES Si, Ti, and Zr signal intensities for low-alloy steel showed different trends compared to those of other elements, including Fe, under different defocusing conditions; that is, the elemental fractionation observed for the low-alloy steel was larger than that of the pond sediment pellet. From these results, different ablation interactions between the laser and the different solid samples were considered, and attributed to the sample characteristics, such as the matrix, hardness, and conductivity. Elemental fractionation was attempted to be explained by using elemental characteristics, such as the melting point and ionization energy of the elements.

Studies on laser defocusing effects on laser ablation inductively coupled plasma-atomic emission spectrometry using emission signals from a laser-induced plasma

The effect of laser defocusing on analytical performance of laser ablation inductively coupled plasma atomic emission spectrometry (LA-ICP-AES) was studied by varying laser focus conditions with respect to the surface of a low-alloy steel and a powdered sediment pellet. Laser-induced plasma (LIP) and LA-ICP-AES emission signals and LIP excitation temperatures (LIP T ex) were determined and compared for different laser defocus conditions. LIP Fe and LA-ICP-AES Fe emission signals and LIP T ex decreased when the laser was defocused for the low-alloy steel. On the other hand, when the sediment pellet was ablated, LIP T ex decreased when the laser was defocused. However, LA-ICP-AES Fe emission signals increased at first, then decreased when the laser was defocused more. It was concluded that LIP T ex and LIP and LA-ICP-AES Fe emission signals are dependent on laser shot conditions (focus–defocus), and are also dependent on sample type (texture, mineralogy, hardness, conductivity and heat capacity).

Determination of elements in agricultural soils using IR laser ablation inductively coupled plasma atomic emission spectrometry

Direct sampling of soil samples was studied using laser ablation inductively coupled plasma atomic emission spectrometry (LA-ICP-AES). Samples were pressed into pellets together with a binder and an internal standard. The amount of ablated material for pellets with various binding materials was evaluated. Silver and aluminium powders were found as adequate binders for the pellet preparation. Optimisation of laser parameters, and sample displacement during interaction have been performed. Moderate laser pulse energy of 150 mJ together with a 20-Hz repetition rate was found to be the most suitable to obtain stable analytical signal. Sample displacement leads to more precise sampling and long time signal plateau that can be measured even with sequential spectrometers. Precision was approximately 5% for most of the elements studied. Calibration was performed using soil samples spiked with solutions. Internal standards improved correlation coefficients for calibration, which were at least 0.98. Germanium powder was the most efficient internal standard. Certified reference soils were analysed with an accuracy better than 10%.

Analysis of tungsten carbide coatings by UV laser ablation inductively coupled plasma atomic emission spectrometry

Tungsten carbide coatings (thickness 0.1–0.2 mm) containing 8.0, 12.2, 17.2 and 22.9% Co were studied with laser ablation inductively coupled plasma atomic emission spectrometry (LA-ICP-AES). Composition of these plasma sprayed deposits on steel disks was determined using X-ray fluorescence spectrometry and electron microprobe energy/wavelength dispersive X-ray spectrometry. The coatings were ablated by means of a Q-switched Nd:YAG laser at 266 nm (10 Hz, 10 mJ per shot) coupled to an ICP echelle-based spectrometer equipped with a segmented charge-coupled device detector. Non-linear dependences of cobalt lines intensities on the Co percentage were observed both at a single spot ablation and at a sample translation. This behaviour could be attributed to a complex phase composition of the system W–C–Co. However, employing tungsten as internal standard the linear calibration was obtained for studied analytical lines Co II 228.616 nm, Co II 230.786 nm, Co II 236.379 nm and Co II 238.892 nm.

Use of a single calibration graph for the determination of major elements in geological materials by laser ablation inductively coupled plasma atomic emission spectrometry with added internal standards

The possibility of internal standardisation in laser ablation inductively coupled plasma atomic emission spectrometry (LA-ICP-AES) of geological materials by added Sc2O3 and Y2O3 has been examined to cover the wide range of concentrations of major and minor constituents both in silicate rocks and limestones. A Nd:YAG laser (355 nm, 10 Hz, 10 mJ per shot) was used for the ablation of discs obtained by fusion of the mixture of samples and oxides of Sc and Y with lithium tetraborate. The flux/sample ratio was in the range from 6 to 10. The contents of analytes were within the concentration range from hundredths to tens of percentage. The trace elements copper and nickel were studied, too. An ICP emission spectrometer OPTIMA 3000 DV was used for the measurement of Si, Al, Ca, Mg, Sr, Ba. Fe, Ti, Mn, Ni, Cu. Na and K analyte lines and Y and Sc reference lines in the axial observation mode. The long-term and the short-term repeatability of measurement were improved by employing scandium or yttrium internal references lines for the above analytes from 6% to 1.5% of RSD and from 2.4% to 1.0% of RSD, respectively. The correlation of signals with concentrations was improved in terms of the correlation coefficient r from 0.90-0.97 to 0.98-0.998 and the relative uncertainty on the centroid of concentrations was improved 2-3 times. A single calibration graph covering the concentration range both in silicates and carbonates is possible for each of elements. as the matrix effects are compensated for by internal standards and the excess of Li2B4O7.

Laser ablation of synthetic geological powders using ICP-AES detection: effects of the matrix, chemical form of the analyte and laser wavelength

A systematic study of the influence of the physical and chemical properties of analogues of geological samples and of laser wavelength on laser ablation was conducted. Different chemical forms of several test elements were investigated, first as pure elements, then mixed in various matrices. Synthetic model samples were prepared from different crystalline compounds of Mg, Al and Fe spiked in SiO 2 or CaCO 3 and manufactured in the form of pressed pellets that were analysed by laser ablation inductively coupled plasma atomic emission spectrometry (LA-ICP-AES). This study was performed at two laser wavelengths (1064 and 266 nm) with a Nd:YAG laser and using ICP-AES as an elemental detector. These various steps made it possible to demonstrate that the LA-ICP-AES response factors of the analytes are strongly dependent on their chemical form and on the bulk composition of the matrix. These effects were also found to be laser wavelength dependent and the use of a UV laser did not lead to any improvements to minimise these effects. In contrast, there was no influence of the grain size or binding pressure of the pressed pellets. However, normalisation to a matrix element could compensate for differences in the response factors of the analytes. Implications for direct quantitative elemental analysis of geological materials by laser ablation related techniques are that calibration without matching in terms of the mineralogical and chemical composition of the matrix and of the chemical forms of the analytes can lead to systematic errors in the determination of the element concentration.

Depth Profiling of Thick Layers of Graded Metal—Zirconia Ceramic Coatings Using Laser Ablation Inductively Coupled Plasma Atomic Emission Spectrometry

The feasibility of depth profiling of thick layers (>100 μm) consisting of partially stabilized zirconia coating and graded metal—ceramic coating on Inconel steel (ZrO2–Y2O3/NiCrAlY/steel and ZrO2–CeO2/NiCrAlY/steel) was studied on the basis of the use of laser ablation inductively coupled plasma atomic emission spectrometry (LA-ICP-AES). An ICP spectrometer equipped with a multichannel detection was used for the simultaneous measurements of the line intensities. The ablation was performed with a Nd:YAG laser operated in a Q-switched mode at 266 nm. To study the erosion rate, we used either a static or a translation mode for the ablation, and the corresponding temporal behavior of the signals was studied. A higher erosion rate was found for the translation mode when depths higher than several hundred micrometers were probed.

Determination of Zr and Ti in 3-μm-Thick ZrTiN Ceramic Coating Using Laser Ablation Inductively Coupled Plasma Atomic Emission Spectrometry

Analysis of 3-μm-thick ZrN, TiN, and ZrTiN ceramic coatings on a high-speed steel substrate by laser ablation inductively coupled plasma atomic emission spectrometry (LA-ICP-AES) is described. A Nd:YAG laser was used in the Q-switched mode and operated at 355 nm and 5 mJ. Ablation patterns were obtained on the target surface by moving the ablation chamber with respect to the laser beam by means of an X-Y translator. Control of the depth of penetration was obtained by successively performing a limited number of cycles. Transient signals were obtained and their peak areas were used for the construction of calibration graphs based on the concentrations determined by energy-dispersive X-ray (EDX) analysis. An erosion rate of 0.1 μm per cycle was observed. Crater shape and depth, temporal behavior, and reproducibility of the signals are described.

Determination of additives in PVC material by UV laser ablation inductively coupled plasma atomic emission spectrometry

UV laser ablation inductively coupled plasma atomic emission spectrometry (LA-ICP-AES) has been applied to the direct determination of additives in solid poly(vinyl chloride) materials. A Nd:YAG laser, operating at its fourth harmonic (266 nm), was used with a beam masking device, in the most reproducible conditions, to introduce solid particles into the plasma torch of a simultaneous ICP-AES system. Emphasis was placed on both precision and accuracy in the analysis of PVC materials by LA-ICP-AES. A series of six in-house PVC reference materials was prepared by incorporating several additives in increasing concentrations. Three alternative methods were evaluated to certify the amount of incorporated elements: ICP-AES with sample dissolution, NAA and XRF. Satisfactory results and good agreement were obtained for seven elements (Al, Ca, Cd, Mg, Sb, Sn and Ti) among the ten incorporated. Sample homogeneity appeared to be satisfactory, and calibration graphs obtained by LA-ICP-AES for several elements are presented. Finally, the performance of the technique in terms of repeatability (1.6-5%), reproducibility (2–5%), and limits of detection was investigated.

Selection of internal standards for analysis of silicate rocks and limestones by laser ablation inductively coupled plasma atomic emission spectrometry (LA-ICP-AES).

Included (Si, Ca) and added (Li, B) internal standards (IS) have been used comparatively in LA-ICP-AES of silicates and limestones to improve both precision and accuracy. A Q-switched Nd:YAG laser (355 nm, 10 Hz, 10 mJ per shot) has been applied for ablation. Samples have been prepared by fusion with Li(2)B(4)O(7) and measured using a Perkin-Elmer Optima 3000 ICP system. Both types of IS have given a relative standard deviation (RSD) less than 2-1%, which improved the repeatability by a factor of 2-10 and calibration graphs have been linear over the whole concentration range.

Determination of elements in polymers by laser ablation inductively coupled plasma atomic emission spectrometry: effect of the laser beam wavelength, energy and masking on the ablation threshold and efficiency

The application of laser ablation inductively coupled plasma atomic emission spectrometry (LA-ICP-AES) to the direct determination of solid inorganic additives in polymeric materials has been studied. The use of a Nd:YAG laser, operating at both infrared (IR) (1064 nm) and ultraviolet (UV) (355 and 266 nm) wavelengths, has been investigated for poly(vinylidene fluoride) (PVDF), poly(vinyl chloride) (PVC) and poly(ethylene) (PE) materials. In order to obtain reliable ablation conditions, emphasis was placed on the control of the experimental parameters and the understanding of the laser-surface interaction characteristics. It has been shown that, at low energies, a threshold process characterized by the swelling of the surface takes place, accounting for the rims surrounding the craters. This threshold was dependent not only on the energy, but also on the laser wavelength. In order to eliminate the formation of the swelling and to find the most reproducible conditions, it has been shown that the use of UV laser radiation and beam masking offer a better control of the laser ablation process, leading to a satisfactory relative standard deviation on both the estimated ablated mass (6.4%) and the emission signal obtained by ICP-AES (in the 2%–5% range). It has also been established that the optimum laser energy is in the frame of 6 mJ (10 J cm −2) to 10 mJ (14 J cm −2) at 266 nm. Erosion rate, linearity of the ablated mass against time for PVDF, PVC and PE, and a titanium calibration graph obtained for a PVC matrix are then briefly discussed and illustrate the technique's analytical potential.

Aerosol Mass Measurement and Solution Standard Additions for Quantitation in Laser Ablation-Inductively Coupled Plasma Atomic Emission Spectrometry

A new approach for quantitation in laser ablation-inductively coupled plasma atomic emission spectrometry (LA-ICPAES) is presented. A portion of the laser-ablated sample aerosol is diverted to an aerosol mass monitor to measure variations in the amount of sample ablated and transported to the ICP torch. This provides a normalization for variations in laser ablation efficiency due to changes in laser power and focus at the sample and variations in material transport out of the ablation cell and into the ICP torch. During the laser ablation sampling process, solution standards are nebulized and the aerosol is added to the laser-ablated aerosol to generate a standard addition curve for the analyte being determined. The standard addition procedure corrects for potential plasma-related matrix effects in the ICP emission signal resulting from the ablated sample. The precision of this method, for triplicate analyses for the determination of 16 elements in four glass samples, and the accuracy of this method relative to the nominal glass compositions are both approximately 10%. 19 refs., 4 figs., 4 tabs.

In situ determination of uranium in soil by laser ablation-inductively coupled plasma atomic emission spectrometry

The concentration of uranium in soil has been determined for 80 sites in an area suspected to have uranium contamination by in situ laser ablation - inductively coupled plasma atomic emission spectrometry (LA-ICPAES), utilizing a field-deployable mobile analytical laboratory. For 15 of the 80 sites analyzed, soil samples are collected so that the field LA-ICPAES results could be compared to laboratory-determined values. Uranium concentrations determined in the field by LA-ICPAES for these 15 sites range from <20 parts per million (ppm) by weight to 285 ppm. The uncertainty in the values determined, however, is large relative to the uranium concentrations encountered at this site. The 95% confidence interval (CI) values are approximately 85 ppm. The uranium concentrations determined by laboratory LA-ICPAES analysis range from <20 to 102 ppm (95% CI of approximately 50 ppm); microwave dissolution and subsequent standard addition determination of uranium by solution nebulization ICPAES using an ultrasonic nebulizer yields 19-124 ppm uranium (95% CI of approximately 10 ppm). For 11 of the 15 samples, the field- and laboratory-determined uranium concentrations agree, within the uncertainty of the determined values. 19 refs., 5 figs., 3 tabs.