ABSTRACT
A method based on laser induced breakdown spectroscopy (LIBS) for monitoring lead and copper accumulation in edible fish, particularly "tilapia del Nilo" (Oreochromis niloticus) is presented. The capability of this analytical method is compared with results obtained by atomic absorption spectrometry. Detection limits by LIBS are 25 parts per million (ppm) for Pb and 100 ppm for Cu, values that are below the maximum permissible levels of some international standards. Application of LIBS detection allows the development of portable instruments for contamination control of edible fish.
Subject(s)
Lasers , Metals/toxicity , Spectrum Analysis/methods , Tilapia/metabolism , Animals , Calibration , Limit of Detection , Muscles/metabolismABSTRACT
We show a new laser-induced breakdown spectroscopy (LIBS) setup based on a small, ultracompact, and low-cost excitation source developed by the authors. The laser is a compact Nd:YAG laser emitting in the multipulse Q-switch regime and is capable of delivering a bunch of pulses with a total energy up to 300 mJ. The developed system is applied to the analysis of Pb and Cu contaminants on fish. LIBS spectra were obtained from scales, muscle, and skin of fresh and frozen samples. The developed excitation source is able to detect 0.25 mg/Kg and 0.20 mg/Kg of Pb and Cu, respectively. In this way, the equipment seems to be adequate to achieve a screening analysis of those contaminants.
Subject(s)
Cichlids/metabolism , Copper/analysis , Food Analysis/instrumentation , Lead/analysis , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/instrumentation , Water Pollutants, Chemical/analysis , Animals , Biological Assay/instrumentation , Equipment Design , Equipment Failure Analysis , Food Contamination/analysis , Lasers , Miniaturization , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
Laser-induced breakdown spectroscopy (LIBS) analysis is applied to study the ablation threshold and the main plasma features of active crystals used for laser processing with Nd(3+) ions. The experiments were conducted by using nanosecond laser pulses from a neodymium-doped yttrium aluminum garnet (Nd : YAG) laser and its harmonics. In particular, we have studied the ablation process in SBN, strontium barium niobate (SrxBa1-xNb2O6, x = 0.6), and SBN, sodium barium niobate (Ba2NaNb5O15), nonlinear and ferroelectric crystals. Two different ablation regimes have been identified by LIBS analysis with high sensitivity compared with the standard method of hole-diameter measurement. Analyzing spectroscopically the plasma emission, we have found a particular behavior with the excitation wavelength. For example, the electronic density and temperature in SBN-generated plasmas present an abnormal behavior with the excitation wavelength. We therefore conclude that the energy gap corresponding to these crystals plays an important role in describing this fact. Hence, the resonant ablation in doped crystals can be a suitable point for exploration in further works in order to use the plasma performances to optimize the laser processing by nanosecond pulses for technological applications.
ABSTRACT
Two of the main items from which to retrieve data in anthropology are teeth and bones. Identification of trace elements in their composition allows valuable information to be obtained about alimentary habits and community life conditions of groups and individuals. Conventional methods used to determine the presence of trace elements require sample preparation, with partial or total destruction of the pieces, which in most cases are unique. In this work we show the possibilities of laser-induced breakdown spectroscopy (LIBS) as a nearly nondestructive tool in anthropology and paleontology for the measurement of the presence and distribution of trace elements in teeth. We applied LIBS to the determination of strontium and magnesium in dentin and enamel of Neolithic, middle age, and modern Homo sapiens teeth. Mg/Ca and Sr/Ca distribution maps of dentin and enamel in modern teeth were created using the data obtained. Ablation threshold fluences of dentin and enamel were also measured using the photoacoustic signal induced by laser ablation. Significant variations were found in the Mg/Ca and Sr/Ca ratios in the tooth dental tissue and between the teeth of the groups and individuals studied. These results can be useful for evolutionary anthropology studies as they can provide information regarding early nutrition, seasonality, and residential mobility.
Subject(s)
Dentin/chemistry , Metals, Alkaline Earth/analysis , Paleodontology/methods , Spectrum Analysis/instrumentation , Spectrum Analysis/methods , Tooth/chemistry , Ablation Techniques , Acoustics , Dental Enamel/chemistry , Equipment Design , HumansABSTRACT
Determination of surface coating composition is a problem of great importance for industry and production related to the quality control of products and processes. One of the most outstanding aspects of laser-induced breakdown spectroscopy (LIBS) is its unique ability to carry out real-time depth profile analysis. This allows, for instance, the identification of layered coatings composition. In this work we performed depth profile analysis using LIBS to determine the composition of layered surface treatments of car bearings. Laser ablation thresholds for each coating layer were determined by acoustic measurements. Transitions between the different coating layers were also identified by an acoustic method. We developed faster and simpler semi-quantitative procedures to determine the relative composition of alloy surface coatings of car bearings as well as the possibility to characterize in real time these treatments.