This study evaluates laser-induced breakdown spectroscopy (LIBS) as a screening and imaging technique for detecting, localizing, and preliminarily identifying plastic particles in cave sediments. A spectral database of selected polymer standards was established and processed using a custom fingerprint-based algorithm that calculates similarity scores based on the Manhattan distance. The workflow was first evaluated using bulk polymer standards, with pairwise comparisons confirming material-specific spectral patterns and demonstrating the ability of LIBS to discriminate among different polymer types. The approach was then applied to spiked cave sediment pellets containing polypropylene (PP) at defined concentrations and to mixed-polymer systems consisting of PP and either polyvinyl chloride (PVC) or polytetrafluoroethylene (PTFE). LIBS imaging revealed discrete polymer-rich regions within the sediment matrix that corresponded to individual plastic particles or fragments and showed a concentration-dependent increase in PP-associated signal. Finally, the workflow was applied to plastic fragments collected from Bull Rock Cave. A LIBS-based comparison enabled rapid preliminary classification of the unknown particles, while a Fourier-transform infrared (FTIR) spectroscopy analysis confirmed the presence of PP in both samples. These results demonstrate that LIBS can rapidly locate suspected plastic particles within heterogeneous sediments, allowing confirmatory FTIR or Raman analysis to be targeted only to selected regions.

The nickel and zinc contamination of algae on a cellulose filter was studied with double pulse 1064-1064 nm laser-induced breakdown spectroscopy (LIBS). Samples of the green alga Desmodesmus subspicatus were contaminated with zinc and nickel. The surface concentrations on the filter calculated from the reference Inductively Coupled Plasma Mass Spectrometry analysis were 25 and 64 ng cm-2 for nickel and zinc respectively. The algae are resting on the filter after drying and a double adhesive tape was used to fix the sample on the microscopic glass. During optimization method a compromise of 23-30 mJ pulse energies were set for maintaining a detectable or highest signal intensity of the analyte and not destroying the filter. Best conditions for maximum analyte signal and minimum deviation between the spectral behaviour of the analyte and the compared line of Na I, K I, Mg I, Mg II, Mn I, Mn II, Ca I, Ca II, and C I was 700 ns gate delay and 0 s interpulse delay. The deviation was rather more influenced with the signal-to-noise ratio of the analyte line than the closeness of the upper-level energies of the compared lines. The filter without algae showed systematically lower electron number density and total emissivity by units of percents than the filter with algae.

The aim of this study was to determine whether the degree of pulse overlap affects the analytical response of LA-ICP-MS when utilized in scanning mode. The investigation focused not only on the analytical signal but also on the properties of the generated aerosol and the morphology of ablation craters. Ablation was carried out using a nanosecond ablation system on single-element samples of metals and metalloids, specifically Cr, Hf, Sb, Si, Ta, and W. Pure single-element standards were selected to eliminate elemental fractionation and ensure the chemical composition of the generated aerosol was consistent across all particle sizes. The effect was studied on the surfaces of the samples prepared in various ways, including polished and two types of roughened finishes. It was found that the degree of laser pulse overlap significantly influences the quantity of generated particles, their size, and consequently the measured analytical signal, altering it by tens of percent. Slightly different properties were observed in the groups of metal and metalloid samples. For metals, an increasing overlap of pulses resulted in a decrease in the analytical signal across all types of surfaces. For metalloids, the results were different on polished surfaces. The study shows that adjusting the pulse overlap by combining the scan speed and laser repetition rate can have a significant effect on the LA-ICP-MS analysis results.

The chromium and copper contamination of algae on a filter was directly monitored with laser-induced breakdown spectroscopy (LIBS) as a demonstration of LIBS capabilities. Liquid samples of the green alga Desmodesmus subspicatus were intentionally contaminated with chromium, incubated, filtered, and the filters with the algae were analysed. Inductively coupled plasma mass spectrometry (ICP-MS) was used as a reference method. One half of the filter with the algae was dissolved and analysed as a solution with ICP-MS and the second half was subjected to the LIBS and laser ablation-ICP-MS analysis. Chromium and copper were attributable to the algae contamination and detectable with LIBS. The results from the LIBS provided almost equivalent information about the relative changes of the Cr and Cu concentration in the algae. The sensitivity of LIBS with a Czerny-Turner spectrometer was fully comparable with the ICP-MS procedure. The trends from LIBS were more similar to the LA-ICP-MS ones. It means that the algae growth inhibition in dependence on the chromium or copper content can be alternatively monitored with LIBS instead of the complicated decomposition procedure in ICP-MS analysis.

Samples with different mechanical and physical properties were measured by LIBS under diverse experimental conditions. The results were used to train a neural network. By means of the neural network, the optimisation process was significantly reduced.

The goal of this work is to examine the effect of a third additional laser pulse on orthogonal double-pulse laser-induced breakdown spectroscopy (DP LIBS). Namely, a pre-ablation laser pulse and re-heating laser pulse were combined into triple-pulse LIBS (3P LIBS) to achieve plasma emission enhancement. The experiment was designed with emphasis on causing minimal sample damage by utilizing nanosecond laser pulses. It means that the energy of ablation laser pulses was set to the minimal value for which the intensities of selected spectral lines were above the limits of detection. This energy as well as the energies of the pre-ablation and the re-heating laser pulses were kept constant for all experimental arrangements. The interpulse delays for both DP LIBS and for 3P LIBS configurations were optimized for signal enhancements. The 3P LIBS results showed up to 5-fold improvement of the signal to background ratio compared with both DP LIBS arrangements and up to 228-fold improvement in comparison to conventional SP LIBS. In addition, it has been shown that the spectral lines with a higher value of excitation energy prove higher enhancement in both DP LIBS and 3P LIBS configurations. To explain this effect, the dimensions of ablation craters were measured for each configuration using a 3D optical microscope and the temperature was determined from the slope of the Boltzmann plot. It was shown that the pre-ablation causes an increase of ablation crater dimensions and the re-heating increases the plasma temperature.

wA simplified method of sulfur determination in asphalt with Laser-Induced Breakdown Spectroscopy on S I 921.29 nm line is presented. Helium at atmospheric pressure was employed in the interaction chamber. Calibration standards were prepared by hand mixing and homogenizing a cellulose or limestone powder with a precise amount of sodium sulfate. Calibration pellets were pressed out and used for quantitative bulk analysis of four asphalt samples. Sulfur content from Inductively Coupled Plasma triple Quadrupole Mass Spectrometry analysis was taken as a reference. The yielded results from the limestone calibration set should be empirically corrected to the microplasma emission which is different from that of cellulose. However, the use of cellulose pellets led directly to true results within experimental uncertainty. Despite evident differences between cellulose and asphalt, there are some hidden factors interconnecting organic matrices and setting mineral ones apart.

The presence of gold nanoparticles on the metallic sample surface positively changes the particle size distribution of the laser ablation aerosol.

We present diagnostics of plasma pencil discharge as alternative excitation source for analytical chemistry. The plasma pencil is special type of rf plasma nozzle at atmospheric pressure. Through this nozzle flows working gas argon with aerosol. The aerosol sample introduction system employed a double pass Scott spray chamber with a pneumatic concentric nebulizer. The parameters of the plasma were calculated by optical emission spectroscopy.

Copper, zinc and sodium atomic line emissions in the pencil plasma under the influence of easily ionizable elements (EIE), counterions and nitric acid were studied.

Nanoparticles (NPs) applied to the surface of some solids can increase signals in inductively coupled plasma mass spectrometry (ICPMS). Drops containing 20 and/or 40 nm nanoparticles of Ag and/or Au were deposited on metallic and ceramic/glass samples, and after being dried, both the samples treated with NPs and plain targets were ablated by one pulse per spot. The laser ablation ICPMS (LA-ICPMS) signals were enhanced for metallic samples modified with NPs in comparison to signals produced at the plain, untreated surface. Maps of LA-ICPMS signals recorded for several laser fluences show that the NP-induced signal enhancement exceeds even 2 orders of magnitude for metallic samples. No enhancement was achieved for nonconductive samples. This enhancement is limited to the peripheral annular region of the dried droplet area where NPs are concentrated due to the "coffee stain" effect. Ablation crater profilometric inspection revealed a more uniform material rearrangement over the NP-treated surface compared with the ablated plain target. However, besides a smoother crater bottom, no other evidence of an NP-enhancing effect was noticed, although an increased ablation rate was anticipated. Limits of detection dropped by 1 order of magnitude for the minor elements in the presence of NPs. Observed phenomena depend only on the NP surface concentration but not on the material or size of the NPs. An electron microprobe study of the collected ablation aerosol has shown that aerosol particles consisting of target material are aggregated around the NPs. The hypothesis is that such aggregates exhibit better transport/vaporization efficiency, thus enhancing signals for metallic samples. A detailed study of the suggested mechanism will be continued in ongoing work.

A LIBS equipment operating at 532nm was optimized and used for sulfur determination in concrete samples. The influence of He atmosphere in a gas-tight chamber (1000–200mbar) on S I 921.29nm line sensitivity, signal-to-background and signal-to-noise ratio was studied at gate delays 100–2000ns. Wide range of gate delays from 500 to about 1000ns and pressures from several hundreds of mbar to the atmospheric pressure can be used for the desired detection of sulfur. The LIBS quantification was done using a simple calibration method. A synthetic limestone enriched by defined amounts of sodium sulfate was newly employed for direct quantification of S in concrete. This powder material was pressed into pellets and ablated with the LIBS system. The average content of sulfur as SO3 in the samples was 0.41–0.70wt% by LIBS and 0.43–0.61wt% by a reference standard procedure employing gravimetry and Inductively Coupled Plasma Triple Quad Mass Spectrometry (ICP-QQQMS). The uncertainty of the yielded LIBS results covers also the dispersion of the points in the calibration line and ranges from 16 to 28% at the probability level of 95%. The uncertainty of the ICP-QQQMS results was almost 10%. No correction on different signal response on the limestone and on the concrete was necessary.

In this work we investigate the relationship of the F line and CaF bands with varying Ca and F contents.

Analysis of concrete is one of the auspiciously developing industrial applications of Laser Induced Breakdown Spectroscopy (LIBS). Knowing the content of chlorine, fluorine and sulfur can be decisive on the current state and security of a particular concrete construction. The sulfur amount in the used cement as a binder of gravel stones in a concrete can influence its solidness. Determination of sulfur in several samples of concrete samples from traffic constructions is the subject of this work. Such task, however, requires more than basic LIBS equipment. Similar to other non-metals, sulfur excitation energies are high and most sensitive emission lines fall to the vacuum ultraviolet range and several much less sensitive lines can be found in visible and lines with higher intensity in near-infrared (NIR) region. To ever visualize the sulfur NIR lines it is often necessary to remove oxygen from the sample neighborhood and to enhance them, helium atmosphere is necessary as well as its pressure should be lowered and further optimized. Owing to the stronger plasma expansion and faster decay of hard lines also the gate delay should be optimized and shifted down to several hundreds of ns. These measurement conditions and parameters and moreover some interference on the emission line S I 921.28 nm were investigated and optimized. The best conditions for maximum lines intensities may not be sometimes applicable due to a parallel increase of an adjacent interfering line. The used LIBS equipment is a SciTrace (AtomTrace) instrument consisting of a 532 nm Q-switched Nd:YAG laser vertically ablating a sample and producing craters of about 0.23 mm in diameter at the pulse energy of 100 mJ. The improvement in detected intensity was investigated in helium atmosphere under various underpressures in a sealed LIBS interaction chamber (AtomTrace). The average content of sulphur was about 0.1-0.3 wt. % by a reference standard procedure employing gravimetry and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). As the LIBS analysis is a spatially resolved method, several spots on the stones without measurable sulfur content were found while the others, in the cement binder, indicate sulfur presence. The obtained sulfur amount from the particular ablation spots is not directly comparable with ICP-MS but a representative average must be taken into account. Simple method using a synthetic limestone enriched by defined amounts of Na2SO4·10H2O was used for achieving the calibration dependence for studied element. This powder material was pressed into pellets and different matrix responses were corrected using selected spectral lines as internal standards.

In this study, the feasibility of Quantum dots (QDs) 2D distribution mapping on the substrate by Laser-Induced Breakdown Spectroscopy (LIBS) was examined. The major objective of this study was to describe phenomena occurring after applying aqueous solutions of QDs onto filtration paper. Especially, the influence of pH and presence of Cu2+ cations in QDs solutions on LIBS signal was investigated. Cadmium Telluride QDs (CdTe QDs) were prepared by formation of nanosized semiconductor particles in so called “one-pot” synthesis. CdTe QDs were capped by glutathione or by 3-mercaptopropionic acid. The technique described in this work allows detection of QDs injected on the selected substrate – filtration paper. Results obtained from LIBS experiments were collated with a comparative method, fluorescence microscopy, which showed variations in the distribution of QDs on the substrate surface and possibilities for quenching. Due to the immediate signal response, relatively simple instrumentation and automatization possibility, LIBS offers promising and fast alternative to other techniques, as it is able to detect also nanoparticles with no visible luminescence.

Laser-induced breakdown spectroscopy (LIBS) is a method with great potential in numerous applications and with the capability to detect broad spectrum of elements. Despite the improvement in instrumentation, it still lacks the appropriate sensitivity for some elements, such as detection of halogens. One of the possibilities how to improve the limits of detection is using reduced ambient pressure atmosphere. Consequently, allowing the species to be easily excited and then to emit characteristic radiation. However, using low-pressure ambient atmosphere leads to fast expansion of plasma contributing to lower plasma temperature and electron density. In this work we propose the utilization of magnetic field in order to confine the plasma plume and thus to increase the plasma temperature, electron density resulting to the detected signal. One of the studied parameters was a plasma size for different combinations of ambient pressures and magnetic fields. Concurrently the influence of pressure and magnetic field on signal and background of selected spectral lines was investigated. Optimization of laser intensity and gate delay was performed for each combination of ambient pressure and magnetic field. Moreover for the optimal conditions was monitored plasma temperature using Saha-Boltzmann plots.

Nowadays, nanotechnologies and preparation of different types of nanoparticles is an emerging field. Quantum dots with their wide range of use (such as labeling and imaging of cancer cells) can be included among the most promising nanoparticles. For all applications the accurate detection of QDs is necessary in the way of qualitative and quantitative spatially resolved analysis. A number of publications regarding instrumental methods used for detection of nanoparticles distribution even in biological samples were already published, but all these methods are highly sophisticated, very expensive and time consuming. Therefore, regarding to its advantages compared to other analytical techniques, the Laser-Induced Breakdown Spectroscopy (LIBS) technique seems to be an adequate and fast alternative. LIBS is a promising alternative to fluorescence methods as it enables detection of both nonluminescent QDs and QDs whose luminescence is affected by external conditions, such as pH change or presence of other metal ions. In our study, the feasibility of QDs 2D distribution mapping on the substrate by LIBS was examined in connection with the separation possibilities; specially interaction QDs with metal cation Cu2+ and also the influence of different pH value of water soluble QDs were investigated. Results obtained from two different LIBS setups were compared and as reference method which showed the exact distribution of QDs on the substrate surface was used the fluorescence microscopy.

The influence of Easily Ionizable Elements (EIE) (chlorides of Na, K, Mg, Ca, Sr and Ba) on the measured spectral lines intensities of copper and zinc excited in a capacitively coupled tubular discharge, known as a plasma pencil, is described.

Multivariate data analysis (MVDA) is getting popular across the spectroscopic community. To assess accurate results, the obtained data should be preprocessed prior to utilization of any MVDA algorithm. The process of data normalization or "internal standardization" is widely used across a broad range of applications. In this manuscript we investigate the utilization of Laser-Induced Breakdown Spectroscopy (LIBS) coupled with MVDA. However, many articles regarding the use of MVDA on data from LIBS do not provide any information about the data pretreatment. This work describes the impact of LIBS data normalization approaches on MVDA classification accuracy. Also, the impact of classical data preprocessing (mean centering and scaling) exploiting the prior utilization of MVDA was studied. This issue was investigated exploiting simple soft independent modelling of class analogies algorithm. The findings were generalized for three sample matrices (steel, Al alloys, and sedimentary ores). Furthermore, the selection of an appropriate normalization algorithm is not trivial since the spectrum of each sample matrix is composed of a different number of elements and corresponding elemental lines.