This is the 30th annual review of the application of atomic spectrometry to the chemical analysis of environmental samples. This Update refers to papers published approximately between August 2013 and July 2014 and continues the series of Atomic Spectrometry Updates (ASUs) in environmental analysis that should be read in conjunction with other related ASUs in the series, namely: clinical and biological materials, foods and beverages, advances in atomic spectrometry and related techniques, elemental speciation,X-ray fluorescence spectrometry, and the analysis of metals, chemicals and functional materials. In the field of air analysis, highlights within this review period included: the use of 3D printing technology for the rapid prototyping of new air sampler components; single particle ICP-MS studies; use of a new triple-quadrupole ICP-MS for the analysis of radioactive species and the use of FEG-SEM and IBA for the analysis of gun-shot residues. In the field of water analysis, methods continue to be developed: for the extraction and preconcentration of elements; speciation of As, Cr, Hg and Sb forms and determination of elemental constituents in colloidal and NP fractions. Instrumental developments reported include the use of MC-ICP-MS for isotopic tracer studies and a review of XRF techniques and associated preconcentration procedures for trace element analysis. Many articles featuring the analysis of plants and soils appeared but, as usual, most focused on environmental applications rather than the advancement of atomic spectrometry. There have, however, been interesting developments, such as the almost bewildering increase in types of micro-extraction for analyte preconcentration and the resurgence of CS-AAS. Clearly LIBS is maturing rapidly, with soil analysis becoming more routine in nature. Also notable was the way the accident at the Fukishima-Daiichi nuclear power plant triggered development of analytical methods for the assessment of contamination in the surrounding area. Recent research indicates that geological applications still drives many of the instrumental and methodological advances in LA-ICP-MS. Fundamental studies continue to shed light on the processes involved and hence ways of improving the analysis of laser-produced aerosols. The preparation of NP powders for the production of matrix-matched RMs for microanalytical techniques such as LA-ICP-MS and SIMS showed great promise for addressing one of the major issues when analysing geological materials by these techniques. Steady advances in MC-ICP-MS methodology is feeding through to applications in isotope geochemistry, while new SIMS instrumentation is being directed towards probing fine growth structures in biogenic carbonates and inferring past climate conditions from their geochemistry. Feedback on this review is most welcome and the review coordinator can be contacted using the email address provided.

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Atomic spectrometry update – a review of advances in environmental analysis

Laser-induced breakdown spectroscopy (LIBS) has become an established analytical atomic spectrometry technique and is valued for its very compelling set of advantageous analytical and technical characteristics. It is a rapid, versatile, non-contact technique, which is capable of providing qualitative and quantitative analytical information for practically any sample, in a virtually non-destructive way, without any substantial sample preparation. The instrumentation is simple, robust, compact, and even enables remote analysis. This review attempts to give a critical overview of the diverse progress of the field, focusing on the results of the last five years. The advancement of LIBS instrumentation and data evaluation is discussed in detail and selected results of some prominent applications are also described.

A critical review of recent progress in analytical laser-induced breakdown spectroscopy

Coal is one of the world's most abundant primary energy sources. Real-time coal analysis technology is imperative for coal blending, combustion optimization, pollution reduction, and pricing. Laser-induced breakdown spectroscopy (LIBS) has been a promising candidate for coal analysis because of its uniquely fast, in situ, and online capabilities. Coal is a sedimentary rock with a complex and heterogeneous composition, and therefore, laser–coal interaction exhibits multiple phenomena. A systematic study of the experimental conditions required for stable coal–plasma formation and evolution is a headway for enhancing LIBS results. In coal-fired power plants, LIBS offers three installation sets, namely, inline, at-line, and offline, with minimal space requirements and ease of retrofit. Moreover, LIBS is a safer technique with lower installation and maintenance costs and fits the concern of coal-fired power plants for multielemental detection in fast records. Coal analysis mainly includes calorific heat value determination, proximate analysis, ultimate analysis, and other related analyses. LIBS data is handled with continuously developing mathematical and statistical modeling techniques to provide the smart extraction of the required spectral information for coal analysis. In this tutorial review, we summarize the previous research contributions utilizing LIBS for coal analysis, including fundamentals and key factors, operation modes, data processing, and analytical results. Over and above, LIBS contribution in fly ash analysis and certain literature concerning combustion diagnostics might be included to present a simple guideline for researchers interested in LIBS applications for coal utilization.

Coal analysis by laser-induced breakdown spectroscopy: a tutorial review

A review of the methods of signal enhancement in laser-induced breakdown spectroscopy (LIBS) is presented. Conventional LIBS suffers from disadvantages of low sensitivity and high limits of detecti...

A review of laser-induced breakdown spectroscopy signal enhancement

Laser-Induced Breakdown Spectroscopy (LIBS) applied to terrestrial and extraterrestrial analogue geomaterials with emphasis to minerals and rocks

Laser-induced breakdown spectroscopy (LIBS) as an analytical technique has been developing into a versatile tool in various fields because of its distinct abilities, especially the simple, rapid, in situ detection of any material (solid, liquid, or gas). Following a brief description of LIBS instrumentation, the recent development in the field of geology is reviewed, including the qualitative and quantitative analysis of geological materials, as well as the LIBS application in some specific fields to the analysis of ores, extraterrestrial materials, speleothems, marine sediments, and fluid inclusion.

A Review of Laser-Induced Breakdown Spectroscopy for Analysis of Geological Materials

With massive coal consumption in the industry, the increasing requirements for improving combustion efficiency and environmental protection raise widespread interests. Laser-induced breakdown spectroscopy (LIBS) shows the merits of high-speed, minimally destructive, simple preparation, etc. Combining it with the analytical chemistry methods have become a promising way for coal analysis. In this work, LIBS instruments for collecting coal spectra, pretreatment methods for coal samples, preprocessing of coal data, and analytical chemistry methods for coal analysis were summarized. Moreover, LIBS applications, including coal ranks, combustion efficiency, and environmental protection, are provided. Finally, this review proposes a description of limitations and the potential developing trend for this topic.

A review of laser-induced breakdown spectroscopy for plastic analysis

It is crucial to make comprehensive assessments of soil under economic and efficiency requirements in order to guide the rational use of soil resources, including the identification of attributes, the control of pollutants, and the management of nutrients. Laser induced breakdown spectroscopy (LIBS) is excellent for such applications due to its unique advantages of simple preparation, rapid measurement, and multiple-element analysis. An analysis of Si, Al, Mg, Ca, Na, K, Mn, Ba, Ti, Cr, Cu, Sr and P in different standard soils using LIBS is reported here for the comparison of the quantitative results of a univariate regression method (calibration curve) and two multivariate regression methods (partial least squares regression (PLSR) and support vector regression (SVR)). As a result, the correlation coefficients (R2) of the Ca, K, Mg, Na and Sr elements were all greater than 0.90, while the calibration curves of Al, Ba, Cr, Cu, Mn, Ti and P presented poor linear performances with low R2 values of below 0.90. The robustness of the SVR model was superior to the PLSR model with a better prediction ability and a lower relative standard deviation (RSD) for both the training data and the test data, whilst the opposite was observed for the predicted data set used as external verification. The predicted relative errors of the prediction data given by PLSR for all analysis elements except Na and K were lower than those given by SVR. The relative errors of PLSR for Si, Al and Sr were within 10%, while the values for the other elements were between 10% and 20%, and 45% for Cu. It is therefore meaningful to propose a quantitative reference among the univariate linear regression, the multivariate linear regression and the multivariate nonlinear regression methods for the multi-element analysis of soil samples under complex matrix conditions.

Multi-element quantitative analysis of soils by laser induced breakdown spectroscopy (LIBS) coupled with univariate and multivariate regression methods

With the extensive use of plastic products, the recycling and reuse of plastics raise more concerns. Laser-induced breakdown spectroscopy (LIBS) and chemometric methods have been applied to classify plastics. However, the methods are prone to fall into over-fitting when predicting unknown samples. Variable importance is the impact of input variables to classification results. Selecting input variables by variable importance can be used to avoid over-fitting, which has been used for improving model performance based on random forest (RF). However, the progress of optimizing the parameters of RF model is complex. Partial least squares discrimination analysis (PLS-DA), most widely used in spectral data, is a simple and stable method in multivariate analysis. To avoid over-fitting phenomenon and acquire stable results, this paper presents an extension of PLS-DA that uses variable importance to select input variables, namely VI-PLS-DA. In order to validate the classification ability of VI-PLS-DA for plastics, VI-PLS-DA was compared with PLS-DA, RF, and VI-RF. VI-PLS-DA has the highest classification accuracy (99.55%) and shortest classification time (0.096 ms), which indicated a good classification performance for plastics analysis.

Rapid classification of plastics by laser-induced breakdown spectroscopy (LIBS) coupled with partial least squares discrimination analysis based on variable importance (VI-PLS-DA)

Di Tian

Papers

A review of laser-induced breakdown spectroscopy signal enhancement

A Review of Laser-Induced Breakdown Spectroscopy for Analysis of Geological Materials

A review of laser-induced breakdown spectroscopy for plastic analysis

Multi-element quantitative analysis of soils by laser induced breakdown spectroscopy (LIBS) coupled with univariate and multivariate regression methods

Rapid classification of plastics by laser-induced breakdown spectroscopy (LIBS) coupled with partial least squares discrimination analysis based on variable importance (VI-PLS-DA)