Laser Induced Breakdown Spectroscopy; Milk adulteration; Melamine; Neural networks;NEURAL-NETWORKS; POWDER ADULTERATION; VEGETABLE-OILS; BETA-CAROTENE; DISCRIMINATION; CLASSIFICATION; LYCOPENE; FATS; MS

The present work focuses on the development of a fast and cost effective method based on Laser Induced Breakdown Spectroscopy (LIBS) to the quality control, traceability and detection of adulteration in milk. Two adulteration cases have been studied; a qualitative analysis for the discrimination between different milk blends and quantification of melamine in adulterated toddler milk powder. Principal Component Analysis (PCA) and neural networks (NN) have been used to analyze LIBS spectra obtaining a correct classification rate of 98% with a 100% of robustness. For the quantification of melamine, two methodologies have been developed; univariate analysis using CN emission band and multivariate calibration NN model obtaining correlation coefficient (R-2) values of 0.982 and 0.999 respectively. The results of the use of LIBS technique coupled with chemometric analysis are discussed in terms of its potential use in the food industry to perform the quality control of this dairy product. (C) 2017 Elsevier Ltd. All rights reserved.

LIBS imaging; Elemental imaging; Human paraffin-embedded tissue; Skin cancer;PLASMA-MASS SPECTROMETRY; SQUAMOUS-CELL CARCINOMA; X-RAY MICROSCOPY; LA-ICP-MS; BIOLOGICAL TISSUE; NANOPARTICLES; SKIN; RESOLUTION; ELEMENTS; METALS

Chemical elements play central roles for physiological homeostasis in human cells, and their dysregulation might lead to a certain number of pathologies. Novel imaging techniques that improve the work of pathologists for tissue analysis and diagnostics are continuously sought. We report the use of Laser-Induced Breakdown Spectroscopy (LIBS) to perform multi-elemental images of human paraffin-embedded skin samples on the entire biopsy scale in a complementary and compatible way with microscope histopathological examination. A specific instrumental configuration is proposed in order to detect most of the elements of medical interest (i.e. P, Al, Mg, Na, Zn, Si, Fe, and Cu). As an example of medical application, we selected and analysed skin biopsies, including healthy skin tissue, cutaneous metastasis of melanoma, Merkel-cell carcinoma and squamous cell carcinoma. Clear distinctions in the distribution of chemical elements are observed from the different samples investigated. This study demonstrates the high complementarity of LIBS elemental imaging with conventional histopathology, opening new opportunities for any medical application involving metals. (C) 2017 Elsevier B.V. All rights reserved.

INDUCED PLASMA SPECTROSCOPY; ATOMIC EMISSION-SPECTROMETRY; VACUUM-ULTRAVIOLET; SULFUR; STEEL; NANOPARTICLES; CALIBRATION; SAMPLES; RATIOS; SYSTEM

This work introduces a new approach to perform LIBS elemental imaging in the vacuum ultraviolet (VUV) wavelength range by using an argon purged probe coupled to a compact spectrometer. In spite of several important elements for geological and industrial applications such as S, P, As, B, C, or Zn presenting strong lines in the VUV range, the need for using specific optics and working under oxygen-free conditions has limited the extension of LIBS systems available for such a range. Herein, we present an adaptation of our LIBS imaging instrumentation to access the VUV while operating under ambient conditions. The proposed detection system is based on an optical probe directly coupled to a Maya2000Pro compact spectrometer (Ocean Optics), all purged with argon. The technical design along with a detailed evaluation of the VUV probe is addressed. The possibility of using this VUV probe for LIBS imaging is also investigated by studying a Canadian mine core sample with special emphasis on the detection of sulfur. In addition to sulfur, more than 15 elements including P, As, C, Ca, Si, Mo, B, and Zn have also been detected. Elemental images covering sample surfaces in the range of cm(2) with a micrometric spatial resolution (10 mu m) are presented. A detection limit of 0.2 wt% for sulfur is demonstrated in a single shot configuration. These results open new perspectives for both conventional LIBS and LIBS-based imaging in various application fields.

STALAGMITE LAMINAE; TRACE-ELEMENTS; SR-ISOTOPE; SPELEOTHEMS; GROWTH; RATIOS; SPECTROMETRY; SYSTEMATICS; SKELETON; SIGNALS

Paleoclimate studies play a crucial role in understanding past and future climates and their environmental impacts. Current methodologies for performing highly sensitive elemental analysis at micrometre spatial resolutions are restricted to the use of complex and/or not easily applied techniques, such as synchrotron radiation X-ray fluorescence micro- analysis (mu-SRXRF), nano secondary ion mass spectrometry (nano-SIMS) or laser ablation inductively coupled plasma mass spectrometry (LAICP-MS). Moreover, the analysis of large samples (> few cm 2) with any of these methods remains very challenging due to their relatively low acquisition speed(similar to 1-10Hz), and because they must be operated in vacuum or controlled atmosphere. In this work, we proposed an imaging methodology based on laser-induced breakdown spectroscopy, to perform fast multi-elemental scanning of large geological samples with high performance in terms of sensitivity (ppm-level), lateral resolution (up to 10 mu m) and operating speed (100 Hz). This method was successfully applied to obtain the first megapixel images of large geological samples and yielded new information, not accessible using other techniques. These results open a new perspective into the use of laser spectroscopy in a variety of geochemical applications.

LIBS; Quantification; Elemental imaging; Elemental profile; Heterogeneous catalyst; Palladium;X-RAY-FLUORESCENCE; FLIGHT MASS-SPECTROMETRY; HIGH-SPEED; GEOLOGICAL SAMPLES; HIGH-RESOLUTION; TRACE-ELEMENTS; CONVERTERS; METALS; MICROANALYSIS; MICROPROBE

Currently, the use of catalysis is widespread in almost all industrial processes; its use improves productivity, synthesis yields and waste treatment as well as decreases energy costs. The increasingly stringent requirements, in terms of reaction selectivity and environmental standards, impose progressively increasing accuracy and control of operations. Meanwhile, the development of characterization techniques has been challenging, and the techniques often require equipment with high complexity. In this paper, we demonstrate a novel elemental approach for performing quantitative space-resolved analysis with ppm-scale quantification limits and mu m-scale resolution. This approach, based on laser-induced breakdown spectroscopy (LIBS), is distinguished by its simplicity, all-optical design, and speed of operation. This work analyzes palladium-based porous alumina catalysts, which are commonly used in the selective hydrogenation process, using the LIBS method. We report an exhaustive study of the quantification capability of LIBS and its ability to perform imaging measurements over a large dynamic range, typically from a few ppm to wt. These results offer new (i)nsight into the use of LIBS-based imaging in the industry and paves the way for innumerable applications. (C) 2017 Elsevier B.V. All rights reserved.