Heavy metals; Detection; Voltammetry; Environmental testing; Field characterization; E-Tongue; Arsenic; Cadmium; Lead; Mercury; Zinc;INDUCED BREAKDOWN SPECTROSCOPY; ANODIC-STRIPPING VOLTAMMETRY; SCREEN-PRINTED ELECTRODES; ORGANIC POLYMERS; SOILS; GROUNDWATER; SYSTEM; FLUORESCENCE; ENVIRONMENT; SUBSURFACE

Heavy metals from both natural and anthropogenic sources present a significant risk to human and environmental health. A number of methods have been developed for the detection and quantification of heavy metals. These methods include laboratory analysis, onsite testing of samples, and in situ techniques. This paper will review current and emerging technologies for site characterization with a specific focus on in situ detection of heavy metal contamination in geoenvironmental remediation projects. In addition, on-going research performed for the development of an in situ voltammetric sensor system will be presented. A number of devices exist for the efficient sampling of contaminated groundwater including the Hydropunch, BAT system, and Cone Sipper. Samples may either be sent to a laboratory for analysis with techniques such as atomic absorption spectroscopy, inductively coupled plasma-mass spectrometry, atomic emission spectroscopy, and X-ray fluorescence, or analyzed onsite using methods such as colorimetry, voltammetry, or biological based chemical sensors. For in situ analysis of heavy metals in soil, X-ray fluorescence and laser induced breakdown spectroscopy technologies have been integrated with the cone penetrometer probe. This paper further explores the feasibility of integrating electrochemical techniques based on voltammetry for the in situ detection of aqueous metal ions. The development of bismuth, gold nanoparticle, and polymer modified electrodes allow for the detection of heavy metal contaminants, including lead, cadmium, mercury and arsenic, at low part per billion levels.

LIBS; Trace-element premixes; Univariate analysis; Multivariate analysis; PLS;SPECTROCHEMICAL ANALYSIS; LIBS; ADULTERATION; COPPER; MILK; BEEF

Infant formula is a human milk substitute generally based upon fortified cow milk components. In order to mimic the composition of breast milk, trace elements such as copper, iron and zinc are usually added in a single operation using a premix. The correct-addition of premixes must be verified to ensure that the target levels in infant formulae are achieved. In this study, a laser-induced breakdown spectroscopy (LIBS) system was assessed as a fast validation tool for trace element premixes. LIBS is a promising emission spectroscopic technique for elemental analysis, which offers real-time analyses, little to no sample preparation and ease of use. LIBS was employed for copper and iron determinations of premix samples ranging approximately from 0 to 120 mg/kg Cu/1640 mg/kg Fe. LIES spectra are affected by several parameters, hindering subsequent quantitative analyses. This work aimed at testing three matrix-matched calibration approaches (simple-linear regression, multi-linear regression and partial least squares regression (PLS)) as means for precision and accuracy enhancement of LIBS quantitative analysis. All calibration models were first developed using a training set and then validated with an independent test set. PLS yielded the best results. For instance, the PLS model for copper provided a coefficient of determination (R-2) of 0.995 and a root mean square error of prediction (RMSEP) of 14 mg/kg. Furthermore, LIBS was employed to penetrate through the samples by repetitively measuring the same spot. Consequently, LIBS spectra can be obtained as a function of sample layers. This information was used to explore whether measuring deeper into the sample could reduce possible surface-contaminant effects and provide better quantifications. (C) 2017 Elsevier B.V. All rights reserved.

LIBS; Minced beef; Rubidium; PLSR; Chemometrics;MEAT; CLASSIFICATION; LIBS

This study evaluates the potential of laser induced breakdown spectroscopy (LIBS) coupled with chemometrics to develop a quantification model for rubidium (Rb) in minced beef. A LIBSCAN 150 system was used to collect LIBS spectra of minced beef samples. Beef liver was used to spike the Rb levels in minced beef. All samples were dried, powdered and pelleted using a hydraulic press. Measurements were conducted by scanning 100 different locations with an automated XYZ sample chamber. Partial least squares regression (PLSR) was used to develop the calibration model, yielding a calibration coefficient of determination (R-c(2)) of 0.99 and a root mean square error of calibration (RMSEC) of 0.05 ppm. The model also showed good results with leave-one-out cross validation, yielding a cross-validation coefficient of determination (R-c(2)) of 0.90 and a root mean square error of cross-validation (RMSECV) of 0.22 ppm. The current study shows the potential of LIBS as a rapid analysis tool for the meat processing industry.

LIBS; Mineral composition; Analytical technique; Food; Chemometrics;PLANT MATERIALS; WHEAT-FLOUR; CLASSIFICATION; ADULTERATION; SPECTROMETRY; IDENTIFICATION; CHEMOMETRICS; VALIDATION; EMISSION; STANDARD

Background: Laser-induced breakdown spectroscopy (LIBS) is an atomic emission spectroscopic technique which uses a focused pulsed laser beam to generate plasma from the material. The plasma contains atoms, ions and free electrons which emit electromagnetic radiation as the plasma cools down. The emitted light is resolved by a spectrometer to form a spectrum. Recently, LIBS has become an emerging analytical technique for characterisation and identification of materials; its multi-elemental analysis, fast response, remote sensing, little to no sample preparation, low running cost and ease of use make LIBS a promising technique for the food sector. Scope and approach: The present article reviews the feasibility of LIBS for food analysis. It presents recent progress and applications of LIBS as an efficient and reagent-free, at-line tool capable of replacing traditional time-consuming analytical methods for assessing the quality and composition of food products. An overview of LIBS fundamentals, instrumentation and statistical data analysis is also provided. Key findings and conclusions: Although LIBS technology shows many advantages, challenges remain in terms of sample preparation, matrix effects, spectral pre-processing, model calibration and instrument development. (C) 2017 Elsevier Ltd. All rights reserved.

LIBS; Beef; Offal; Copper; PLSR; Chemometrics;MOTION CONDITIONS; TRACE-ELEMENTS; MEAT; SPECTROMETRY; LIBS; CLASSIFICATION; PREDICTION; SAMPLES

Laser induced breakdown spectroscopy (LIBS) is an emerging technique in the field of food analysis which provides various advantages such as minimal sample preparation, chemical free, rapid detection, provision of spatial information and portability. In this study, LIBS was employed for quantitative analysis of copper content in minced beef samples spiked with beef liver over three independent batches. Copper content was determined with graphite furnace atomic absorption spectroscopy (GFAAS) in order to obtain reference values for modelling. Partial least square regression (PLSR) was performed to build a calibration and validation model. A calibration model with a high R-cv(2) of 0.85 and a RMSECV of 43.5 ppm was obtained, confirming a good fit for the model. The validation model showed a good prediction accuracy with a high R-p(2) of 0.85 and RMSEP of 36.8 ppm. Moreover, on a further study to evaluate the spatial capabilities, LIBS was able to successfully map copper content within a pellet, indicating the suitability of LIBS to provide spatial information and therefore potential use on heterogeneous samples. Overall, it can be concluded that LIBS combined with chemometrics demonstrates potential as a quality monitoring tool for the meat processing industry.

NIR SPECTROSCOPY; DATA NORMALIZATION; MOTION CONDITIONS; INFANT FORMULA; DIETARY-SODIUM; BLOOD-PRESSURE; MEAT; LIBS; CLASSIFICATION; PREDICTION

Beef is a rich source of important minerals, with potassium (K) being the most abundant mineral quantitatively except in cured meats where sodium (Na) from the added salt predominates. This study evaluates the capability of LIBS for quantification of the Na and K contents of minced beef as a potential method of detecting beef kidney adulteration. Additionally, the study aims to demonstrate the ability of LIBS to provide spatial mineral information of minced beef. A LIBS system was employed to collect spectral information of adulterated minced beef samples. Atomic absorption spectroscopy (AAS) was used to obtain reference values for Na and K. The chemometric technique of partial least squares regression (PLSR) was used to build the prediction models. Spatial mineral maps of minced beef samples were generated based on the predicted percentages of Na and K. The models for Na and K yielded calibration coefficients of determination (R-c(2)) of 0.97 and 0.91 respectively. Similarly, a good calibration model was obtained for adulteration yielding a R-c(2) of 0.97. Good prediction accuracy was observed for all models. Spatial mapping provided two major advantages: (a) representative measurements of samples and (b) spatial distribution of multi-elements. The results observed illustrate the ability of LIBS combined with chemometrics as a potential monitoring tool for mineral quantification as well as adulteration detection for the meat processing industry.