Speciation of Chromium via Laser-Induced Breakdown Spectroscopy of Ion Exchange Polymer Membranes

2005 ◽  
Vol 59 (2) ◽  
pp. 252-257 ◽  
Author(s):  
Christopher R. Dockery ◽  
Jack E. Pender ◽  
Scott R. Goode
Keyword(s):  
Cation Exchange ◽  
Natural Waters ◽  
Limit Of Detection ◽  
Polymer Membranes ◽  
Solution Concentration ◽  
Laser Induced Breakdown Spectroscopy ◽  
Breakdown Spectroscopy ◽  
Chromium Vi ◽  
Laser Induced Breakdown ◽  
The Matrix

A new method for the speciation of ng/mL concentrations of Cr(III) and Cr(VI) solutions with analysis by laser-induced breakdown spectroscopy (LIBS) is reported. Speciation is achieved by pre-concentration of the chromium onto commercially available cation exchange polymer membranes. Chromium(III) is removed directly by cation exchange; chromium(VI) in the filtrate is reduced to Cr(III) and concentrated onto a second cation exchange membrane, affording independent measurement of both species. Large volumes of waters containing Cr(III) and Cr(VI) can be concentrated onto the membranes and directly analyzed by laser-induced breakdown spectroscopy. The estimated limit of detection corresponds to 500 ng of Cr on the membrane: if a solution volume of 1 L is used, then the detection limit corresponds to a solution concentration of 0.5 ng/mL. Excellent separation of the chromium species is attained. Results show that overall method efficiencies range from 94–116% and are independent of the matrix. The influence of pH has been measured, and although Cr(VI) converts to Cr(III) in acidic solutions, the total Cr recoveries are not appreciably influenced by pH over the range of natural waters (4 to 9). In addition, speciation was performed in the presence of a number of different cations and showed that the method is robust in many different and complex matrices.

Spectral clustering based on histogram of oriented gradient (HOG) of coal using laser-induced breakdown spectroscopy

2021 ◽  
Author(s):  
Ji Chen ◽  
Kaiping Zhan ◽  
Qingzhou Li ◽  
Zhiyang Tang ◽  
Chenwei Zhu ◽  
...  
Keyword(s):  
Spectral Clustering ◽  
Matrix Effects ◽  
Unsupervised Clustering ◽  
Laser Induced Breakdown Spectroscopy ◽  
Histogram Of Oriented Gradient ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
The Matrix ◽  
Quantification Accuracy

The quantification accuracy of laser-induced breakdown spectroscopy was limited due to matrix effects. In this work, a method named unsupervised-clustering-based quantification (UCQ) was proposed to reduce the matrix effects by...

scholarly journals Rapid Determination of Cadmium Contamination in Lettuce Using Laser-Induced Breakdown Spectroscopy

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 2930 ◽  
Author(s):  
Tingting Shen ◽  
Wenwen Kong ◽  
Fei Liu ◽  
Zhenghui Chen ◽  
Jingdong Yao ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Rapid Determination ◽  
Univariate Analysis ◽  
Laser Induced Breakdown Spectroscopy ◽  
Growth Environment ◽  
Breakdown Spectroscopy ◽  
Contamination Degree ◽  
Cd Contamination ◽  
Laser Induced Breakdown

Quick access to cadmium (Cd) contamination in lettuce is important to supervise the leafy vegetable growth environment and market. This study aims to apply laser-induced breakdown spectroscopy (LIBS) technology for fast determination of Cd content and diagnosis of the Cd contamination degree in lettuce. Emission lines Cd II 214.44 nm, Cd II 226.50 nm, and Cd I 228.80 nm were selected to establish the univariate analysis model. Multivariate analysis including partial least squares (PLS) regression, was used to establish Cd content calibration models, and PLS model based on 22 variables selected by genetic algorithm (GA) obtained the best performance with correlation coefficient in the prediction set Rp2 = 0.9716, limit of detection (LOD) = 1.7 mg/kg. K-Nearest Neighbors (KNN) and random forest (RF) were used to analyze Cd contamination degree, and RF model obtained the correct classification rate of 100% in prediction set. The preliminary results indicate LIBS coupled with chemometrics could be used as a fast, efficient and low-cost method to assess Cd contamination in the vegetable industry.

Comparison of the matrix effect in laser induced breakdown spectroscopy analysis of coal particle flow and coal pellets

2021 ◽  
Author(s):  
Ziyu Yu ◽  
Shunchun Yao ◽  
Yuan Jiang ◽  
Weize Chen ◽  
Shuixiu Xu ◽  
...  
Keyword(s):  
Matrix Effect ◽  
Coal Particle ◽  
Particle Flow ◽  
Laser Induced Breakdown Spectroscopy ◽  
Spectroscopy Analysis ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
The Matrix

Laser-induced breakdown spectroscopy analysis of coal particle flow presents milder matrix effect compared with coal pellet.

scholarly journals Quantitative Analysis of Cerium-Gallium Alloys Using a Hand-Held Laser Induced Breakdown Spectroscopy Device

Atoms ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 84 ◽  
Author(s):  
Ashwin P. Rao ◽  
Matthew T. Cook ◽  
Howard L. Hall ◽  
Michael B. Shattan
Keyword(s):  
Emission Line ◽  
Limit Of Detection ◽  
Weight Percent ◽  
Emission Lines ◽  
Resolving Power ◽  
Laser Induced Breakdown Spectroscopy ◽  
Significant Heterogeneity ◽  
Emission Data ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown

A hand-held laser-induced breakdown spectroscopy device was used to acquire spectral emission data from laser-induced plasmas created on the surface of cerium-gallium alloy samples with Ga concentrations ranging from 0–3 weight percent. Ionic and neutral emission lines of the two constituent elements were then extracted and used to generate calibration curves relating the emission line intensity ratios to the gallium concentration of the alloy. The Ga I 287.4-nm emission line was determined to be superior for the purposes of Ga detection and concentration determination. A limit of detection below 0.25% was achieved using a multivariate regression model of the Ga I 287.4-nm line ratio versus two separate Ce II emission lines. This LOD is considered a conservative estimation of the technique’s capability given the type of the calibration samples available and the low power (5 mJ per 1-ns pulse) and resolving power ( λ / Δ λ = 4000) of this hand-held device. Nonetheless, the utility of the technique is demonstrated via a detailed mapping analysis of the surface Ga distribution of a Ce-Ga sample, which reveals significant heterogeneity resulting from the sample production process.

scholarly journals Laser-Induced Breakdown Spectroscopy and Principal Component Analysis for the Classification of Spectra from Gold-Bearing Ores

2019 ◽  
Vol 74 (1) ◽  
pp. 42-54 ◽  
Author(s):  
Daniel Diaz ◽  
Alejandro Molina ◽  
David W. Hahn
Keyword(s):  
Principal Component Analysis ◽  
Limit Of Detection ◽  
Principal Component ◽  
Component Analysis ◽  
Emission Lines ◽  
Laser Induced Breakdown Spectroscopy ◽  
Single Shot ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown

Laser-induced breakdown spectroscopy (LIBS) and principal component analysis (PCA) were applied to the classification of LIBS spectra from gold ores prepared as pressed pellets from pulverized bulk samples. For each sample, 5000 single-shot LIBS spectra were obtained. Although the gold concentrations in the samples were as high as 7.7 µg/g, Au emission lines were not observed in most single-shot LIBS spectra, rendering the application of the usual ensemble-averaging approach for spectral processing to be infeasible. Instead, a PCA approach was utilized to analyze the collection of single-shot LIBS spectra. Two spectral ranges of 21 nm and 0.15 nm wide were considered, and LIBS variables (i.e., wavelengths) reduced to no more than three principal components. Single-shot spectra containing Au emission lines (positive spectra) were discriminated by PCA from those without the spectral feature (negative spectra) in a spectral range of less than 1 nm wide around the Au(I) 267.59 nm emission line. Assuming a discrete gold distribution at very low concentration, LIBS sampling of gold particles seemed unlikely; therefore, positive spectra were considered as data outliers. Detection of data outliers was possible using two PCA statistical parameters, i.e., sample residual and Mahalanobis distance. Results from such a classification were compared with a standard database created with positive spectra identified with a filtering algorithm that rejected spectra with an Au intensity below the smallest detectable analytical LIBS signal (i.e., below the LIBS limit of detection). The PCA approach successfully identified 100% of the data outliers when compared with the standard database. False identifications in the multivariate approach were attributed to variations in shot-to-shot intensity and the presence of interfering emission lines.

Laser-Induced Breakdown Spectroscopy for Detection of Lead in Concrete

1996 ◽  
Vol 50 (7) ◽  
pp. 880-884 ◽  
Author(s):  
Andrew V. Pakhomov ◽  
William Nichols ◽  
Jacek Borysow
Keyword(s):  
Sample Surface ◽  
Lead Contamination ◽  
Laser Induced Breakdown Spectroscopy ◽  
Time Range ◽  
Calibration Function ◽  
Time Resolved ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
The Matrix ◽  
Scale Down

Time-resolved laser-induced breakdown spectroscopy was applied for quantitative measurement of lead content in concrete at levels down to 10 ppm. The breakdown was formed at the sample surface by a Q-switched ND:YAG laser operating at a 1.06-μm wavelength and a repetition rate of 10 Hz. Contamination levels were inferred from the ratio of the integrated emission line of lead to a known reference line of the matrix. The lead contamination can be determined on an absolute scale down to 10 ppm at an optimum delay time of 3.0 μs. These results were derived from analysis of the temporal evolution of the calibration function within a 0.1- to 19.0-μs time range. The calibration function exhibits no dependence on the incident laser pulse energy, which was varied from 250 to 400 mJ.

Quantitative analysis of phosphorus in steel using laser-induced breakdown spectroscopy in air atmosphere

2014 ◽  
Vol 29 (8) ◽  
pp. 1432-1437 ◽  
Author(s):  
Chang Mao Li ◽  
Zhi Min Zou ◽  
Xin Yan Yang ◽  
Zhong Qi Hao ◽  
Lian Bo Guo ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Laser Induced Breakdown Spectroscopy ◽  
Breakdown Spectroscopy ◽  
Strong Interference ◽  
Air Atmosphere ◽  
Laser Induced Breakdown ◽  
The Matrix

The quantitative analysis of phosphorus in iron/steel in air atmosphere is considered a challenge for LIBS due to strong interference from the matrix.

Hydrogen Leak Detection Using Laser-Induced Breakdown Spectroscopy

2005 ◽  
Vol 59 (3) ◽  
pp. 348-353 ◽  
Author(s):  
A. J. Ball ◽  
V. Hohreiter ◽  
D. W. Hahn
Keyword(s):  
Stainless Steel ◽  
Laser Pulse ◽  
Limit Of Detection ◽  
Substrate Surface ◽  
Solid Substrate ◽  
Hydrogen Gas ◽  
Laser Induced Breakdown Spectroscopy ◽  
Stainless Steel Surface ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown

Laser-induced breakdown spectroscopy (LIBS) is investigated as a technique for real-time monitoring of hydrogen gas. Two methodologies were examined: The use of a 100 mJ laser pulse to create a laser-induced breakdown directly in a sample gas stream, and the use of a 55 mJ laser pulse to create a laser-induced plasma on a solid substrate surface, with the expanding plasma sampling the gas stream. Various metals were analyzed as candidate substrate surfaces, including aluminum, copper, molybdenum, stainless steel, titanium, and tungsten. Stainless steel was selected, and a detailed analysis of hydrogen detection in binary mixtures of nitrogen and hydrogen at atmospheric pressure was performed. Both the gaseous plasma and the plasma initiated on the stainless steel surface generated comparable hydrogen emission signals, using the 656.28 Hα emission line, and exhibited excellent signal linearity. The limit of detection is about 20 ppm (mass) as determined for both methodologies, with the solid-initiated plasma yielding a slightly better value. Overall, LIBS is concluded to be a viable candidate for hydrogen sensing, offering a combination of high sensitivity with a technique that is well suited to implementation in field environments.

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