Development of a laser-induced breakdown spectroscopy method for soil and ecological analysis (review)

Abstract

The application of laser spectrochemical analysis to testing for basic compounds and nutritious/toxic elements in soil has been reviewed. A combined laser-spark approach has been applied for the rapid measurement of the carbon content in soil. Spectra have been excited both directly in a laser-ablation plume and by passing a pulsed electric discharge through the plume. The emission spectrum intensity in the combined plasma is considerably higher. The application of a complex of methods to carbon determination in soil has shown that in fact the data on the humus content usually obtained in agrochemical practice by a conventional method of carbon oxidation by potassium dichromate need to be corrected taking into account the possibility of incomplete oxidation of organic matter in soil. The efficiency of various double-pulse LIBS applications has been demonstrated in solving a number of environmental problems such as the determination of heavy and toxic metals in soil and the detection of sulfur in coal. The instrumentation and analytical procedures have been proposed and optimized for rapid control of the chlorine content in plant samples. The technique can be easily extended to ecological monitoring of toxic elements and heavy metals in any biogenic material.Introduction. Laser methods for analyzing the composition of soil, ore, minerals, and related materials have been developing rapidly for the last decade. A comprehensive review of these methods reveals that the technology for performing the analytical procedures, the equipment, and the techniques for processing results are similar. The employed methods are based on emission spectroscopy, fluorescence, Raman scattering, IR reflectance from the samples, etc. Laser-induced breakdown spectroscopy (LIBS) is promoted as a primary technique. This method was developed very early [1-4] and is sufficiently validated for solving various practical problems such as quality control of industrial products [5], processes [6], the environmental situation [7], water resources [8], and the composition of ores and minerals [9] in addition to problems in criminology for detecting explosives [10], pharmacology [11], archeology and art [12], and biological samples [13]. This method is used in agricultural chemistry to determine the soil content of carbon, which characterizes the humus content, and several nutritious elements and toxins [14][15][16]. For this, LIBS factors such as simple sample preparation for analysis, rapid processing of results and their distribution, and prospects for determining the soil composition under field conditions are important [17].Because soil has a complicated background composition, it is analyzed as a rule by calibrating instruments using certified samples (standards). These standards can differ in complexity even for solving similar problems depending on the matrix of samples subject to analysis. For example, the determination of C in chernozem and loamy soils and rocky and peaty ores cannot be carried out using single certified samples. Standards ...

Physical and Chemical Matrix Effects in Soil Carbon Quantification Using Laser-Induced Breakdown Spectroscopy

“…However, LIBS has some precision limitations with regard to variation in the physical and chemical properties of the different materials present in soil, known as matrix effects [12] [14] [16]. After these limitations have been solved and the system has been calibrated using samples with known concentrations of an element of interest, LIBS has been used for determining metals, minerals, C and other important elements in soil [11] [12]; therefore, there is great potential for the development of portable LIBS equipment for the field-based quantification of C in soil [8] [17].…”

Signal enhancement in collinear double-pulse laser-induced breakdown spectroscopy applied to different soils

“…The LIBS technique has been applied successfully to soils for assessing their elemental composition, classification, presence of contaminants, etc [27,31,[34][35][36][37][38][39]. LIBS is a quick and environmentally clean technique, and does not require the use of reagents for sample preparation, thus has great potential for application to soils.…”

“…are directed orthogonal to the sample surface, yields an increase of emission line intensities which ranges from a factor of 2 [20] up to a factor of 100 [13,21], although the large variety of enhancements observed is not well understood. DP LIBS in collinear geometry has been applied to analyze various types of materials in the liquid form [22][23][24][25], solid form, including metals and various environmental samples [13,14,[25][26][27][28][29][30][31], and solid targets in liquids [32]. Further, DP experiments in collinear geometry can be performed either using a unique laser [14,20,22,32] or two lasers [13,15,23,28].…”

Elemental Composition Analysis of Plants and Composts Used for Soil Remediation by Laser‐Induced Breakdown Spectroscopy

“…Some LIBS peculiarities are: light-element detection, particularly useful for material identification; and depth profiling and elemental surface mapping, which helps in solving several scientific and practical problems in real-time. For these reasons, LIBS has been recently used for multi-elemental analysis of biological and environmental samples including soils [7][8][9][10], plant materials [11][12][13][14][15], and geological specimens [16][17][18].…”