Laser-induced breakdown spectroscopy determination of K in biochar-based fertilizers in the presence of easily ionizable element

Abstract

Laser-induced breakdown spectroscopy is an optical emission technique quite suitable for the analysis of recalcitrant materials as it eliminates complex procedures of sample preparation. However, for some simple LIBS instrumentation the detection limits are still higher compared to those of consolidated spectroscopic techniques. The aim of the present work was to develop a method for the determination of K in new biochar-based fertilizer samples using a simple single pulse LIBS arrangement. Due to the low K detectability, which made impossible to obtain calibration curves, an exploratory qualitative study was performed aiming to evaluate the influence of the addition of easily ionizable elements (EIE) on the sensitivity. To this aim different salts containing EIE (K, Li and Na) and other cations (Cu and Mg) have been evaluated. Results obtained showed that salts containing EIE cations increased the spectral emission signals of some elements in samples previously submitted to charring. In particular, the strategy of using Li was applied to the determination of K in biochar-based fertilizers. The addition of Li allowed to develop an analytical method for K determination featuring a linear dynamic range from 0.8% to 21.56% K, and limits of detection and quantification of 0.2% and 0.8%, respectively.

Determination of scaling ions in oilfield produced water by laser-induced breakdown spectroscopy

“…40 Therefore, a higher electronic density and plasma temperature are expected, which is reflected as an increase in emission intensity. Morais et al 41 used another easily ionizable element, Li (5.39 eV), incorporated in solid matrices for K determination, which provided an increase in emission signals. Easily ionizable elements can be used to enhance the LIBS signal to improve the sensitivity for refractory elements or those present in low concentrations.…”

Underwater determination of calcium and strontium ions in oilfield produced water by laser-induced breakdown spectroscopy (LIBS)

“…This phenomenon favours a high electron density and increases populations of excited levels, reecting the increase in the observed emission intensity. 24,36,37 On the other hand, when the salinity varies from 5& to 50&, there is a small decrease in the emission signals.…”

Optimization of laser-induced breakdown spectroscopy parameters from the design of experiments for multi-element qualitative analysis in river sediment

“…The sensitivity of the single pulse (SP) LIBS system can be increased using different kinds of experimental setups, such as double pulse (DP) LIBS [2,3], resonance-enhanced LIBS [4,5], microwave-assisted LIBS [6], spark discharge LIBS [7,8], spatial confinement of laser-induced plasma [9], and the use of a micro-torch [10]. In addition to instrumental techniques to improve the sensitivity of LIBS, strategies involving sample pretreatment have been used, such as the deposition of nanoparticles onto samples [11] and the addition of a salt containing easily ionizable elements [12].…”