Melted Paraffin Wax as an Innovative Liquid and Solid Extractant for Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Abstract

This work proposes a new development in the use of melted paraffin wax as a new extractant in a procedure designed to aggregate the advantages of liquid phase extraction (extract homogeneity, fast, and efficient transfer, low cost and simplicity) to solid phase extraction. As proof of concept, copper(II) in aqueous samples was converted into a hydrophobic complex of copper(II) diethyldithiocarbamate and subsequently extracted into paraffin wax. Parameters which affect the complexation and extraction (pH, DDTC, and Triton X-100 concentration, vortex agitation time and complexation time) were optimized in a univariate way. The combination of the extraction proposed procedure with laser-induced breakdown spectroscopy allowed the precise copper determination (coefficient of variation = 3.1%, n = 10) and enhanced detectability because of the concentration factor of 18 times. A calibration curve was obtained with a linear range of 0.50-10.00 mg L (R = 0.9990, n = 7), LOD = 0.12 mg L, and LOQ = 0.38 mg L under optimized conditions. An extraction procedure efficiency of 94% was obtained. The accuracy of the method was confirmed through the analysis of a reference material of human blood serum, by the spike and recovery trials with seawater, tap water, mineral water, and alcoholic beverages and by comparing with those results obtained by graphite furnace atomic absorption spectrometry.

Traditional Calibration Methods in Atomic Spectrometry and New Calibration Strategies for Inductively Coupled Plasma Mass Spectrometry

“…The EC method has been effective in several analytical applications involving elemental determination in different types of the matrices, such as crude oils (Trevelin et al, 2016 ; Sugiyama and Williams-Jones, 2018 ), diesel oil (Nora et al, 2017 ), biodiesel (Barros et al, 2017 ), iron supplements (Barbosa et al, 2015 ), vinegar alcohol (Silva Junior et al, 2015 ), sediment (Leao et al, 2016b ), milk (Oliveira et al, 2017 ), canned foods (Leao et al, 2016a ), seawater, mineral water, tap water, cachaça, human blood (Papai et al, 2017 ), among others. In these applications, acid digestion (Barbosa et al, 2015 ; Leao et al, 2016a ; Sugiyama and Williams-Jones, 2018 ), dry decomposition (Nora et al, 2017 ), extraction procedures (Silva Junior et al, 2015 ; Leao et al, 2016b ; Sánchez et al, 2016 ; Trevelin et al, 2016 ; Barros et al, 2017 ; Papai et al, 2017 ; Zeiner et al, 2018 ), and emulsion formation (Oliveira et al, 2017 ) were used for sample preparation. Table 1 shows a summary and additional details on sample preparation procedures used in combination with EC, as well as with MMC.…”

Laser Induced-Breakdown Spectroscopy (Libs): Histórico, Fundamentos, Aplicações E Potencialidades

“…Posteriormente, essa argila foi prensada para obtenção de pastilhas que foram analisadas diretamente pela LIBS. Já Papai et al 62 propuseram um método para extração de íons de cobre em solução aquosa em parafina. Para tanto, após a adição de alguns reagentes a 10 mL de solução aquosa contendo cobre, 700 µL de parafina derretida foi adicionada à solução e, após homogeneização em vortex, 600 µL dessa parafina foi extraída e posicionada em um suporte de acrílico para secagem e posterior análise direta em LIBS.…”

Investigating silicon wafer based substrates for dried-droplet analysis by Laser-Induced Breakdown Spectroscopy

“…However, due to some experimental challenges in direct liquid analysis by LIBS, significant amount of work in the literature is based on the method development studies for converting the sample matrix from liquid to solid phase. Approaches like; freezing into ice [3], use of several adsorbent materials like filter paper [4,5], graphite [6], wood slices [7] and calcium hydroxide pellets [8], utilization of ionexchange [9,10] and PVC membranes [11], solidification techniques based on formation of hydro gels [12] and cross-linked PVA polymer film [13], enrichment by electro deposition [14,15] and various preconcentration techniques [16][17][18][19] and deposition of silver and gold nanoparticles on the sample surface (NELIBS) [20] provide element and substrate-specific enhancements in signal intensities and hence, improvements up to orders of magnitude in detection limits are reported.…”