Coupling dispersive liquid-liquid microextraction to inductively coupled plasma atomic emission spectrometry: An oxymoron?

Abstract

Coupling dispersive liquid-liquid micro-extraction (DLLME) to inductively coupled plasma atomic emission spectrometry (ICP-AES) is usually troublesome due to the limited plasma tolerance to the organic solvents usually employed for metal extraction. This work explores different coupling strategies allowing the multi-element determination by ICP-AES of the solutions obtained after DLLME procedures. To this end, three of the most common extractant solvents in DLLME procedures (1-undecanol, 1-butyl-3-methyl-imidazolium hexafluorophosphate and chloroform) have been selected to face most of the main problems reported in DLLME-ICP-AES coupling (i.e., those arising from the high solvent viscosity and volatility). Results demonstrate that DLLME can be successfully coupled to ICP-AES after a careful optimization of the experimental conditions. Thus, elemental analysis in 1-undecanol and 1-butyl-3-methyl-imidazolium hexafluorophosphate extracts can be achieved by ICP-AES after a simple dilution step with methanol (1:0.5). Chloroform can be directly introduced into the plasma with minimum changes in the ICP-AES configuration usually employed when operating with aqueous solutions. Diluted inorganic acid solutions (1% w w either nitric or hydrochloric acids) have been successfully tested for the first time as a carrier for the introduction of organic extractants in ICP-AES. The coupling strategies proposed have been successfully applied to the multi-element analysis (Al, Cu, Fe, Mn, Ni and Zn) of different water samples (i.e. marine, tap and river) by DLLME-ICP-AES.

Development of preconcentration strategies for the simultaneous ultratrace determination of As, Cd and Pb in foods by ICP-OES: knotted-reactor vs. dispersive liquid–liquid microextraction

“…In fact, operating organic solvents could be potentially beneficial to improve the analytical figures of merit in comparison to inorganic acid solutions since organics affords higher aerosol generation and analyte transport. 14 In the present work, the possibility of applying organic solvents with KR in ICP-OES was investigated. To this end, several modifications were introduced in the experimental arrangement usually employed in ICP-OES.…”

“…On the other hand, to improve plasma stability operating with organic solvents, eluates from the KR were introduced into the ICP-OES by means of a flow injection analysis (FIA)-manifold using a 1% w w -1 nitric acid solution as the carrier medium. 14 First, the influence of the elution solvent on analyte signal in ICP-OES was evaluated. To this end, a 1 mg L -1 As(III), Cd(II) and Pb(II) standard solution was preconcentrated within the KR according to the experimental procedure described in the Experimental section.…”

“…13 Nevertheless, these strategies increase the complexity of the analysis, raise costs and reduce sample throughput. Martinez 5 et al 14 have recently demonstrated that some organic extracts used in DLLME (e.g. chloroform, 1-undecanol and 1-butyl-3-methylimidazolium hexafluorophosphate) can be directly analyzed by means of ICP-OES.…”

Atomic Spectrometry Update – a review of advances in environmental analysis

“…Although popular for AAS analysis, the use of DLLME with plasma instruments is not particularly favoured due to the viscosity of the solvents used. Researchers in Spain employed 85 three of the most commonly used solvents in DLLME procedures (1-undecanol, the ionic liquid 1-butyl-3-methyl-imidazolium hexafluorophosphate and chloroform) to investigate the main problems experienced when coupling DLLME with ICP-AES. The first two solvents are very viscous and immiscible with water so simple dilution (1+1 or 1+0.5) with methanol improved their nebulisation and transport efficiency.…”

Platinum Nanoparticle in Tantalum Electrode for the Electrochemical Analysis of Heavy Metal Ions Formed by the Ion Beam Sputtering Deposition

“…Excessive Cu 2+ can also be blamed for other illnesses, including hemochromatosis, catarrh, calf cramps, scalp dermatitis brass chills and Wilson's [4]. Several methods have been employed for detecting heavy metal ions, for instance, the use of atomic electron emission spectrometry (ICP / AES, ICP / MS), flow-injection spectroscopy (FIAAS), and high resolution liquid chromatography (HPLC) [5][6][7]. However, where the concentration spectrum of these metal ions is wide, it is difficult to examine specifically heightened metal ions using these techniques.…”