Fully-Automated Fluorimetric Determination of Aluminum in Seawater by In-Syringe Dispersive Liquid–Liquid Microextraction Using Lumogallion

Abstract

A sensitive and selective automated in-syringe dispersive liquid-liquid microextraction (DLLME) method is presented. It was successfully applied to the determination of aluminum in coastal seawater samples. The complete analytical procedure including sampling, buffering, reaction of the analyte with fluorescence reagent lumogallion (LMG), extraction, phase separation, and quantification was completely automized and carried out within 4 min. DLLME was done using n-hexanol as an extracting solvent and ethanol as a dispersing solvent in a 1:8 v/v percent mixture. The Al-LMG complex was extracted by an organic solvent and separated from the aqueous phase within the syringe of an automated syringe pump. Two devices were specially developed for this work. These were (a) the fluorescence detector and accompanying flow cell for the organic phase enriched with the reaction product and (b) a heating device integrated into the holding coil to accelerate the slow reaction kinetics. The limits of detection (3σ) and quantification (10σ) were 8.0 ± 0.5 nmol L(-1) and 26.7 ± 1.6 nmol L(-1), respectively. The relative standard deviation for eight replicate determinations of 200 nmol L(-1) Al(3+) was <1.5%. The calibration graph using the preconcentration system was linear up to 1000 nmol L(-1) with a correlation coefficient of 0.999. Ambient concentrations of samples were quantifiable with found concentrations ranging from 43 to 142 nmol L(-1). Standard additions gave analyte recoveries from 97% to 113% proving the general applicability and adequateness of the analyzer system to real sample analysis.

An automatic, vigorous-injection assisted dispersive liquid–liquid microextraction technique for stopped-flow spectrophotometric detection of boron

“…The modifications enable (1) the automatic vigorous-injection of solvent into the aqueous phase to ensure efficient mixing of the phases; (2) contact between the organic and aqueous phases within a single tubing system to be eliminated; (3) easy direct-forwarding of the extraction phase for the detection step without the use of a holding coil; (4) simple cleaning of the whole system. In comparison with previously reported works, no additional instruments or homemade devices are required, and no special conditions or additional steps, such as magnetic stirring [28,29], heating/cooling [30,31], mixing by air bubbling [22,24] or microcolumn retention/elution [32][33][34][35][36][37] are needed. The suggested approach also satisfies the requirements of environmentally and user-friendly chemistry, since it employs low amounts of organic solvents and all parts of the manifold are commercially available.…”

“…2. No additional instruments or homemade devices are required and no special conditions or additional steps, such as magnetic stirring [28,29], heating/cooling [30,31] or microcolumn retention/elution [32][33][34][35][36][37] are needed. 3.…”

The Automation Technique Lab-In-Syringe: A Practical Guide

“…In the following, steps of analyte derivatization and complexation were added to determine copper and aluminum in water samples as hexanol-soluble complexes with bathocuproine and lumogallion, respectively [14,15]. As in flow-batch, a mixing chamber was added to the flow manifold to enable homogeneous mixing of the sample with the required reagents before carrying out in-syringe DLLME that consequently required intermediate cleaning.…”

Dispersive liquid–liquid microextraction of phenolic compounds from vegetable oils using a magnetic ionic liquid

“…Ionic liquids (ILs) have unique physical and chemical properties, including high chemical and thermal stability, low vapor pressure, and low toxicity , and have therefore become common extraction solvents for sample treatment, especially in dispersive liquid–liquid microextraction . Magnetic ILs favorably combine the excellent properties of ILs with their magnetic properties , and have more advantages and wider application scope in separation processes compared to conventional solvents . The development and use of magnetic ILs is a new field and research hotspot in sample treatment techniques .…”