A Method to Determination of Lead Ions in Aqueous Samples: Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Method Based on Solidification of Floating Organic Drop and Back-Extraction Followed by FAAS

Abstract

Ultrasound-assisted dispersive liquid-liquid microextraction method based on solidification of floating organic drop and back-extraction (UA-DLLME-SFO-BE) technique was proposed for preconcentration of lead ions. In this technique, two SFODME steps are applied in sequence. The classical SFODME was applied as the first step and then the second (back-extraction) step was applied. For the classical SFODME, Pb ions were complexed with Congo red at pH 10.0 and then extracted into 1-dodecanol. After this stage, a second extraction step was performed instead of direct determination of the analyte ion in the classical method. For this purpose, the organic phase containing the extracted analyte ions is treated with 1.0 mol·L−1 HNO3 solution and then exposed to ultrasonication. So, the analyte ions were back-extracted into the aqueous phase. Finally, the analyte ions in the aqueous phase were determined by FAAS directly. Owing to the second extraction step, a clogging problem caused by 1-dodecanol during FAAS determination was avoided. Some parameters which affect the extraction efficiency such as pH, volume of extraction solvent, concentration of complexing agent, type, volume, and concentration of back-extraction solvent, effect of cationic surfactant addition, effect of temperature, and so on were examined. Performed experiments showed that optimum pH was 10.0, 1-dodecanol extraction solvent volume was 75 μL, back-extraction solvent was 500 μL, 1.0 mol·L−1 HNO3, extraction time was 4 min, and extraction temperature was 40°C. Under optimum conditions, the enhancement factor, limit of detection, limit of quantification, and relative standard deviation were calculated as 81, 1.9 μg·L−1, 6.4 μg·L−1, and 3.4% (for 25 μg·L−1 Pb2+), respectively.

Supramolecular solvent based microextraction for the preconcentration of Pb2+ and Cd2+ prior to spectrophotometric detection

“…2, the extraction efficiency of Pb(DHz)2 in 1-dodecanol became maximized at pH 8 and almost constant in the pH range of 10-12. Decrease in recoveries was observed at lower pH value was probably because of competition between Pb 2+ ion and H + ion in reaction for the formation of complex with ligand [24]. The most probable reason behind less recovery of Cd 2+ in acidic medium is, in acidic medium protonation is favored while, in basic medium deprotonation of ligand promotes the metal ligand complexation.…”

CO2-Effervescence in Liquid Phase Microextraction for the Determination of Micropollutants in Environmental Water: a Review

“…These medium chain alcohols are considered to have a melting point below room temperature, so the experimental setup must take the temperature parameters as part of the consideration. If the extraction temperature is less than 25°C, the extraction solvent like 1-dodecanol (melting point of 22-24°C) becomes viscous in the extraction medium and the emulsification process does not take place properly [33].…”

Magnetic Solid-Phase Extraction using Ionic Liquid-Modified Magnetic Nanoparticles for The Simultaneous Extraction of Cadmium and Lead in Milk Samples; Evaluation of Measurement Uncertainty

“…Regarding the importance of measuring the lead and cadmium content, there is a need for a sensitive, repeatable, and accurate analytical method to determine trace amounts of lead and cadmium ions in different types of samples. There are various methods to identify this cation in different samples consisting of graphite furnace atomic absorption (GFAA) [9], inductively coupled plasma emission spectrometry (ICP-OES) [10,11], inductively coupled plasma mass spectrometry (ICP-MS) [12], and Flame atomic absorption spectroscopy (FAAS) [13]. Among these methods, FAAS has been widely used due to its lower costs and ease of application [14].…”