Continuous-Flow Microextraction Exceeding1000-Fold Concentration of Dilute Analytes

Abstract

A novel liquid-liquid microextraction method, that we have termed continuous-flow microextraction (CFME), is described. In a 0.5-mL glass chamber, an organic drop (1-5 microL) is held at the outlet tip of a polyetheretherketone (PEEK) connecting tubing which is immersed in a continuously flowing sample solution and acts as the fluid delivery duct and as a solvent holder. Extraction takes place between the organic drop and the flowing sample solution that is continuously ejected out of the PEEK tubing. Concentration factors of between 260- to 1600-fold are achieved within 10 min of extraction. Aspects relevant to CFME were studied. In combination with gas chromatography-electron capture detection, CFME allows analytes to be detected at femtogram-per-milliliter levels. The performance of this technique was evaluated on the basis of the analysis of trace nitroaromatic compounds and chlorobenzenes in environmental samples.

Automation of Liquid–Liquid Extraction–Spectrophotometry Using Prolonged Pseudo-Liquid Drops and Handheld CCD for Speciation of Cr(VI) and Cr(III) in Water Samples

“…20 Besides, owing to the volume of a liquid drop being only a few microlitres, a high enrichment factor can be obtained easily by using single-drop extraction (SDE). 1,[21][22][23][24][25][26] However, the length of the optical path of a liquid drop is quite limited; thus it cannot provide sufficient sensitivity in the spectrometric determination. Therefore, to prolong the length of the optical path of a drop, a prolonged pseudo-liquid drop using a T-tube was developed in our laboratory.…”

A review of current trends and advances in modern bio-analytical methods: Chromatography and sample preparation

“…When the extraction chamber is full of sample, a drop is formed at the tip of a micro-syringe needle. In contrast with other SDME, the solvent drop makes contact with fresh and flowing sample solution [140,141]. Due to the continuous contact with the flowing fresh sample solution, the extraction efficiency and concentration factor are higher than in static extraction.…”

Determination of phthalate esters in liquor samples by vortex‐assisted surfactant‐enhanced‐emulsification liquid–liquid microextraction followed by GC–MS

“…The first methodology evolved from LPME was single-drop microextraction (SDME), which was developed by Liu [6]. Since the introduction of SDME, different analytical modes, including liquid-liquid-liquid microextraction [7], continuous-flow microextraction [8], headspace SDME [9], hollow-fiber LPME [10] and solid-drop LPME [11] have been developed for various analytical applications. Among all these analytical modes, a new type of LPME method termed as dispersive liquid-liquid microextraction (DLLME) has attracted more and more attention since its introduction by Rezaee et al in 2006 [12].…”