Solidification of floating organic droplet in dispersive liquid-liquid microextraction as a green analytical tool

• Published in: Talanta (Oxford) Vol. 170; pp. 22 - 35
• Main Authors: Mansour, Fotouh R., Danielson, Neil D.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2017
• Subjects: agitation; centrifugation; Dispersive liquid-liquid microextraction; droplets; emulsions; freezing point; halogenated hydrocarbons; liquid-phase microextraction; melting; Microextraction; mixing; solidification; Solidification of floating organic droplet; solvents; temperature; toxicity; NN; TTA; SAP; SM-DLLME; ST-DLLME; CTAB; FAAS; SFOD; SPME; ETAAS; LDS; Solidification of floating organic droplet; ICP OES; AA-DLLME; DDTP; 8-HQ; DAB; PBDEs; CAD; ECD; GAC; USA-DLLME; OVAC; BSCD; TEME; APDC; DDTC; SI-DLLME; AAS; TPMEDA; Microextraction; PAHs; Dispersive liquid-liquid microextraction; LLME; PAN; VA-DLLME; DLLME; GFAAS; SA-DLLME
• ISSN: 0039-9140; 1873-3573; 1873-3573
• DOI: 10.1016/j.talanta.2017.03.084

Dispersive liquid-liquid microextraction (DLLME) is a special type of microextraction in which a mixture of two solvents (an extracting solvent and a disperser) is injected into the sample. The extraction solvent is then dispersed as fine droplets in the cloudy sample through manual or mechanical agitation. Hence, the sample is centrifuged to break the formed emulsion and the extracting solvent is manually separated. The organic solvents commonly used in DLLME are halogenated hydrocarbons that are highly toxic. These solvents are heavier than water, so they sink to the bottom of the centrifugation tube which makes the separation step difficult. By using solvents of low density, the organic extractant floats on the sample surface. If the selected solvent such as undecanol has a freezing point in the range 10–25°C, the floating droplet can be solidified using a simple ice-bath, and then transferred out of the sample matrix; this step is known as solidification of floating organic droplet (SFOD). Coupling DLLME to SFOD combines the advantages of both approaches together. The DLLME-SFOD process is controlled by the same variables of conventional liquid-liquid extraction. The organic solvents used as extractants in DLLME-SFOD must be immiscible with water, of lower density, low volatility, high partition coefficient and low melting and freezing points. The extraction efficiency of DLLME-SFOD is affected by types and volumes of organic extractant and disperser, salt addition, pH, temperature, stirring rate and extraction time. This review discusses the principle, optimization variables, advantages and disadvantages and some selected applications of DLLME-SFOD in water, food and biomedical analysis. Extraction procedures of solidification of floating organic droplet in dispersive liquid-liquid microextraction. [Display omitted] •DLLME-SFOD is simple, with enhanced extraction kinetics and efficiency and requires small volumes of organic solvent.•The recent applications in body fluids, sludges, fruits and vegetables indicate that DLLME-SFOD is a promising technique.•Selected applications of DLLME-SFOD in determination of organic and inorganic analytes are summarized in tables.•The centrifugation step in DLLME-SFOD could be omitted by using a solvent-terminated DLLME to demulsify the mixture.•More work on the automation of the different steps of DLLME-SFOD is expected in the future.