Table 2 Overview of techniques suitable to extract PCBs
From: Analysis, occurrence and removal of polychlorinated biphenyls (PCBs) in mine water – A review
Method name | Principle | Advantages | Disadvantages | Application examples | References |
|---|---|---|---|---|---|
Liquid–liquid extraction (LLE) | Separation of compounds or metal complexes is based on relative solubilities in two different immiscible liquids | High capacity of the extractant and high selectivity of separation | Cannot be automated, uses higher volumes of solvents and samples, time consuming and laborious, formation of stable emulsions | Analysis of PCBs in river, lagoon, and runoff water samples | |
Solid-phase extraction (SPE) | Dissolved or suspended compounds in a mixture are retained on a packed cartridge according to physical and chemical properties | Fast, presents low contamination risk and can be used online | Uses higher volumes of samples, uses solvents, time consuming and laborious, costly, complex matrix causes settling in cartridges, cannot be automated | Determination of PCBs in wastewater, lake water and water samples | Aydin et al. [14], Nellier et al. [182], Westbom et al. [267], Xu et al. [276] |
Solid-phase microextraction (SPME) | Partitioning of analytes between the sample and a polymer-coated fibre | Rapid, simple, solvent free, extraction from the sample or the headspace above a sample, dissolved and total concentrations can be analysed | Costly infrastructure, fragile coating layer of fibre, laborious method development, longer analysis time per sample | Determination of PCBs in industrial harbour water, sediment pore water, water in bioconcentration studies, mine water | Böhm et al. [29], Hawthorne et al. [95], Lambropoulou et al. [133], Llompart et al. [149], Wiltschka et al. [270] |
Stir bar sorptive extraction (SBSE) | SPME principle, polymer coating on a magnetic stirring rod | Allows usage of larger sample sizes and is more robust | The technique uses a desorption step which needs an additional cooling trap and is complex to automate | Analysis of PCBs in snow samples in the Aconcagua Mountains in the Andean Range and in environmental waters | |
Passive sampling | Partitioning of analytes between the water phase and the passive sampling phase (here: a hydrophobic uptake material) | Analysis of trace concentrations, time weighted average concentrations | Laborious quantification | Analysis of PCB concentrations in water and sediments | Lohmann et al. [150], Mayer et al. [164], Smedes et al. [227] |
Disperse liquid–liquid microextraction (DLLME)* | Fine droplets of extraction solvent are dispersed in an aqueous sample. High collective area of the solvents facilitates partitioning of analytes into the extraction phase | Short extraction time, uses small volumes of solvent and water, rapid and easy to use, cost-effective, no sample carryover, requires no instrument modification, high recovery of analytes | Difficult to automate, the use of dispersive solvents decreases the partition coefficient of analytes into the extraction solvent | Determination of PCBs in water and soil samples | Hu et al. [105], Rezaei et al. [204], Temerdashev et al. [239] |
Ultrasound-assisted emulsification solvent extraction (USAEME)* | Ultrasonic radiation is applied to accelerate emulsification which favours the mass transfer of analytes from aqueous phase into organic phase thereby enhancing extraction efficiency | Viable, cost-effective, simple, rapid, less solvent and sample used | Excessive ultrasonic energy may degrade analytes and cause permanent damage to the properties of analytes | To enhance crystallisation processes in many industrial domains, such as chemical, pharmaceutical, and petrochemical industries, determination of PCBs in water samples | de Castro et al. [58], Ozcan et al. [188], Yurdakok-Dikmen et al. [282] |
Membrane-assisted solvent extraction (MASE)* | Analytes are preconcentrated using a membrane that protect the acceptor phase or solvent, where the analytes from the donor phase or sample are concentrated | Allows extraction of analytes from extremely dirty matrices. Allows automation of solvent addition, extraction, and injection steps | Solvent may dissolve unwanted pyrolysis products, matrix material and other substances which may interfere with subsequent analysis | Extraction of PCBs from estuarine water, seawater, river water and beverages | |
Vortex-assisted liquid–liquid microextraction (VALLME) | Dispersion of the solvent phase into the aqueous solution provided using vortex and miniaturisation | Fast; short extraction time, repeatable, efficient, requires small volumes of solvent and sample, high recovery | Limited number of appropriate extractants | Extraction of PCBs from different water and wastewater samples |