Solid extraction of organic compounds : a critical review - Part II

International audienceSolid Phase Extraction (SPE) is the most widely used method for the extraction, changing of solvents, clean-up, concentration and fractioning of organic compounds from clinical, biological, industrial, environmental, marine and food samples. However, most SPE procedures are still poorly developed with little consideration to the physics involved in the process and are described as a largely empirical, labour intensive and time consuming trial and error process, without much systematization.Here we attempt to throw the light on a lot of disagreements concerning the suitability of each sorbent for the extraction of a number of compounds, conditioning, washing off and elution protocols and regarding the recoveries achieved by a particular SPE protocol. This serious lack of systematization and homogenization makes difficult the efficient implementation of reliable SPE procedures.Particularly, this part is focused on the advantages and disadvantages of SPE vs Liquid-Liquid Extraction (LLE), controversies and contradictions found in literature as regards selection of sorbents, optimization of conditioning and elution protocols and recoveries by SPE. Moreover, it reveals the lack of selectivity of most of sorbents and SPE protocols and also includes the following sections: applications of SPE, fractionation by SPE, outlook and perspectives and conclusions

Solid phase extraction of organic compounds: a critical review - Part I

International audienceSolid Phase Extraction (SPE) is the most widely used method for the extraction, changing of solvents, clean-up, concentration and fractioning of organic compounds from a number of samples. This procedure is also very useful for desalting proteins and sugar samples. However, most SPE procedures are still poorly developed, with little consideration to the physics involved in the process and are described as largely empirical, labour intensive and time consuming trial and error processes, without much systematization.This critical review aims to put forward a number of contradictions, disagreements, failings and shortcomings of the SPE procedures found in literature. The different arguments here introduced, attempt to challenge the suitability of this procedure, especially when it is carried out in the traditional way (under gravity and at high flow rate).The first part of the critical review focuses on describing the state-of-the-art SPE and is physical fundamentals of SPE

Solid phase extraction – Multisyringe flow injection system for the spectrophotometric determination of selenium with 2,3-diaminonaphthalene

International audienceIn the present work, a solid phase extraction (SPE) is hyphenated with an automatic MSFIA system to improve the selenite determination based on the reaction of selenite with aromatic o-diamines (such as 2,3-diaminonaphthalene (DAN)) to form the piazselenol complex. This reaction is greatly influenced by acid concentration, temperature, the time needed for colour development, and presence of foreign ions.For these reasons a thermostatic bath, glycine, and Na2-EDTA are used as heater, buffer, and masking agent, respectively. The principle of the determination is based on the sorption of the piazselenol onto a C18 membrane disk, followed by its elution by acetonitrile. The piazselenol can then be detected by absorptiometry or fluorometry, both detection techniques being tested in our system. The best detection limit (1.7 g L−1) and RSD (3.04%) are obtained by absorptiometry at 380 nm. Environmental samples were spiked and analyzed, with recoveries close to 100%